How does drug-induced photosensitivity work?

How does drug-induced photosensitivity work?

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Some drugs (tetracyclines, for instance) can cause photosensitivity reactions-that is, some patients become extremely sensitive to the sun, developing rashes or inflammation after spending time in bright sunlight. Sources I've read describe this as an immune reaction similar to an allergy, but I've also heard that antihistamines are generally ineffective at treating such reactions.

So my question is, what are the biological processes behind this reaction, and how does it differ from a normal skin allergy that could be treated by antihistamines?

Drug induced photosensitivity (DIP) refers to the development of a cutaneous disease in response to the drug chemical in combination with light. Only the drug or light alone cannot cause the reaction and both are required to be present together. The underlying pathophysiology is important clinically to identify the type of cutaneous manifestation the drug-light combo has caused. There are majorly two types of reactions, phototoxic and photoallergic reactions.

Also, the kind of light required depends on the kind of drug and the the wavelength at which it gets photoexcited. Although UV-B is a mojor cause of sunburn, the wavelength required for DIP for most drugs falls in the UV-A part of the spectrum.

Phototoxic reaction

Phototoxic damage refers to the direct damage the photoactivated drug can cause to the tissue. Light leads to excitation of electrons and as they return, they can lead to formation of reactive oxygen species which damage the cell membranes and DNA. This tissue damage leads to activation of proinflammatory cell signal transduction pathways and leads to inflammation in the area. Clinically, it looks like an exaggerated sun burn.

Photoallergic reaction

This is similar to the same old hapten story. A drug which is otherwise non-antigenic turns antigenic after a photoreaction. Most probably, the reaction should have caused the modified drug to bind to cutaneous proteins leading to cell mediated immune reaction. This T-cell mediated inflammatory response usually has an eczematous morphology if the photoallergen is applied topically or the characteristics of a drug eruption if the photoallergen is administered systemically

It is important to differentiate the kind of reaction, a drug would cause.For example, the tetracyclines that you mention are phototoxic but not photoallergic. Photoallergic reactions have far lesser incidence than phototoxic ones.

Coming to the other part of your question, on the treatment, most important is to educate your patient for appropriate photoprotection. If severe, the drug could be withdrawn and switched to a safer one. Treatment includes topical corticosteroids to bring down the inflammation in either reactions. Oral antihistaminics are reported to have limited advantage. Why this is so,I'm afraid, I do not know. Hence your question remains partly answered.


Sun-Sensitive Drugs (Photosensitivity to Drugs)

Photosensitivity (or sun sensitivity) is inflammation of the skin induced by the combination of sunlight and certain medications or substances. This causes redness of the skin and may look similar to sunburn. Both the photosensitizing medication or chemical and light source have to be present in order for a photosensitivity reaction to occur.

Generally, these reactions can be divided into two mechanisms:

Phototoxic drugs are much more common than photoallergic drugs.

Making Sense of Sunscreen Products

Most people are understandably confused when it comes to choosing a sunscreen because of the baffling array of available choices. Common questions about sunscreens include

  • How high should the SPF be?
  • Should it block UVA or UVB?
  • Does it matter whether it is a gel, cream, or spray?
  • Should it be water-resistant or waterproof?

SPF stands for sun protection factor. The SPF numbers on a product can range from as low as 2 to as high as 60. These numbers refer to the product's ability to screen or block out the sun's burning rays. The SPF rating is calculated by comparing the amount of time needed to produce sunburnon protected skin to the amount of time needed to cause a sunburn on unprotected skin. The higher the SPF, the greater the sun protection.

What is the difference between a photoallergic and a phototoxic reaction?

Phototoxic reactions

In phototoxic reactions, the drug may become activated by exposure to sunlight and cause damage to the skin. The skin's appearance resembles sunburn, and the process is generally acute (has a fast onset). Ultraviolet A (UVA) radiation is most commonly associated with phototoxicity, but ultraviolet B (UVB) and visible light may also contribute to this reaction.

Rash from a phototoxic reaction is mainly confined to the sun-exposed area of the skin. A phototoxic reaction typically clears up once the drug is discontinued and has been cleared from the body, even after re-exposure to light.

Photoallergic reactions

In photoallergic reactions, the ultraviolet exposure changes the structure of the drug so that is seen by the body's immune system as an invader (antigen). The immune system initiates an allergic response and cause inflammation of the skin in the sun-exposed areas. These usually resemble eczema and are generally chronic (long-lasting). Many drugs in this family are topical drugs.

This type of photosensitivity may recur after sun exposure even after the drug has cleared from the system and can sometimes spread to areas of the skin unexposed to the sun.


Photoallergic and phototoxic reaction pictures

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What are the signs and symptoms of sun sensitivity (photosensitivity)?

Symptoms of phototoxic reaction

Individuals with phototoxic reactions may initially complain of a burning and stinging sensation. Redness typically occurs within 24 hours of the exposure to sun in the exposed areas of the body such as the forehead, nose, hands, arms, and lips. In severe cases, sun protected areas of skin may be also be involved.

The range of skin damage may vary from mild redness to swelling to blister formation in more severe cases. The rash from this photosensitivity reaction usually resolves with peeling and sloughing of (shedding) skin in the affected area within several days.

Symptoms of photoallergic reactions

Individuals with photoallergic reactions may initially complain of itching. This is then followed by redness and possibly swelling and eruption in the involved area. Because this is considered type of an allergic reaction, there may be no symptoms for many days when the drug is taken for the first time. Subsequent exposure to the drug and the sun may cause a more rapid response in 1-2 days.

Hyperpigmentation after reaction

Hyperpigmentation (darkening) of the affected area of the skin may develop after the resolution of a phototoxicity reaction, but it is rare in a photoallergic reaction. In phototoxic reactions, high doses of the drug and long exposures to light may be required to cause the reaction.

Can tanning beds cause a sun sensitive reaction?

Yes. Ultraviolet (UV) light is radiation energy in the form of invisible light waves. UV light is emitted by the sun and by tanning lamps. The sun discharges three types of ultraviolet radiation,

Only UVA and UVB rays reach earth. (UVC does not penetrate the earth's upper atmosphere.) Tanning lamps also produce UVA and/or UVB. These artificial rays affect the skin in the same way as do UVA and UVB from the sun.


List of examples of medications that cause phototoxicitcy

Common phototoxic drugs include:


  • quinolonesfor, example, ciprofloxacin (Cipro, Cipro XR, ProQuin XR), and levofloxacin (Levaquin)
  • tetracyclines, for example, tetracycline (Achromycin), doxycycline (Vibramycin, Oracea, Adoxa, Atridox and others (sulfa drugs), for example, sulfamethoxazole and trimethoprim cotrimoxazole (Bactrim, Septra), and sulfamethoxazole (Gantanol)


Malaria medications

Cancer chemotherapy drugs

Other cancer drugs

  • Epidermal growth factor receptor inhibitors, for example, cetuximab (Erbitux), panitumumab (Vectibix), erlotinib (Tarceva), gefitinib (Iressa), lapatinib (Tykerb), vandetanib (Caprelsa)
  • BRAF inhibitors, for example, vemurafenib (Zelboraf), sorafenib (Nexavar)

Cardiac drugs

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What are other examples of drugs that cause phototoxicity?

BRAF inhibitors

HMG-CoA reductase inhibitors


Drugs that treat diabetes


Skin medications

    for skin cancer, for example, ALA or 5-aminolevulinic acid (Levulan), Methyl-5-aminolevulinic acid, verteporfin (Visudyne), and porfimer sodium (Photofrin). medications (Accutane) (Soriatane)

Psychiatric drugs


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List of examples of drugs that cause photoallergic reactions

Examples of some of the common photoallergic drugs include:


  • Para-aminobenzoic acid (PABA) - PABA has been phased out of sunscreen preparations because of the high rate of allergic reactions to this chemical.
  • oxybenzone
  • cyclohexanol
  • Benzophenones
  • Salicylates
  • cinnamate



Cancer chemotherapy drugs


These are only some of the common sun-sensitizing drugs.

Is anyone taking these drugs at risk for developing sunburn?

Not everyone taking any of these drugs will develop photosensitivity reactions. Certain individuals have more susceptibility to these medications than others.


What foods and plants cause sun sensitivity (photosensitivity) reactions?

Some vegetables and plants may cause sun sensitivity if they come into contact with the skin. Mango peel, lime juice, parsnips, or celery, for example, may cause temporary discoloration (darkening) of the skin contact area when in the sun. Common phototoxic fruits and vegetables include:

  • Lime
  • Celery
  • Carrots
  • Figs
  • Parsley
  • Parsnips
  • Mango peel

Pictures of food and plant sun-sensitivity (photosensitivity) reactions

What diseases or other health problems cause photosensitivity?

Some medical conditions are known to cause sensitivity to sun exposure.

Systemic lupus erythematosus (SLE) often causes a rash on the face which can be very sensitive to sunlight. This rash is typically seen on the nose and cheeks, called a malar rash, and is considered one of the hallmarks of lupus.

Porphyria is another medical condition that may cause photosensitivity reactions. This is a hereditary condition with skin manifestation (cutaneous porphyria) causing rashes and blisters in reaction to exposure to sunlight.

Vitiligo is a relatively common disorder that causes patches of white de-pigmented skin. These patches lack melanin and are extremely sensitive to UV rays.

Xeroderma pigmentosum is a disorder that appears to result from an inherited hypersensitivity to the cancer-causing (carcinogenic) effects of ultraviolet light. Sunlight causes DNA damage that is normally repaired. Individuals with xeroderma pigmentosum have defective inability to repair the DNA after UV damage. Affected individuals are hundreds of times more vulnerable to developing skin cancer than other people. Their extreme skin photosensitivity predisposes them to pronounced skin damage and scarring and also to the early onset of skin cancer (basal cell and squamous cell carcinomas and malignant melanoma).

Individuals with classic oculocutaneous albinism lack melanin in their skin and eyes - the term oculocutaneous" comes from "oculo" for eyes, and "cutaneous" for skin. Without the protection of this pigment, their white skin and pink eyes are both highly sensitive to UV and susceptible to the rays' damage.

How is sun sensitivity (photosensitivity) diagnosed?

The diagnosis of sun sensitivity is mainly made by a thorough history, examination, and review of medications and duration of exposure to sun. It is important to ask when the medication was started and for how long the symptoms persisted.

There are no diagnostic tests available, although a photo-patch test may be performed. This test is typically performed by a dermatologist (a doctor who specializes in diseases of the skin) by shining light onto different areas of the skin to see how long it will take for the light to cause redness. This test may be useful in evaluating photosensitivity to topical medications causing a photoallergic response. In cases of phototoxicity reactions, this test is generally not useful.

What is the treatment for a photosensitizing drug reaction?

Recognizing and discontinuing the photosensitizing drug is the most important step in treatment. In general, the usual sunburn prevention methods such as the use of sunscreens and avoidance of prolonged exposure to sun are important steps to take. Keeping the area of skin eruption moist and applying wet dressings may help relieve the symptoms. The reaction may last up to a few weeks.

Topical steroid creams may be helpful in treating the redness, and antihistamines are generally helpful in minimizing the itching. In severe cases, a short course (10-14 days) of oral steroids, under the direction of a doctor, may be used.

Are there any medical applications of sun sensitivity (photosensitivity)?

Photodynamic therapy utilizes the concept of sun or light sensitivity to treat some skin conditions including skin pre-cancers (actinic keratosis), skin cancers, and acne. Briefly, this treatment takes advantage of activating a photosensitizing drug (such as 5-aminolevulinic acid) by shining light directly onto it for a short time. The drug is first applied to the area of the skin where the cancer or pre-cancer is found. With light-induced activation of the drug, the abnormal cells (cancer or pre-cancer) are destroyed preferentially.

Your daughter may be having a "drug-induced photosensitivity reaction" to the Elavil (amitriptyline) she is taking. Several studies have noted that amitriptyline is associated with these types of reactions.

Although there are several proposed mechanisms behind this occurrence, it is thought that reactions are induced when the drug absorbs UVA light, causing skin damage and a visibly affected area. These types of reactions generally have a rapid onset (after sun exposure) and often look like a sunburn.

If the reaction that your daughter is more serious and affects area of the skin that are not exposed to the sun, it may be what is known as a "photoallergic" reaction, which is uncommon, but again, has been associated with amitriptyline use. Unlike photosensitivity reactions, which only affect areas of the skin exposed to the sun, photoallergy reactions manifest all over the body, and generally look like a eczematous rash, which are red, scaly and itchy.

It is important to speak with the doctor regarding the sun reactions your daughter is having from taking amitriptyline. If it is a photoallergy reaction, it is generally a good idea to consider alternative medications. If it is a photosensitivity reaction, prevention may be easier to undertake.

Preventing Elavil Photosensitivity Reactions

The best prophylaxis to amitriptyline associated photosensitivity reactions is to simply avoid sun exposure or cover exposed skin with clothes, although this is easier said than done. The next step is to use a broad spectrum sunscreen, that protect against both UVA and UVB rays. Remember that you should wait about 30 minutes after applying sunscreen to go into the sun.

Lastly, sometimes individuals can reduce the severity of photosensitivity by taking the responsible medication, amitriptyline in this case, at night, as opposed to the morning. This results in lower drug levels in the body during the times of day where sun exposure is high.

In terms of treatment, general sunburn care applies. You can use a cool compress as often as needed. Sometimes, topical products like Sarna can help with the itching. If the reaction is more severe, topical or systemic steroids may be recommended by the doctor.

Be sure to discuss the problems with the medication with the doctor to find the most appropriate way to manage this issue. It could involve more preventative measures, a dose decrease or a change of medication.

How does drug-induced photosensitivity work? - Biology

Photosensitivity refers to various symptoms, diseases, and photodermatoses caused or exacerbated by exposure to sunlight. Photosensitive conditions are classified into five categories, which include primary or autoimmune photodermatosis, exogenous or drug/chemical-induced photodermatosis, photo-exacerbated or photo-aggravated dermatoses, metabolic photodermatosis, and genetic photodermatosis. This activity illustrates the evaluation, treatment, and potential complications associated with photosensitive conditions and the importance of an interprofessional team approach to the care of affected patients.

  • Identify the classifications of photosensitivity and the diseases associated with each.
  • Review typical presenting features of photosensitive conditions.
  • Summarize the special precautions that photosensitive patients should take.
  • Explain the importance of enhancing coordination among the interprofessional team in managing those with this condition.


Photosensitivity refers to various symptoms, diseases, and conditions (photodermatoses) caused or exacerbated by exposure to sunlight[1]. It is classified into five categories: primary photodermatosis, exogenous photodermatosis, photo-exacerbated dermatoses, metabolic photodermatosis, and genetic photodermatosis.

Primary or autoimmune photodermatoses

  • Polymorphic light eruption[2]
  • Juvenile spring eruption
  • Actinic folliculitis
  • Actinic prurigo[3]
  • Solar urticaria[4]
  • Chronic actinic/photosensitivity dermatitis[5]
  • Hydroa vacciniforme (associated with Epstein-Barr virus)[6]

Exogenous or drug/chemical-induced photodermatoses[7][8]

  • Drug-induced photosensitivity: common photosensitizing drugs are thiazides, tetracyclines, non-steroidal anti-inflammatory drugs (NSAIDs), phenothiazines, voriconazole, quinine, vemurafenib, and many others[7]
  • Photocontact dermatitis: due to phototoxic chemicals such as psoralens in plants, vegetables, fruit fragrances in cosmetics sunscreen chemicals dyes and disinfectants[9]
  • Pseudoporphyria: induced by drugs and/or renal insufficiency[10]

Photo-exacerbated or photo-aggravated dermatoses

  • Cutaneous lupus erythematosus (acute, subacute and chronic variants)[11]
  • Dermatomyositis[12]
  • Sjogren syndrome
  • Darier disease[13]
  • Rosacea[14]
  • Melasma[15]
  • Pemphigus vulgaris
  • Pemphigus foliaceus[16]
  • Atopic dermatitis[17]
  • Seborrhoeic dermatitis[18]
  • Psoriasis[19]
  • Lichen planus (actinicus)[20]
  • Erythema multiforme[21]
  • Mycosis fungoides[22]

Metabolic photodermatoses (rare)

  • Porphyria cutanea tarda[23]
  • Erythropoietic protoporphyria
  • Variegate porphyria[24]
  • Erythropoietic porphyria (Gunther disease)[25]

Genetic photodermatoses (very rare disorders due to genomic instability)

  • Xeroderma pigmentosum[26]
  • Cockayne syndrome[27]
  • Trichothiodystrophy[28]
  • Bloom syndrome[29]
  • Rothmund Thomson syndrome[30]


The etiology of a photodermatosis depends on its classification (see individual topic articles). Some are due to autoimmune reactions, drugs, connective tissue disease, and abnormal inherited biochemical pathways.


Photosensitivity may be observed in both males and females at all ages and in all ethnic groups. Different types of photosensitivity may be prevalent at different times of life. Genetic and environmental factors intervene in the occurrence of photosensitivity.


Photosensitivity is caused by an abnormal reaction to a component of the electromagnetic spectrum of sunlight and a chromophore (reactive compound) within the skin. Patients can be sensitive to one kind of sunlight, for example only to ultraviolet radiation, ultraviolet A or B (UVA, UVB), or visible light, or to a wider range of radiation. The most common photosensitivity is to UVA. Mainly, exposure to visible light triggers porphyria.


Each category and sub-category of photosensitivity has a unique reaction pattern seen on pathology. See the individual chapter for the unique histopathologic characteristics of each entity.

History and Physical

The clinical features depend on the specific photodermatosis.

  • Photodermatoses affect areas exposed to sunlight, usually the face, neck, hands, and do not affect areas not exposed to the light (covered at least by underwear), or are less severe in covered areas.
  • Sometimes they spare areas that habitually are exposed to the light, for example, the face of a polymorphic light eruption.
  • Sometimes they only affect certain parts of the body, for instance, juvenile spring eruption is confined to the tops of the ears.
  • Photodermatoses may also occur following indoor exposure to artificial sources of UVR like fluorescent lamps or visible radiation.
  • Genomic instability due to DNA repair deficiency disease causes pigmentary changes and high risk (1000 times normal) of skin tumors including basal cell carcinoma, squamous cell carcinoma, and melanoma.
  • Children with the photosensitive genodermatoses have characteristic cutaneous features and abnormalities of other organs.

Clues to photosensitivity include: 

  • Summer exacerbation although, note that many photodermatoses are present year round
  • Sharp cut-off between affected area and skin covered by clothing or jewellery (e.g., watch strap, ring)
  • Sparing of folds of upper eyelids
  • Sparing of deep furrows on face and neck
  • Sparing of skin covered by hair
  • Sparing of skin shadowed by the ears, under the nose and the chin
  • Sparing of the web spaces between the fingers.


Medical practitioners diagnose photosensitivity by a history of a skin problem arising from exposure to sunlight. They determine the specific type by taking a careful history, examining the skin and performing specific tests. Photosensitivity is sometimes confirmed by photosets, which only is available in specialized centers.

  • Minimal erythema dose (MED) testing (broadband or monochromators) to determine threshold dose
  • Provocation photoset procedure using repeated exposures to UVA and/or UVB over four consecutive days in an attempt to reproduce the dermatosis
  • Photopatch tests in association with standard patch tests to determine photoallergy

Investigations may include:

  • Full blood count
  • Connective tissue antibodies including antinuclear antibodies (ANA), extractable nuclear antigens (ENA) if suspicious of lupus erythematosus
  • Porphyrins in blood, urine, and feces
  • Liver function and iron tests in patients suspected of porphyria
  • Skin biopsy for histopathology and direct immune fluorescence in primary and photo-exacerbated dermatoses
  • In cases suspicious of xeroderma pigmentosum, measurement of post-UV cell survival and DNA repair capacity in fibroblast assays
  • Tiger hair appearance on polarised microscopy of brittle hair (dark and light areas) should lead to chromatography to determine amino acid content, which shows reduced cysteine in trichothiodystrophy
  • Gene sequencing may confirm Bloom syndrome or Rothmund Thomson syndrome.

Treatment / Management

Management of photosensitivity involves sun protection and treatment of the underlying disorder. Mainly, photosensitivity reactions are prevented by careful protection from sun exposure and avoidance of exposure to artificial sources of UVR. Use of websites and smartphone apps that indicate local ultraviolet levels are helpful to understand when protection is most essential. There is more ultraviolet radiation in the tropics compared to temperate areas, in the Southern hemisphere compared to the Northern, during summer compared to winter, at high altitude compared to sea level, and in the middle of the day compared to the extremes of the day.

  • Avoiding exposure to direct sunlight
  • Staying indoors and away from windows, and seeking shade when outdoors
  • Dressing up in covering clothing and wearing a wide-brimmed hat when outdoors. Some clothing is labeled with ultraviolet protection factor (UPF). Best protection from clothing is obtained from thick, tightly woven, dry and dark colored polyester, denim or wool
  • Broad-spectrum sunscreen SPF 50 or higher, covering all exposed skin. Sunscreen should protect from UVB and UVA and be water resistant. It should be applied generously and reapplied every two hours while outdoors
  • Tanning products containing dihydroxyacetone provide modest photoprotection against UVA and to a lesser extent against UVB.

SPF is sun protection factor, defined as the dose of solar radiation needed to induce just perceptible erythema (minimal erythema dose, MED) on skin treated with 2 mg/cm sunscreen divided by the MED on untreated skin. SPF primarily describes protection from UVB, as it reflects protection from the erythema action spectrum.

The primary photodermatosis polymorphic light eruption may be paradoxically effectively treated by graduated, and cautious, exposure to ultraviolet radiation.[32]

Differential Diagnosis

The first step in considering a diagnosis within the broad scope of photosensitivity is to consider each category of photosensitivity and the specific entities within the given category whether it is primary photosensitivity such as polymourphous light eruption, autoimmune photosensitivity such as lupus erythematosus, photo-exacerbated or aggravated such as dermatomyositis, genetic such as xeroderma pigmentosum, or metabolic such as porphyria cutanea tarda. Then using the history and physical exam, narrow down the differential. For example, a polymourphous light eruption(PMLE) may be distinguised from lupus erythematosus by the history, presentation, and clinical appearance of these lesions. For photoexacerbated diseases such as dermatomyositis, other clinical findings such as capillary abnormalities around the nail folds or gottron papules over the bony prominences usually help with distinction from other entities such as drug enduced photosensitivity. Once the general category has been suspected, a differential can be developed within that category and helps with the diagnosis. For the differential diagnosis of each entity, please see the specific chapter of that entity.


The prognosis of each entity is unique, please see the individual chapters for each condition.


The complications of each entity is unique, please see the individual chapters for each condition.

Deterrence and Patient Education

In general, treatment of photosensitivity regardless of the entity is going to center around managing symptoms and pursuing photoprotection. 

Pearls and Other Issues

Patients with photodermatoses also may need to: 

  • Take vitamin D supplements and oral antioxidants
  • Wear a clear plastic mask to protect the face 
  • Choose gray-tinted laminated glass for automobile
  • Apply photoprotective UV films to windows at home, school work, and vehicles
  • Have regular skin checks to locate and treat skin cancers early.

Enhancing Healthcare Team Outcomes

The healthcare team, including nurses, pharmacists, and clinicians must work together to educate patients with photodermatoses as they need to be reminded to take vitamin D supplements and oral antioxidants, wear a clear plastic mask to protect the face, choose gray-tinted laminated glass for their automobile, and apply photoprotective UV films to windows at home, school work, and vehicles. The team should remind patients they need to have regular skin checks to locate and treat skin cancers early. [Level V]

Diseases Related to Abnormal Photosensitivity Responses of the Skin

Actinic folliculitis is a dermatosis that results in patches of small (1 to 3 mm) raised bumps on the skin that can be pink or pale in color. These rashes are often found on the face, neck or trunk and appear four to six hours following exposure to sunlight. Most regularly used acne treatments are not very effective in minimizing this outbreak, but oral isotretinoin can be effective.
This disorder is very rare and is related to other acne disorders such as acne aestivalis and actinic superficial folliculitis.

Hawk, John L., and Paul G. Norris. “Abnormal Responses to Ultraviolet Radiation: Idiopathic.” Dermatology in
General Medicine. Fourth ed. 2 vols. New York: McGraw-Hill, Inc., 1993.

2. Actinic Prurigo

Actinic prurigo is a disorder that produces rashes consisting of tiny itchy red dots (papules). The eruption produced tends to resemble eczema (atopic dermatitis) but is usually more severe. These lesions are usually most intense on skin that has been exposed to UV radiation such as the face, neck, arms, and upper chest. A more mild reaction can sometimes be observed on those parts of the body that are hidden from the sun. In 60-70% of patients a rash develops on the lips and conjunctiva of the eyes is found in 45%.

Actinic prurigo can last all year long with rashes sometimes taking weeks or months before they subside. Occasionally lesions will appear in the winter, although outbreaks tend to be most intense during months when the skin is most exposed to ultraviolet radiation. In certain patients the rash will be the most severe in the months prior and following peak UV exposure due to the skin’s ability to become more tolerant as exposure to sunlight approaches its peak. As the lesions remain on the skin for long periods of time, sunshine tends to aggravate pre-existing rashes rather than produce new ones.

People with darker skin most often develop this disease, especially the Native Americans of Mexico, Central America, and Southern America. Those suffering from the disorder will usually develop their first rashes by ten years old. Those that experience later onsets of the disorder are twice as likely to be female.

Damage done to exposed skin does not seem to be minimized when using sunscreens, including those that have high SPFs. Because normal sun protectors are not very effective in reducing the likelihood of an outbreak, the best way to prevent rashes is to avoid exposure to sunlight as much as possible. Thalidomide has been found to be effective in treating the disorder when prescribed at a low-dosage. This drug, however, is a teratogen, meaning it has the potential to harm a developing fetus, and should therefore be avoided during pregnancy.

Hawk, John L., and Paul G. Norris. “Abnormal Responses to Ultraviolet Radiation: Idiopathic.” Dermatology in
General Medicine. Fourth ed. 2 vols. New York: McGraw-Hill, Inc., 1993.

3. Bloom Syndrome

Bloom syndrome (also known as telangiectatic erythema) is a rare inherited disorder that can result in the appearance of small red capillaries (telangiectases) on affected areas of skin, delayed growth at birth, small stature, immunodeficiency, infertility, mental retardation and an increased likelihood of developing cancer.

This genetic disorder follows an autosomal recessive pattern, meaning that both parents must donate a copy of the gene (in which case each parent is a carrier of the mutated gene) to their child, who has a 1 in 4 chance of being born with Bloom syndrome. The disease is believed to be the result of a mutation in the BLM gene, causing chromosomes to break and rearrange more often.

Bloom syndrome is a disorder that is most common in East European Ashkenazi Jews, but has also been found in people of Japanese descent. Men are slightly more likely to have the syndrome than women.

The most common first signal of Bloom syndrome is a small size at birth and a subsequent slow growth rate. As a person with Bloom syndrome ages, he/she will often develop certain symptoms of the disorder in addition to those already mentioned. These include a high-pitched voice, narrow face, prominent ears, small lower jaw, an enlarged nose, large hands and feet and disproportionate arms. Additionally, ailments including diabetes, pneumonia, and various infections are more common in people with this disorder.

An increased sensitivity to sun is very common in cases of Bloom syndrome. Rashes that form as a reaction to UV light are usually butterfly-shaped areas found on facial skin, hands, and arms. Dilated blood vessels are also very common. Cheilitis, or the drying and crusting of the lips, is common following irritation by the sun. Fortunately photosensitivity and erythema (inflammation and redness of skin due to irritation by the sun) decrease with age.

The probability of growing of a malignant tumor is 150% to 300% greater in these patients than it is in the normal population. In fact, 20% of people with Bloom syndrome develop a malignant tumor at some point, often at a much younger age than the average person would. Diagnosis of such a tumor is made at an average of 25 years of age. This causes the average life span to be much lower in people with Bloom syndrome, often ending between 20 to 30 years due to the spread of malignant tumors. At age 22, leukemia is likely to develop and at 35 it is common for solid tumors to grow.

Because Bloom syndrome is a genetic disorder no treatment exists for it. As mentioned, the risk of cancer is greatly increased in those suffering from Bloom Syndrome, so monitoring the skin for growths and careful protection against sun irritation is crucial. Defense against UV rays includes minimizing exposure to sunlight, applying of a high SPF sunscreen, and wearing clothing that covers the skin from the sun’s rays.

4. Chronic Actinic Dermatitis

Chronic actinic dermatitis (CAD) is a photosensitivity disorder in which outbreaks of eczematous rashes develop most often on exposed skin. Patients suffering from the disorder often suffer form papules, or inflamed bumps, and plaques, which are scaly, raised patches of skin. These rashes often itch and are appear red in color. Nearly 90% of those suffering from CAD are males, and of these most are elderly.

Chronic actinic dermatitis refers to a number of related disorders, including persistent light reactivity, actinic reticuloid, photosensitive eczema, and photosensitivity dermatitis. The progression from one of these disorders to CAD is characterized by transition from a photoallergic contact dermatitis to a persistent photosensitivity.

It has been observed that, although the disorder can last all year long, its outbreaks become most severe during the summer months when the body is exposed to the greatest amount of UV radiation. The rashes are usually found on the backs of hands, scalps, face, and upper chest. In more extreme cases patients will have intense eruptions of papules and plaques on exposed areas of skin adjacent to other areas that are exposed yet remain healthy.
Treatment of CAD can take an extensive amount of work and involves strict avoidance of UV Radiation. In certain extreme cases patients are admitted to hospital dark rooms in order to completely avoid sunlight. If a contact dermatitis exists then this allergen must also be completely removed.

A number of medications provide a minimization of this hypersensitivity to sunlight. Azathioprine aids in the remission of the disorder after a few months. While this sometimes cures the disease, this treatment does not always last. In such cases annual treatments prior to summer can be helpful. High dose systemic or topical coricosteroids can be an effective addition to phototherapy, but the exposure to even minute amounts of UV Radiation can often irritate the skin. Cyclosporine, emollients, and topical tacrolimus are also effective treatments for this disorder.

Hawk, John L., and Paul G. Norris. “Abnormal Responses to Ultraviolet Radiation: Idiopathic.” Dermatology in
General Medicine. Fourth ed. 2 vols. New York: McGraw-Hill, Inc., 1993.

5. Darier’s Disease

Darier’s disease is a rare chronic disorder also known as keratosis follicularis. It is hypothesized that a genetic defect forces calcium to remain outside of cells rather than entering them. This mineral, however, is required to properly construct desmosomes or ‘cell connectors,’ resulting in skin cells (keratinocytes) that do not stick together properly.

The disease follows an autosomal dominant genetic pattern, meaning that only one copy of the gene is needed to cause the disease. This also means that only one parent needs to have the disease in order to pass it on to his or her offspring. If a copy of the gene is acquired by a child, however, he or she will not necessarily develop any symptoms of the disease. If a parent does have the disease, a 50% chance exists that the offspring will inherit a copy of the gene, too.

Symptoms of Darier’s disease include severe skin lesions whose severity fluctuates over time. These rashes tend to be coarse, greasy, scaly papules that are skin colored, yellow, or brown. The lesions often cover seborrheic areas of the face including the forehead, scalp, eyebrows, ears, nostrils, sides of nose, and beard area, as well as the neck and central chest and back. Skin that is covered by natural flaps occasionally develops wart like growths that have a strong odor.

Less common rashes include flat freckle-like lesions or large raised bumps that appear to be warts. Smaller warts or bleeding areas beneath the skin can also develop on soles of feet or palms. It is also common for straight red or white lines to run from the tip of the nail to the opposite end of it. Mucous membranes also tend to form papules or have a white border in those with the disorder.

Most people that show signs of Darier’s disease will develop symptoms before age 30. In many mild cases these rashes and other indicators of the disorder will rarely appear unless instigated. Often UV radiation can cause outbreaks, so it is important that those with Darier’s disease avoid direct sunlight, wear protective clothing that covers the legs and arms, and apply sunscreen on exposed skin. This is of even greater importance to those with severe cases of the disorder. Bacterial infections or Herpes virus infections are other common sources of outbreaks, so taking any necessary antibiotics can play an important role in preventing outbreaks.

Treatment of Darier’s disease is usually only necessary in severe cases. Minimization of lesions can be done through a process known as dermabrasion in which the skin is sanded down. Topical retinoids are also effective in treating rashes. In addition, oral retinoids such as acitretin, isotretinoin, and ciclosporin are useful in treating more severe cases.

6. Dermatomyositis

Dermatomyositis (DM) is a rare muscle disease that belongs to a group known as ‘inflammatory myopathies.’ In addition to weakening muscles patients tend to develop skin rashes that can itch or burn.

Patients with DM develop a number of lesions throughout the body. These include red or bluish-purple patches on the cheeks, nose, chest, elbows and other sun-exposed areas. Heliotrope (purple eyelids), purple coloring of parts of the body where bones protrude, such as the knuckles (called Gottron’s papules), ragged cuticles, amplified coloring of blood vessels on nail folds, loss of hair and a scaly scalp are all symptoms that are likely to develop before or at the same time as muscle weakness.

The most commonly affected muscles are those closest to the trunk of the body, which become tender and can ache while performing everyday activities. A common complication found in 40% of children is calcinosis, in which firm skin colored or yellow knots form over boney protrusions and can be easily infected.

Most of those with DM do survive but can become weak and disabled. If muscles become weak enough or malignancies develop, however, a chance of death does exist. Those with DM that are older than 60 have a heightened likelihood of growing tumors, making it crucial for patients to have any growths checked by a dermatologist.

In the United States approximately 5.5 people in every one million develop DM, with numbers increasing over past years. Women appear to be twice as likely to acquire DM as men are, but no trends in terms of race exist. While DM can occur at all ages, it peaks at age 50 in adults and between 5 and 10 years old in children.

In treating dermatomyositis, the foremost goal is to maintain weakening muscles. The most commonly prescribed medications are oral corticosteroids including prednisone, as well as diltiazem and colchicine for preventing calcinosis. Rest is also important for those with excessive inflammation of the muscles, but physical therapy is highly advisable for less severe cases. Although the majority of patients do require lifelong treatment, approximately 20% of patients have completely resolved symptoms.

Hydroxychloroquine is often prescribed as it reduces the outbreak produced by photosensitivity. Proper sun protection habits are also essential in minimizing the spread of rashes. These behaviors include avoiding sun exposure when possible and applying high SPF sunscreens to all exposed areas. Wearing protective clothing can also be very helpful in reducing the likelihood of an outbreak.

7. Disseminated Superficial Actinic Porokeratosis (DSAP)

This disorder is characterized by the appearance of dry lesions by age 30 or 40 that increase in number as the patient ages. These lesions are often induced by exposure to sun and are associated with immunosuppression, which has led researchers to believe that UV Radiation might play a role in hindering the immune system.

Lesions begin as conical pointed papules (bumps) that are 1-3 mm in size and expand into red-brown 10mm raised circular lesions that are incapable of sweating. Often the rim of the lesion is dark brown with a pale bordering circle. Affected areas are usually the lower legs (especially in females) and arms, but rashes rarely form on the hands, face, or scalp.
DASP is a hereditary disease that follows an autosomal dominant pattern, meaning that children of those with the disorder have a 50% chance of inheriting the gene for it. Fair-skinned people, particularly Europeans, are most likely to suffer from DASP.

Treatment of the disorder is difficult as UVA and UVB photochemotherapy often induces more lesions rather than desensitizing the skin with the intention of inhibiting future outbreaks. It is important that patients with DASP take special precautions to protect their skin by using high SPF sunscreen and cover their arms and legs when possible.

Hawk, John L., and Paul G. Norris. “Abnormal Responses to Ultraviolet Radiation: Idiopathic.” Dermatology in General Medicine. Fourth ed. 2 vols. New York: McGraw-Hill, Inc., 1993.

8. Hydroa Vacciniforme

A very uncommon disorder, hydroa vacciniforme (HV) is the result of an intensified photosensitivity. The rash produced by HV tends to form raised bumps of skin, or papules, which eventually become blisters. From these lesions comes the first term, ‘hydroa,’ in the name of the disease. Additionally, these bumps often have indented centers. After a number of weeks the papules will shed away but can leave permanent pocked scars in their place, which are represented by the term ‘vacciniforme.’ Patients suffering from hydroa vacciniforme might also experience inflamed eyelids, loosened finger and toe nails, a fever, malaise, or headaches. This dermatitis often occurs within 24 hours of exposure to sunlight.

HV affects children at a young age, but tends to subside in intensity upon reaching adolescence. Females are more likely to develop this disease, but men that do develop HV tend to produce rashes until they reach an older age.

Those that have Epstein-Barr viral infection (EBV), a disease which can cause infectious mononucleosis, occasionally develop HV. Patients with EBV tend to have more severe outbreaks in unexposed areas than a person without EBV would develop.

To minimize the severity of HV, it is recommended that patients practice extra careful sun protection behaviors such as applying high SPF sunscreens on exposed areas and avoiding sun exposure whenever possible. It can also help to wear protective clothing, especially those materials that have been scientifically tested to minimize the penetration of UV radiation. Hydroxychloroquine and beta-carotene can also be helpful in preventing outbreaks.

Hawk, John L., and Paul G. Norris. “Abnormal Responses to Ultraviolet Radiation: Idiopathic.” Dermatology in General Medicine. Fourth ed. 2 vols. New York: McGraw-Hill, Inc., 1993.

9. Lichen Planus Actinicus

Lichen Planus Actinicus is a rare disorder in which lesions form following exposure to sunlight. These patches can take on a number of different forms, with the most common being an intensely colored ring or tightly grouped pinhead papules (small raised bumps of skin) that are skin colored. Such lesions are found on the face, neck, and back of hands and usually itch.

Most often those that suffer from Lichen Planus Actinicus have dark skin and are from the Middle East, but people of all races and nationalities have developed the disease. The lesions tend to be more common during months when exposure to the sun is greatest.

The causes of this disease are not well understood, but it is hypothesized that the disorder is the result of Hepatitis C or an irregular reaction to a drug. This interaction causes the immune system to attack patches of skin which it believes to be foreign. After 18 months the disorder usually subsides. Once the lesions disappear, dark gray areas of skin often remain for a number of months.

Hawk, John L., and Paul G. Norris. “Abnormal Responses to Ultraviolet Radiation: Idiopathic.” Dermatology in General Medicine. Fourth ed. 2 vols. New York: McGraw-Hill, Inc., 1993.

10. Lupus Erythematosus

Lupus erythematosus (LE) is a group of rare skin diseases that are found mostly in females aged 20 – 50. Disorders that fall into this category include discoid LE, subacute LE, neonatal LE, cutaneous lupus mucinosis, chilblain lupus, drug-induced lupus and systemic LE.

Discoid lupus erythematosus is the most common form of LE. Those with this disorder tend to develop red scaly patches on the face, neck and scalp, chest and backs of hands that leave white scars upon fading of the rash itself. Bald spots, warts and patches of thickened skin are all common symptoms of the disorder. It is also important to carefully observe any rashes on the lips that may scar, as this can lead to squamous cell carcinoma.

The discoid form of LE can occasionally (about 10% of the time) transform into the more severe systemic LE, which has the potential to affect nearly any organ in the body. This transformation cannot be prevented or predicted, even if discoid LE is treated. Systemic LE often appears as a red rash that takes a ‘butterfly’ pattern across the face. In addition, it is common for the skin to become photosensitive and prone to developing oral ulcers and hives. Hair may also thin quickly as a result of LE.

Patients with subacute LE may form dry rashes on the back and chest following exposure to the sun. These lesions take many forms including rings, scaly bumps, purple spots and lumps. Pregnant women with this disease must notify their doctor as it can be passed to their child in the form of neonatal LE. This causes the baby to develop a ring-like rash which fades after a few months, but can lead to congenital heart blockage in the infant if left untreated.

Lupus profundus, also known as lupus pannicultius, destroys the layer of fat beneath the skin, leaving a permanent depression where the fat had been. This most often occurs in the face and can produce inflamed lumps before destroying the fat cells.

Chilblain lupus is very common in people who smoke or live in cool climates. This disorder causes circulatory problems and Raynaud phenomenon, in which fingers lose color when cold and then slowly turn blue followed by red when heating up. Blood vessels often dilate at the tips of the fingers.

One rare form of LE is cutaneous lupus mucinosis, also known as LE tumidus or papular/nodular mucinosis of Gold. The lesions that develop are most commonly small bumps, large bumps, or scaly patches that can be found on the cheeks, back, upper arms or upper chest. The name of the disorder is derived from the mucin deposits found in biopsied skin.

Most outbreaks of LE are the result of an irritant that can often be avoided, limiting the formation of new lesions. Medications including minocycline, hydralazine, carbamazepine, lithium, sulphonamides and phenytoin can induce LE and should be avoided when possible. Oral and topical steroids, corticosteroids, calcineurin inhibitors, antimalarial tablets, and laser surgery can all help to minimize scarring and reduce the size of lesions. In addition, proper sun protection is extremely important for those with lupus. Defensive behaviors against UV include avoiding direct sunlight when possible, wearing protective clothing, and applying a high SPF sunscreen.

11. Pellagra

Pellagra is a disease caused by a deficiency of niacin, also known as nicotinic acid, or the amino acid tryptophan, its precursor. This disease commonly causes diarrhea, dementia, and dermatitis, and can eventually cause death if left untreated.

This disease is most common in people who consume excessive amounts of maize, which lacks tryptophan. Thus, pellagra has been endemic in South America and Mexico, where corn is a staple food. An excessive consumption of millet also causes the disease as it contains abundant leucine, which interferes with tryptophan metabolism, as is seen in a number of areas of India. Alcoholism, diarrhea, gastrointestinal disease, certain drugs, and Hartnup Disease can also cause pellagra.

Pellagra can be detected by observation of progressively deteriorating skin as the disorder becomes increasingly severe. The first stage of this disorder is an increased photosensitivity, causing a rash that resembles a sunburn. This rash is usually symmetrical and may form blisters. Next the skin thickens and becomes pigmented and can itch, crack or bleed. Areas affected include the arm, backs of hands, feet, and legs, as well as scrotum and pressure points. The cheeks, nose, forehead and front of the neck also form a ‘butterfly pattern’ of affected skin (also known as ‘Casal’s necklace’). The lips and gums are also prone to cracking and becoming sore.

Other problems faced by those with pellagra include a poor appetite (perpetuating the lack of nutrition that caused the disease), nausea and vomiting. Glossitis, or inflammation of the tongue, is also common, causing a beefy red appearance. In addition, weakness of muscle, depression, confusion, irritability, anxiety, and psychosis are all caused by pellagra.
Pellagra can be treated rather quickly. Nicotinamide or Niacin consumption can begin to remedy the sickness after two days of treatment. Increased consumption of protein and vitamin B can also be effective in correction of malnutrition.

Treating skin properly by wearing protective clothing, using sunscreen and avoiding UV radiation is effective in minimizing irritation caused by pellagra. Certain topical creams can also be helpful in reducing damage to skin from this disease.

Hawk, John L., and Paul G. Norris. “Abnormal Responses to Ultraviolet Radiation: Idiopathic.” Dermatology in General Medicine. Fourth ed. 2 vols. New York: McGraw-Hill, Inc., 1993.

12. Pemphigus

Pemphigus erythematosus (PE), also known as Senear-Usher syndrome, is an uncommon autoimmune disease that causes the skin to blister. It is one of six forms of Pemphigus Foliaceus (PF), which causes many types of blisters yet is relatively benign.

Pemphigus erythematosus usually has a slow onset but eventually causes the skin to develop blisters that tend to crust, ooze and form scales. Besides for the formation of blisters, PE can also cause the skin to form a tender and red ‘butterfly pattern’ across the nose. Additionally, if left untreated this disease can result in infection, scarring, and the loss of temperature control.

Although many factors can cause the blisters to form, the skin is often particularly sensitive to sunlight. Most commonly affected areas are those that have been continuously exposed to sun such as the face, scalp, back and chest. A lack of blisters on mucous membranes such as the eyes and mouth is a useful hint in differentiating PE from other forms of PF.

This disease is caused by an abnormal reaction of particular antibodies, which in the case of PF disorders attach to desmosomes that connect skin (epidermal) cells. When a person has a form of PF, however, these bridges are destroyed and the cells become surrounded by fluid. This fluid results in blisters that are so close to the surface of the skin they break and ooze easily.

Pemphigus erythmatosus affects people of all races, both males and females. Often its victims are between 50 and 60, but rarely is it found in children. Internationally, there are 0.5-3.2 people per 100,000 with a form of pemphigus, but a very small percentage of these people have pemphigus erythmatosus.

Treatment is not always necessary in patients with Pemphigus erythmatosus as the disease often enters into remission over time. Otherwise, systemic steroids can be helpful in fighting the disease. For skin management a combination of topical cream and antibiotics are often very effective. To prevent outbreaks it is important to protect the skin from irritants such as UV Radiation by applying sunscreen to uncovered areas, wearing protective clothing, and avoiding exposure to sunlight.

13. Polymorphic Light Eruption

The most common disorder found in people with exaggerated photosensitivity is Polymorphic Light Eruption (PLE). This condition usually manifests itself before age 30, with women developing the disorder at an earlier age than men. Women are also two to three times more likely to develop PLE at all. Even though the disease has been found in people of all skin types, those who are fair-skinned are most likely to experience PLE.

Those with PLE often develop lesions that first appear in the spring and harden by the summertime due to an increased tolerance of sunlight. The rash formed is usually symmetrical and can develop after being exposed to the sun for 30 minutes or more.

The skin eruptions produced by PLE can take many forms. The most common outbreak consists of small pink or red dots (2-5mm) found on the arms, legs or chest, while marks that resemble insect bites can also develop. If the rash is protected from a second exposure during the days following its initial appearance, it will often disappear completely within weeks. However, if the affected area is exposed once again to UV radiation, the rash can become even more severe. For some people a new rash can form every time the skin is exposed to sunlight, even during the winter.

Prevention of PLE outbreaks is not well known, but by using correct behaviors for sun protection one can minimize the extent to which the rash spreads. This includes avoiding sunlight as often as possible and using high SPF (15+) sunscreen to cover any exposed areas or patches of skin that have been affected by PLE. In addition, wearing clothes that have been tested to prevent UV penetration can be very effective in protecting oneself from the dangers of sunlight.

Treatment for Polymorphic Light Eruption includes a number of oral medications such as steroids, polypodium leucotomas, beta carotene, and hydroxychloroquine. Ultraviolet treatment can also be effective if conducted on an annual basis, before UV radiation peaks in the summertime. In this technique the skin is exposed to increasing amounts of UVA radiation by a dermatologist in a controlled setting.

Hawk, John L., and Paul G. Norris. “Abnormal Responses to Ultraviolet Radiation: Idiopathic.” Dermatology in General Medicine. Fourth ed. 2 vols. New York: McGraw-Hill, Inc., 1993.

14. Pseudoporphyria

Pseudoporphyria is a disorder that causes skin rashes characterized by blistering, scarring, and fragility. These aggravators include excessive UVA radiation, particular medications, and utilization of haemodialysis in certain patients. Lesions can take months before subsiding and will sometimes result in permanent scars where the rash previously appeared.

Pseudoporphyria has an appearance which is very similar to porphyria cutanea tarda (PCT), but differs in the underlying biochemistry that causes the disease.

Men and women are equally likely to develop pseudoporphyria, just as the disease has been found in people of all races and ages. In younger children, however, the illness is more likely to mimic erythropoietic porphyria (EPP) rather than PCT. This form of pseudoporphyria is the result of naproxen use in treatment of juvenile rheumatoid arthritis.

The best treatment for pseudoporphyria is the removal of any irritant which may cause outbreaks to occur. This includes using alternative medications if possible when a diagnosed drug causes a patient to develop lesions. In addition, sunlight and UV radiation should be actively avoided. This should also be supplemented by wearing protective clothing with long sleeves and a hat, as well as with application of a high SPF sunscreen on all exposed areas.

15. Psoriasis

Psoriasis is a commonly inherited genetic disorder. It is chronic and causes the skin to form inflamed and edematous (or fluid filled) symmetric patches with scales that are silvery-white. Psoriasis also causes a painful or itchy rash on areas such as the scalp, trunk, and limbs, and can also damage nails and joints. This rash tends to become more intense as time progresses without treatment for the disease, resulting in deterioration of pre-existing rashes and reddening of skin in small patches. Those with psoriasis commonly have viral infections or throat infections which cause outbreaks of red dots on the trunk, arms and legs.

Psoriasis is very widespread in the United States, where 2.0% – 2.6% of people suffer from the disorder. However, it is most common in Caucasians and females that are living in cooler regions. While 10-15% of cases are found in people aged 10 years or younger, the average age at which the disease sets in is 28.

Psoriasis rashes can be instigated by various forms of stress. Wounds are often the location of psoriasis outbreaks that surround the injury until it heals. Hormones are also connected to the disease as lesions are common following puberty and during pregnancy. Certain medications, alcohol, and smoking are also likely to cause flares of psoriasis.

While sunlight can help a large percent of those with psoriasis, a small portion of those with the disorder will have a negative reaction towards UV radiation. Such people are photosensitive and can be irritated by sunlight, especially in those areas most exposed to the sun such as the hands, neck, and face. It is crucial for these people to avoid sunlight in order to prevent outbreaks. High SPF sunscreen and protective clothing are also very helpful in protecting against aggravation by UV Radiation.

Psoriasis has no known treatment but does occasionally to fade on its own. Often rashes will enter remission for a number of years and then relapse at a later time. Skin management for psoriasis can often be achieved with the help of topical steroids, coal tar, dithranol, and calcipotriol. Phototherapy as well as self-injected biologics such as Enbrel, Amevive, and Humira can all be effective tools in minimizing the extent of an outbreak, but they do not eliminate the disease completely.

16. Rosacea

Rosacea is a common disorder found in an estimated 14 million Americans. This disorder causes redness of the skin on the nose, cheeks, forehead and chin. In more severe cases the neck, ears, chest, and scalp may also be affected. As severity and lack of treatment progress, the disease can cause skin to form red bumps, or papules, and pus-filled pimples. The level of intensity of the disease differs between patients, with some cases being constant while others are recurrent or fading.

Those with rosacea commonly overlook it during its early stages as it can be confused as being acne or a simple tendency to blush often. Additionally, common features of rosacea include persistent flushing and the appearance of capillaries near the skin’s surface. Less common features of affected skin include dryness or roughness, increased sensitivity (especially to sun and spicy foods), and inflammation of the face. In severe cases the nose becomes swollen as the tissue it is comprised of expands, a condition known as rhinophyma.
Rosacea tends to afflict women more than men, although men that do have the disorder often have more severe cases. People who are between 30 and 60 or those with lighter skin are most likely to have rosacea.

The severity of rosacea can vary, resulting in a broad spectrum of potential treatments for each case. Medication and surgery offer possible ways to correct facial disfigurements due to rosacea. Useful medications include tetracycline, cotrimoxasole or metronidazole, which minimize swelling of facial skin. In addition, topical treatments that reduce inflammation or flushing can be helpful. Surgery is most effective in correcting disfiguration caused by rhinophyma. Laser surgery can be used to treat telangiectasias, which are the appearance of small red capillaries on the surface of the skin.
It is also very important for patients to minimize UV irritation of the skin by avoiding direct sunlight, hot showers, spicy foods, oily facial products and alcohol. Use of sunscreen and wearing protective clothing can also minimize the affects of the sun on exposed areas.

Hawk, John L., and Paul G. Norris. “Abnormal Responses to Ultraviolet Radiation: Idiopathic.” Dermatology in General Medicine. Fourth ed. 2 vols. New York: McGraw-Hill, Inc., 1993.

17. Rothmund-Thomson Syndrome

Rothmund-Thomson syndrome (RTS), also known as poikiloderma congenitale, is a rare genetic disease that follows an autosomal recessive pattern of inheritance. It is characterized by commonly appearing red rashes, a predisposition to skin cancer and formation of cataracts at a young age. Those that suffer from this disease often have skeletal dysplasias, or abnormal growth of cartilage and bones, resulting in what is commonly identified as dwarfism. In addition, osteosarcoma, the most common malignant bone cancer, also occurs in patients with this disorder.

Photosensitivity is found in approximately 30% of patients.The above-mentioned rash is the symptom found most often in those with the disease. Infants between three and six months old develop red patches and fluid filled (edematous) areas of skin that are covered in scales. This rash first forms on the cheeks, spreads to other parts of the face and then extends to the body’s limbs. In addition, the affected skin tends to develop blisters. After a number of years the rash transforms into poikiloderma, which is characterized by atrophy, telangiectasias (spider veins), and changes in the skin’s coloring. Additionally, the red patches often become red-brown lesions that are common on the face, extensor extremities and buttocks. To a lesser degree they also appear on the chest, abdomen and back.

Other symptoms of this syndrome include pointed lesions found on the elbows, knees, hands, and feet at puberty, underdeveloped nails, thinning hair and dental abnormalities. Disproportionate hands and feet, skeletal abnormalities infertility and underdeveloped genitalia and secondary sexual traits are all common features.
Rothmund Thomson syndrome’s genetic origins make it impossible to treat the disease, but protection of the skin is crucial to managing the disease. This can be done by avoiding sunlight, wearing protective clothing, and through application of high SPF sunscreen. Because those with RTS are more likely to form cancerous tumors, it is important that the skin is checked regularly for any growths. Regular appointments should also be made with an orthopedist, endocrinologist, and a hematologist/oncologist in order to monitor any changes that may take place within the body.

18. Solar Urticaria

Solar urticaria is a rare disorder that produces a rapid and abnormal response to UV radiation. Upon being exposed to sunlight the skin wheals as it becomes red, swollen, and will often itch or burn. After exposure to the sun for only five to ten minutes a rash can appear, but will normally subside within a few hours, provided that further exposure to sunlight is avoided. All areas of the skin are susceptible, yet the most commonly affected parts are those that are normally covered by clothing but have been exposed to light. In particular, skin that has been bruised is most vulnerable.Besides for swollen skin and erythema (skin that is red and inflamed), patients suffering from solar urticaria sometimes experience headaches, nausea, difficulty breathing, faintness and syncope. These additional reactions are due to a loss of fluid from the cells that have caused swelling. This is most common when the area of the skin infected by a rash is widespread.

The disorder is more common in females than males and often appears for the first time when the patient is between 20 and 40 years old, although cases have been reported at much younger ages. The disorder has been observed in some patients to remain for many years after its onset, but in others it enters into remission or decreases in severity as the patient ages.

A treatment of the disorder has not been found, so utilizing proper sun protection habits and avoiding direct sunlight can be crucial in preventing outbreaks. In addition, oral antihistamines are useful in minimizing the swelling and itching of affected areas, but do not completely eliminate outbreaks. For severe cases desensitization by phototherapy conducted by a dermatologist can be effective. In this technique the skin is exposed to increasing amounts of UVA radiation in a controlled setting, a solution that can be helpful but is short-lasting.

Hawk, John L., and Paul G. Norris. “Abnormal Responses to Ultraviolet Radiation: Idiopathic.” Dermatology in General Medicine. Fourth ed. 2 vols. New York: McGraw-Hill, Inc., 1993.

19. Xeroderma Pigmentosum

Xeroderma pigmentosum (XP) is a very rare disease with an autosomal recessive inheritance pattern. It can be fatal as it causes a high sensitivity to ultraviolet radiation (photosensitivity), causing those with the disorder to develop potentially malignant tumors much more often than the normal population does. The skin also ages rapidly as a result of this disorder and can become discolored.The damage of DNA by UV Radiation is a common phenomenon that occurs on a regular basis. In healthy individuals, however, the DNA also has certain factors and proteins that quickly repair this DNA before it can replicate and create faulty proteins that are needed in the body, become cancerous or enter into apoptosis (cell suicide). People with XP, however, have a malfunction of these genes and therefore cannot repair damaged DNA. The disease can differ in its level of severity, based upon the particular gene that is causing the disease, as seven forms (given the names XPA, through XPG) of the disease exist.

Xeroderma pigmentosum progresses through three stages in which the patient’s health progressively deteriorates. A person with XP is born with skin that appears healthy and without any symptoms of the disease. At 6 months old, however, erythema (a red inflammation of the skin), scaling, and freckles are all observed on skin that has been exposed to UV radiation. Often this includes the neck and lower legs, but can also extend to the trunk. During these early years the characteristics tend to fade during the winter but become permanent as a patient grows older.

With stage two comes the development of poikiloderma in which the skin atrophies, becomes overly or insufficiently colored, and telangiectasia (a dilation of capillaries causing red blotches on the skin) can be seen. This commonly occurs on exposed skin but can spread to non-exposed areas as well.

At stage three, which can set in at an age as young as 4-5 years old, cancers such as squamous cell carcinomas, malignant melanoma, basal cell carcinoma, and fibrosarcoma begin to form mostly on exposed skin.

XP is also characterized by poor vision, or more specifically a sensitivity to sunlight or conjunctivitis. In addition, malignant growths on the eyes, neurological disorders including spasticity and mental retardation, and short stature are all common traits of people with the disorder.

Internationally approximately 1 person per 250,000 has XP, most commonly in the specific forms of XPC and XPD, but XPA is very rarely acquired. In Japan, however, approximately 40% of those with the disease have it in the form of XPA. In terms of sex, men are equally as likely as women to get the disease, just as people of all races are equally likely to acquire the disease. Most often XP is diagnosed in infants aged one to two years old after they are observed to burn very rapidly upon their first exposure to sunlight.

As mentioned, this genetic disease follows an autosomal recessive pattern, which means that two copies of the gene are required in order for someone to have XP. Thus both parents must have a copy (making them carriers) of the disease in order for it to be passed to their children, who have a 1 in 4 probability of acquiring the disease. Because the parents are only carriers, they will not show any symptoms of XP and a family history of the disease is often difficult to identify.

Those with xeroderma pigmentosum under 20 years old are at a risk level 1,000 times that of the normal population of developing either nonmelanoma skin cancer or melanoma. Metastatic malignant melanoma and squamous cell carcinoma also form as a result of XP. Skin cancer appears at an average age of 8 years old in XP patients, as opposed to 60 in those without the disease.

No treatment has been identified for those diagnosed with this disorder. The most important preventive measure to take is minimization of developing skin cancer. This can be done by avoiding as much sunlight as possible and covering any exposed areas with a high SPF sunscreen. In addition, protective clothing including long sleeves, pants, wide brimmed hats and sunglasses should be worn.

Aside from direct protection from UV radiation, a patient with XP must have their skin checked every three to six months for growths and any suspicious area must be tested for cancer. If a tumor is found, surgery should be utilized to remove these dangerous growths. Tests for vision impairment and neurological disorders should also be conducted often to manage any degradation to these systems. Cryotherapy and 5-fluorouracil cream should be used to treat solar keratoses. Isotretinoin, a vitamin A derivative, can also be helpful in preventing the growth of new tumors.

If such precautions are taken under a doctor’s supervision then a patient with xeroderma pigmentosum has the potential to live until middle age. However, if the disease is undetected death can occur at a young age due to the unimpeded growth of cancer.


We unexpectedly found that the effect of CK1i on circadian phase differs between nocturnal mice and diurnal NHPs due to their different levels of photosensitivity: Light attenuates the effect of CK1i more strongly in NHPs than in mice. Such a strong attenuating effect of light on a drug-induced phase delay is expected to exist in humans as their light PRC has a large magnitude of the advance zone (St Hilaire et al, 2012 Ruger et al, 2013 ). Thus, the phase delay induced by melatonin would also be expected to be strongly attenuated by light. This would explain its weak effectiveness in treating ASPD and jetlag after westward travel in a daylight cycle (Sack et al, 2007 Zhu & Zee, 2012 Spiegelhalder et al, 2017 ). These results indicate that such interspecies difference in photosensitivity should be considered when translating the efficacy of clock-modulating drugs from nocturnal mice to diurnal humans.

Our systems chronopharmacology model based on experimental data from NHPs and humans predicts that a regimen reflecting a patient's individual circadian phase can achieve a more precise therapeutic effect than a non-circadian-based regimen. This may explain why the current circadian-based treatment can alleviate sleep disorders (Zhu & Zee, 2012 Sletten et al, 2018 ). However, our model predicts that even if the circadian phase of patients is similar, their response to CK1i can be considerably different depending on the molecular cause and the environmental lighting condition (Fig 4A–D). We found that such variability in the CK1i effect is mainly due to altered PER2 abundances (Figs 4C–E and EV5B–F). While the interspecies difference in PER2 abundance has not been investigated, it may contribute to the interspecies variability in the CK1i effect (Figs 1E–G and 3A). Furthermore, the interspecies difference in the phase of PER2 rhythms (Vosko et al, 2009 Zhang et al, 2014 Millius & Ueda, 2018 Mure et al, 2018 ), which leads to the interspecies difference in PER2 abundance when dosing occurs, could also be the source of the interspecies variability in the CK1i effect. It would be interesting to investigate such a relationship between the effect of CK1i and PER2 abundance, and extend this to other clock-modulating drugs and their target molecules (e.g., KL001 targeting CRY Hirota et al, 2012 ). Furthermore, as PER2 regulates the stability of p53, a key tumor suppressor (Gotoh et al, 2016 ), altered PER2 levels depending on genetics and environmental lighting conditions could vary the level of p53 as well. This may also explain the large inter- and intrapatient variability in the chronotherapy of antitumor drugs (Altinok et al, 2009 Levi et al, 2010 ).

Our work indicates that patient-specific molecular and lifestyle information should be integrated to achieve a desired therapeutic effect of clock-modulating drugs (Fig 4B–D). However, because obtaining such information can be challenging, we developed an adaptive chronotherapeutics, which identifies the precise dosing time to achieve normal circadian phase by tracking the patient's drug response (Figs 5A and EV6A and B). This adaptive chronotherapeutics requires a precise quantification of the drug-induced circadian phase shift in daily life. Recently, to overcome the insufficient accuracy of actigraphy and labor-intensive measurement of dim light melatonin onset (Duffy & Dijk, 2002 Ancoli-Israel et al, 2003 ), various methods have been developed, which are based on the metabolite timetable (Kasukawa et al, 2012 ), one-time phase estimation (Wittenbrink et al, 2018 ), or sleep-tracking using mobile phone (Walch et al, 2016 ). With these advances, the adaptive chronotherapeutics could play a critical role in incorporating biomarker data and providing real-time patient-tailored chronotherapy via smart devices (i.e., digital medicine) (Elenko et al, 2015 ).


Patients may develop photophobia as a result of several different medical conditions, related to the eye, the nervous system, genetic, or other causes. Photophobia may manifest itself in an increased response to light starting at any step in the visual system, such as:

  • Too much light entering the eye. Too much light can enter the eye if it is damaged, such as with corneal abrasion and retinal damage, or if its pupil(s) is unable to normally constrict (seen with damage to the oculomotor nerve).
  • Due to albinism, the lack of pigment in the colored part of the eyes (irises) makes them somewhat translucent. This means that the irises can't completely block light from entering the eye.
  • Overstimulation of the photoreceptors in the retina
  • Excessive electric impulses to the optic nerve
  • Excessive response in the central nervous system

Common causes of photophobia include migraine headaches, TMJ, cataracts, Sjögren syndrome, mild traumatic brain injury (MTBI), or severe ophthalmologic diseases such as uveitis or corneal abrasion. [6] A more extensive list follows:

Eye-related Edit

Causes of photophobia relating directly to the eye itself include:

    [7][8] drugs may cause photophobia by paralyzing the iris sphincter muscle. [citation needed] [9][8][8][8] of the eye [8][10][8][8][11]
  • Disruption of the corneal epithelium, such as that caused by a corneal foreign body or keratitis[8][8][8]
  • Eye trauma caused by disease, injury, or infection such as chalazion, episcleritis, keratoconus, or optic nerve hypoplasia[8] , or congenital glaucoma[8][8] has been associated with photophobia [12][8] [citation needed] (naturally or chemically induced) [9] of the cornea or sclera [8][8]

Nervous-system-related Edit

Neurological causes for photophobia include:

    disorders [13][14][8] including Myalgic encephalomyelitis[15][8]
  • Trigeminal disturbance causes central sensitization (hence, multiple other associated hypersensitivities. Causes can be bad bite, infected tooth, etc. [16] , where photophobia can sometimes precede the clinical diagnosis by years [17][18] of the posterior cranial fossa[8] along with many symptoms.

Other causes Edit

Treatment for light sensitivity addresses the underlying cause, whether it be an eye, nervous system or other cause. If the triggering factor or underlying cause can be identified and treated, photophobia may disappear. Tinted glasses are sometimes used. [32]

People with photophobia may feel eye pain from even moderate levels of artificial light and avert their eyes from artificial light sources. Ambient levels of artificial light may also be intolerable to persons afflicted with photophobia such that they dim or remove the light source, or go into a dimmer lit room, such a one lit by refraction of light from outside the room. Alternatively, they may wear dark sunglasses, sunglasses designed to filter peripheral light, and/or wide-brimmed sun hats or baseball caps. Some types of photophobia may be helped with the use of precision tinted lenses which block the green-to-blue end of the light spectrum without blurring or impeding vision. [33] [34]

Other strategies for relieving photophobia include the use of tinted contact lenses and/or the use of prescription eye drops that constrict the pupil, thus reducing the amount of light entering the eye. Such strategies may be limited by the amount of light needed for proper vision under given conditions, however. Dilating drops may also help relieve eye pain from muscle spasms or seizure triggered by lighting/migraine, allowing a person to "ride out the migraine" in a dark or dim room. A paper by Stringham and Hammond, published in the Journal of Food Science, reviews studies of effects of consuming Lutein and Zeaxanthin on visual performance, and notes a decrease in sensitivity to glare. [35]

Photophobia may preclude or limit a person from working in places where offensive lighting is virtually ubiquitous (e.g., big box stores, airports, libraries, hospitals, warehouses, offices, workshops, classrooms, supermarkets and storage spaces), unless the person is able to obtain a reasonable accommodation like being allowed to wear tinted glasses when the employee dress code prohibits such glasses otherwise (which may be required to be provided by an employer under the Americans with Disabilities Act). Some people with photophobia may thereby be better able to work at night, or be more easily accommodated in the work place at night.

Outdoor night lighting may be equally offensive for persons with photophobia, however, given the wide variety of bright lighting used for illuminating residential, commercial and industrial areas, such as LED (light-emitting diode) lamps. [36] [37]

Acne Medications That Cause Photosensitivity

Many acne medications can cause photosensitivity. While using them, your skin is more likely to burn, even if you typically don't. And these burns can be much more severe than a run-of-the-mill sunburn—think blistering and peeling.

It's important to know that simply using these medications doesn't automatically mean you'll burn to a crisp in the sun. But it absolutely raises the risk of sunburn, so make sure you adequately protect yourself from the sun's damaging rays.

Before heading outside, check to see if your acne medication is on the list.

Topical Retinoids

Topical retinoids are often prescribed to treat acne, and they're one of the worst photosensitizing offenders. Topical retinoids include the medications Retin-A (tretinoin), Retin-A Micro, Differin, and Tazorac. They also include medications that contain a topical retinoid like Ziana and Epiduo.

Benzoyl Peroxide

It doesn't matter if it's a prescription benzoyl peroxide medication (like BenzaClin or Onexton) or an over-the-counter product you picked up at the drug store. Benzoyl peroxide can cause photosensitivity too.   A plethora of anti-blemish skincare products contain benzoyl peroxide, so make sure you check the active ingredients of the acne treatment products on your shelf.  


It's not just topical medications that can make you more sensitive to the sun. Certain oral medications, like oral antibiotics, can do the same. Doxycycline is the most likely to cause photosensitivity, but tetracycline, minocycline, and erythromycin can too.  


Isotretinoin is arguably the best treatment we have for severe acne. It does come with possible side effects, including photosensitivity. Your dermatologist will go over all potential side effects with you, and how to best manage them.

Alpha Hydroxy Acids (AHAs)

These are also OTC ingredients that are not only found in anti-blemish skincare products but in anti-aging and skin brightening products too. Look for alpha hydroxy acid, lactic acid, tartaric acid, or glycolic acid in the ingredient list.

Acne Treatment Procedures

But acne medications aren't the only culprits that cause photosensitivity. Certain acne treatment procedures can also increase your skin's sensitivity to the sun. This includes microdermabrasion, chemical peels, and some laser treatments.

What Are the Side Effects from Combining These Drugs with Laser Treatments?

The degree of the side effects varies, but some of the most common types are hyperpigmentation (the discoloration of the skin), blisters, and mild burns. While most of these side effects are hardly more than a mild irritation, there is a chance that some reactions can be worse.

Some people might suffer from a phototoxic reaction, which looks and feels like an extreme sunburn. It’s caused when the UV laser activates the chemicals in the medication, which have already been absorbed into the body’s system. The pain and irritation are mild and temporary, but can get worse over time and even damage the skin if you continue treatments without stopping the medication.

Another more serious reaction is a photoallergic reaction, which occurs when the UV laser actually changes a drug’s chemical structure within the skin. This causes the immune system to attack the drug, making the skin swell up and itch. While this is a temporary side effect, it can lead to more permanent skin conditions such as eczema or dermatitis.

How do tetracyclines work?

As antibiotics, tetracyclines interfere with protein synthesis of susceptible bacteria.

They are also anti-inflammatory agents.

  • They inhibit matrix metalloproteinases (MMPs), hydrolases and phospholipase A2 — these enzymes are active in dermal inflammatory skin disorders.
  • They reduce production of pro-inflammatory cytokines such as TNF -a, IL-1B, and IL-6.
  • They are antioxidants, reducing free radical production and nitric oxide.
  • They inhibit angiogenesis and granuloma formation.

Preventative Measures and Recommendations

If you are taking any of the drugs thought to cause photosensitivity, your best bet is to avoid sun exposure. If you must venture outside, minimize your exposure in terms of duration, time of day, and clothing you choose to wear. Take extra precautions to shield yourself from the sun. Light-colored clothing, long-sleeve shirts, long pants or skirts, sunglasses, sunscreen that is rated SPF-30 or higher, and a wide-brimmed hat are important protection, but they will not totally block UV radiation.

Sunscreens containing physical blockers, such as zinc oxide and/or titanium dioxide, are recommended as a preventive measure against sun sensitivity.