What Is Polymorphous Light Eruption? Treat And Prevent It

Woman with polymorphous light eruption in the sun

Polymorphous Light Eruption

Polymorphous light eruption, or PLE, is the most common skin disease caused by sunlight. It is also called polymorphic light eruption (PMLE). Other variants include juvenile spring eruption and benign summer light eruption. PLE is not the same as sunburn. PLE arises spontaneously in people who are sensitive to ultraviolet light and is characterized as one type of photodermatosis. It usually manifests as an itchy rash—little red bumps or slightly raised patches of skin—after sun exposure in people who are photosensitive. While the rash can take different forms in different people, it usually appears the same in each individual. PLE is more likely to appear when the skin isn’t used to sunshine, such as in spring or on a sunny holiday. While the rash can go away on its own, it tends to reappear after the first incident. PLE is not harmful or infectious, but may be unsightly and embarrassing.

Symptoms

The name polymorphic eruption means a rash that has many different forms. The rash usually appears on the parts of the skin exposed to sunlight—the head and neck, chest, and arms—but which might not be exposed year-round. The face isn’t necessarily affected.

An itchy or burning rash may appear anywhere from hours (or even minutes) up to two to three days after sun exposure. The rash may consist of erythematous papules, papulovesicles, plaques and/or lesions similar to eczema or erythema multiforme, and may be confused with hives. It can look like dense clusters of small red bumps and raised rough patches. Some lesions may have fluid-filled blisters. An eruption may last up to two weeks but heal without scarring if sunlight is avoided. However, if the skin is exposed to additional sunlight before the rash has healed, the condition usually gets much worse.

Symptoms may only occur rarely, or may happen every time an individual’s skin is exposed to sunlight. But for most people with sun sensitivity, the rash develops after several hours outside on a sunny day. The light eruption can range from very mild to severe.

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Less commonly, secondary symptoms may include flu-like symptoms, fever, skin sensitivity, body and muscle aches, dizziness/disorientation, exhaustion, and vision impairment. These symptoms may be the result of any associated sunburn rather than the PLE itself.

You should see a doctor if you have a rash without an obvious cause, as a number of conditions—including serious diseases—can cause skin rashes with similar appearances to PLE. You should also seek medical care if your rash is widespread, painful, and/or accompanied by a fever. If there is doubt, it’s important to get a prompt diagnosis and appropriate treatment.

Who Is Affected

Polymorphous light eruption is most common in young adult women who live in temperate climates, such as North America and Europe, but also affects men and can affect children. PLE onset does seem to happen at an older age in men than in women. PLE occurs most often during the spring and summer. It affects all ethnicities and skin types, and is prevalent in approximately 10-20% of lighter-skinned populations; it may be even more common in individuals with darker skin. And the prevalence goes up when lumping photodermatoses together—including, for example, solar urticaria, photoallergic dermatitis, hydroa vacciniforme, chronic actinic dermatitis, erythropoietic porphyria, and lupus erythematosus. There is a genetic tendency for PLE to occur. Patients can also experience PLE during phototherapy treatments for other skin conditions like psoriasis and dermatitis.

Causes

For people who have shown symptoms of polymorphous light eruption previously, 30 minutes or less of sun exposure may be enough to cause a reaction. It can be triggered by visible sunlight and both UVA (ultraviolet A) and UVB (ultraviolet B) rays, tanning beds, and even exposure to fluorescent lighting. Because UVA rays provoke PLE, symptoms may even appear after sun exposure through a glass window or thin clothing. This also means that standard sunscreen lotions (that don’t protect very well against UVA rays) may not prevent a reaction in people who are photosensitive.

The mechanism of PLE is not well understood. It is thought to be caused by a type IV delayed hypersensitivity reaction by the immune system to an allergen produced by the body—in this case, in response to the damage from sun exposure, resulting in skin inflammation. In this instance, ultraviolet radiation leads to impaired T-cell function and an altered production of cytokines, reducing normal UV-induced immune suppression in the skin.

PLE tends to run in families and often people who are affected will have relatives who are also affected. But sensitivity to sunlight can lessen with repeated exposure. After longer periods without exposure to sunlight, symptoms may appear with exposure. But they may be less likely to appear with repeated exposure to smaller amounts of sunlight. Gradually, some people may become less sensitive over several years or eventually even no longer experience recurring symptoms.

How To Diagnose PLE

Polymorphous light eruption can often be diagnoses by a doctor from a description of the symptoms, the length of the rash, and the history of the individual. A rash that appears hours or within a day or two of light exposure, and that clears after a few days to a week or two, is a common sign. The rash is confined to exposed areas of skin.

Blood tests and a skin sample may also be used to rule out other conditions. Skin biopsies that show PLE are characterized by edema (oedema) and dense perivascular lymphocytic infiltrate. Eczema-like symptoms may also be present. Additionally, phototesting can be used to confirm a diagnosis. This involves provoking a small area of skin with light (usually UVA) to see how the skin reacts.

The most common varieties of PLE present as crops of 2-5 mm red or pink papules. Other presentations include:

  • Red macules (erythema)
  • Erythematous plaques
  • Dry, red patches or plaques (dermatitis)
  • Fluid-filled vesicles (blisters)
  • Pinpoint papules (especially the color of the skin)
  • Lichenoid plaques
  • Target lesions (having a bull’s-eye appearance)
  • Itchy spots confined to exposed areas (prurigo)

Your doctor will also want to rule out other common disorders characterized by light-induced skin reactions. These conditions include:

  • Lupus: Lupus is an autoimmune disease in which the immune system becomes overactive and attacks healthy tissue. PLE and PLE-like symptoms can be the first sign of lupus erythematosus, but this is not commonly the case. Cutaneous lupus erythematosus can be ruled out if direct immune fluorescence is negative.
  • Chemical photosensitivity: A number of chemicals, including oral medications, lotions, fragrances, and sunscreens/sunblocks, can induce skin photosensitivity. In these instances, the skin reacts each time after ingesting or being exposed to a particular chemical.
  • Solar urticaria: Solar urticaria is a sun-induced allergic reaction that causes hives: raised, red, itchy welts of varying sizes that can quickly appear and disappear on the skin.

How To Treat PLE

Polymorphous light eruption usually resolves on its own within a week or two. Since rashes will normally heal if sun exposure is avoided, further treatment may not be necessary.

However, medications or other treatments may be needed to treat persistent cases.

Self-care measures that may decrease the symptoms of PLE, such as itching, include:

  • Using cold compresses: apply a towel dampened with cool water to the affected skin, or take a bath in cool water.
  • Leaving blisters alone: to speed the healing process and avoid infection, leave blisters intact. If needed, you can cover blisters with gauze.
  • Taking pain relievers and anti-inflammatories: Over-the-counter medication such as ibuprofen (Motrin, Advil), acetaminophen (Tylenol), and naproxen (Aleve) may help reduce inflammation, redness, itchiness, and pain.
  • Taking antihistamines: Oral antihistamines can help reduce itching, and avoiding itching is important to help rashes heal.
  • Applying anti-itch cream: an over-the-counter corticosteroid cream such as hydrocortisone (1% hydrocortisone cream) can reduce inflammation and decrease itchiness to help rashes heal.

For more severe or troublesome PLE, your doctor may consider prescribing:

  • Stronger topical corticosteroids than are available over-the-counter
  • Oral corticosteroids
  • Hydroxychloroquine: This is a medication usually used to treat malaria, but is also used to reduce inflammation in the treatment of conditions such as rheumatoid arthritis and lupus.
  • Phototherapy: This is controlled light therapy that exposes your skin to gradually increasing doses of UV light. Usually started in the spring, phototherapy can be conducted for several weeks to decrease your skin’s sensitivity to sunlight. By increasing your resistance to sun exposure, you may be able to prevent or reduce the reaction you normally get when you go in the sun. This decreased sensitivity does wear off over time (such as over the winter), so may need to be repeated each year.
  • Psoralen plus ultraviolet A (PUVA) therapy: PUVA is a type of phototherapy that combines UVA exposure with the administration of a medicine called psoralen. Psoralen makes your skin more sensitive to light, potentially making the therapy more effective. But there are short-term side effects of using PUVA treatment include burning, nausea, headaches, and itching. PUVA may not be recommended though as narrowband UVB phototherapy has been shown to be nearly as effective while also safer and less complicated.

How To Prevent PLE

The key to preventing polymorphous light eruption, and to preventing recurring episodes, is to protect your skin from sun exposure.

To prevent PLE:

Avoid sun exposure

At the very least avoid exposure in the middle of the day when UVB rays are highest in intensity. However, the intensity of UVA rays is relatively unchanged all day (and UVA rays can cause PLE reactions) so limit sun exposure even in the evenings. Also, avoid sun exposure through windows as UVA rays are able to penetrate glass. Be aware that even in the shade, or under an umbrella, surrounding surfaces can still reflect light and indirectly expose your uncovered skin to some UV rays. You will also want to make sure you are getting all the Vitamin D you need from your diet (and supplementation if necessary).

Cover up

Wear a hat and sunglasses, long-sleeve shirt and pants, and cover as much exposed skin as possible. Darker, thicker clothing provides better protection than thinner, lighter-colored clothing. If rashes from PLE are common on your hands, wear gloves while driving during the day.

Use sunscreen lotion prior to sun exposure

Apply it liberally, especially to your face, nose, ears, and neck, and also your chest, shoulders, and back if exposed. Broad spectrum sunscreens/sunblocks can block some percentage of UVA rays, although they don’t provide complete protection so you will still be susceptible to PLE reactions. Lip balm will help provide some protection for your lips. Reapply sunscreen lotion and lip balm every few hours while in the sun, and more frequently if your skin gets wet or sweaty.

Use an antioxidant nutritional supplement

Sunsafe Rx is a natural nutritional supplement made with ingredients that have been clinically shown to help prevent sun damage to your skin. These ingredients have also helped those with sensitive skin prevent allergic reactions to the sun. Eating foods with these antioxidants can also help: for instance, tomato sauce/paste (with lycopene) and other colorful vegetables with antioxidants such as lutein and zeaxanthin, eggs (with the yolk), and fish with omega-3 fatty acids.

Try gradual sun exposure

Over days, weeks, and months, some people with PLE have success slowly exposing their skin to increasing amounts of sunlight. You may start in the spring and continue through the summer–maybe with just a few minutes of sun exposure to start. Then two days latter a few more minutes. Be careful and don’t overdo it; let your personal experience with how much light causes your reaction guide you. Every other day or every few days you may be able to slightly increase the amount of sun exposure you receive and slowly build up a tolerance/resistance to sunlight. However, just realize that every moment you are in the sun does still damage and age your skin. The good goes with the bad; this can’t be avoided. Furthermore, your desensitization to sunlight is normally lost in the winter so starting at the beginning and gradually increasing your sun exposure will probably need to be repeated each spring/summer.

Moisturize your skin

Dry skin can irritate PLE and make it worse. Keep your skin moisturized by drinking plenty of water and using a moisturizer. In particular, apply a moisturizer to any problem areas immediately after showering, and avoid bathing in water that is too warm or hot. Use a mild soap and a non-comedogenic lotion that you know doesn’t irritate your skin.

Prognosis/Outlook

Although there isn’t really a treatment that permanently gets rid of PLE, the outlook is good. Even though rashes may be unsightly and uncomfortable, they normally heal completely. For most people, PLE is a condition that can be managed with lifestyle changes and various over-the-counter treatments and natural remedies.

PLE tends to reoccur each year, but throughout the year, individuals with PLE can usually tolerate more sun exposure as the summer progresses and they build up some resistance to UV rays. This means that individuals can be in the sun longer before they develop a skin reaction, and by staying under this threshold of sun exposure they can prevent reactions. PLE doesn’t usually show up during the winter but can in individuals who are very sensitive to sunlight.

Many people with polymorphous light eruption find that they become less sensitive to sunlight over time. PLE may even clear up on its own, although this is less common. PLE also appears to be less severe in women after menopause.

Clinical Studies Show Natural Ingredients, Taken Orally, Can Help Prevent PLE

There have been some clinical studies on natural ingredients that, when taken orally, help prevent or relieve polymorphous light eruption. In particular, beta-carotene, canthaxanthin, lycopene, and polypodium leucotomos have all shown good clinical results in patients. Here are the summaries from a few of these studies:

Beta-Carotene and Canthaxanthin

In several studies, a combination of beta-carotene (a Vitamin-A precursor) and canthaxanthin (a carotenoid present in foods such as edible mushrooms and many sea foods and similar in structure to beta-carotene) have been shown to aid those with PLE. In the research paper “Light protection and increase of UV tolerance,” the authors conclude:

“For the prevention of photodermatoses, the industry offers broad spectrum absorbents. For internal prophylaxis, oral ingestion of a new preparation containing 25 mg beta-carotene and 35 mg canthaxanthin per dragee, has proved to restore the tolerance of sunlight with polymorphic light eruption, light urticaria, protoporphyria, and other photodermatoses to a considerable degree.”

In another randomized, double-blind, placebo-controlled study, 35 patients took 100mg total daily of a carotenoid preparation of betacarotene and canthaxanthine. Full freedom from sun sensitivity was obtained by 6 people, and partial sun tolerance was induced in an additional 17 people. This means 23 out of 35 people taking the preparation during a summer achieved either partial or total relief from PLE.

Lycopene

In one study, a nutritional supplement containing lycopene, β-carotene, and Lactobacillus johnsonii was administered to patients with polymorphic light eruption to assess whether the nutritional supplement could diminish skin lesions. In the study, 60 patients were given either the nutritional supplement or a placebo, then exposed to ultraviolet A (UVA) light 1x per day for 2 days to induce skin lesions. The results showed that 12 weeks of oral intake of the supplement combination significantly reduced the symptoms of PLE after the first exposure as compared with patients taking placebo. At a molecular level, the supplement combination also reduced the signs of damage from UV light. The conclusion of the research paper was that, “the nutritional supplement provides protection against the development of UVA-induced PLE lesions at clinical and molecular levels.”

Polypodium Leucotomos

A handful of studies have shown polypodium leucotomos is effective at preventing and treating polymorphous light eruption. In one study, 35 patients with PLE were exposed to UVA and/or UVB light both before and after taking polypodium leucotomos for 2 weeks. Of patients that developed lesions prior to taking polypodium leucotomos, 30% no longer produced lesions after taking polypodium leucotomos and being exposed to UVA, and 28% no longer produced lesions after being exposed to UVB. In addition, in the remaining patients, the average amount of UV light it took to elicit polymorphous light eruption after taking polypodium leucotomos increased significantly. This means that oral polypodium leucotomos was beneficial to PLE patients and helped either prevented PLE, decrease the severity of PLE, or increase the amount of sun exposure it took to elicit PLE.

In a second study, 26 patients with polymorphic light eruption and two with solar urticaria were exposed to sunlight both before and after consuming polypodium leucotomos. With polypodium leucotomos there was a relevant and statistically significant reduction of skin reactions. The authors conclude that polypodium leucotomos administration is a safe and effective way to help protect the skin of those with idiopathic photodermatoses (including both polymorphous light eruption and solar urticaria).

Another similar study on 57 people with polymorphic light eruption and solar urticaria was also run. The results showed there was a significant reduction of skin reaction and subjective symptoms in about 74% of patients taking polypodium leucotomos. No side effects were observed. The paper summarizes that polypodium leucotomos’s “complete absence of toxicity combined with its multifactorial protection, makes it an effective and safe treatment for photoprotection in idiopathic photodermatoses [including both polymorphous light eruption and solar urticaria].”

Other Ingredients

Other ingredients, when taken orally, can most likely also help prevent polymorphous light eruption, especially antioxidants that function in similar ways to beta-carotene, canthaxanthin, lycopene, and polypodium leucotomos by preventing free-radical damage in the skin. Since there are other ingredients that have been shown, when ingested, to protect your skin from sun damage, they realistically also probably help prevent PLE. These include the EGCG (epigallocatechin-3-gallate) in green tea, grape seed extract, lutein, astaxanthin, and fatty acids. And there have been a lot of clinical trials that show these ingredients do protect your skin from sun damage. These natural ingredients are also present in a nutritional supplement (a pill taken orally) called Sunsafe Rx that has been shown to help prevent sun damage to your skin.

Summary

Polymorphous light eruption is the most common skin disease caused by sunlight. PLE usually appears as an itchy rash after sun exposure in people who are photosensitive. While the rash can go away on its own, it tends to reappear after the first incident. PLE is not harmful or infectious, but may be unsightly and embarrassing.

Ways to prevent PLE include avoiding sun exposure, covering up when in the sun, using sunscreen lotion prior to sun exposure, using an antioxidant nutritional supplement such as Sunsafe Rx, increasing your sun exposure gradually, and moisturizing your skin.

Ways to treat PLE over the counter include using cold compresses, leaving your blisters alone, taking pain relievers and anti-inflammatories, taking oral antihistamines, and applying anti-itch cream.

If necessary, your doctor may also prescribe stronger topical corticosteroids than are available over the counter, oral corticosteroids, hydroxychloroquine, phototherapy, and/or psoralen plus ultraviolet A (PUVA) therapy.

Ingredients naturally present in foods and plants also may be able to help prevent or relieve PLE. In particular, beta-carotene, canthaxanthin, lycopene, and polypodium leucotomos have all shown good clinical results in patients.

Other natural ingredients have also been shown, when ingested, to protect skin from sun damage, including EGCG (epigallocatechin-3-gallate), grape seed extract, lutein, astaxanthin, and fatty acids. These ingredients are present in a nutritional supplement called Sunsafe Rx that has been shown to help prevent sun damage.

Although there isn’t really a treatment that permanently gets rid of PLE, the outlook is good. You can have clear, healthy-looking skin. Even though rashes may be unsightly and uncomfortable, they normally heal completely. For most people, PLE is a condition that can be managed with lifestyle changes, natural remedies, and various over-the-counter treatments.

References

Indian J Med Res. 2006 Jun;123(6):781-7. Impact of oral vitamin E supplementation on oxidative stress & lipid peroxidation in patients with polymorphous light eruption. Ahmed RS1, Suke SG, Seth V, Jain A, Bhattacharya SN, Banerjee BD. https://www.ncbi.nlm.nih.gov/pubmed/16885600

Front Biosci (Elite Ed). 2009 Jun 1;1:341-54. Pathogenic mechanisms of polymorphic light eruption. Gruber-Wackernagel A1, Byrne SN, Wolf P. https://www.ncbi.nlm.nih.gov/pubmed/19482651

J Drugs Dermatol. 2015 Mar;14(3):254-61. Polypodium leucotomos extract: a status report on clinical efficacy and safety. Winkelmann RR, Del Rosso J, Rigel DS. https://www.ncbi.nlm.nih.gov/pubmed/25738847

Z Hautkr. 1984 Nov 1;59(21):1454-62. [Light protection and increase of UV tolerance]. [Article in German] Wiskemann A. https://www.ncbi.nlm.nih.gov/pubmed/6516510

J Clin Aesthet Dermatol. 2014 Mar;7(3):13-7. Polypodium leucotomos as an Adjunct Treatment of Pigmentary Disorders. Nestor M1, Bucay V2, Callender V3, Cohen JL4, Sadick N5, Waldorf H6. https://www.ncbi.nlm.nih.gov/pubmed/24688621

Photodermatol Photoimmunol Photomed. 2014 Aug;30(4):189-94. doi: 10.1111/phpp.12093. Epub 2014 Jan 2. Prevention of polymorphic light eruption by oral administration of a nutritional supplement containing lycopene, β-carotene, and Lactobacillus johnsonii: results from a randomized, placebo-controlled, double-blinded study. Marini A1, Jaenicke T, Grether-Beck S, Le Floc’h C, Cheniti A, Piccardi N, Krutmann J. https://www.ncbi.nlm.nih.gov/pubmed/24283388

J Am Acad Dermatol. 2012 Jan;66(1):58-62. doi: 10.1016/j.jaad.2010.09.773. Epub 2011 Jun 22. Oral administration of a hydrophilic extract of Polypodium leucotomos for the prevention of polymorphic light eruption. Tanew A1, Radakovic S, Gonzalez S, Venturini M, Calzavara-Pinton P. https://www.ncbi.nlm.nih.gov/pubmed/21696853

Photodermatol. 1985 Jun;2(3):166-9. Oral carotenoid treatment in polymorphous light eruption: a cross-over comparison with oxychloroquine and placebo. Jansén CT. https://www.ncbi.nlm.nih.gov/pubmed/3895186

G Ital Dermatol Venereol. 2011 Apr;146(2):85-7. Oral polypodium leucotomos extract photoprotective activity in 57 patients with idiopathic photodermatoses. Caccialanza M1, Recalcati S, Piccinno R. https://www.ncbi.nlm.nih.gov/pubmed/21505393

Photodermatol Photoimmunol Photomed. 2007 Feb;23(1):46-7. Photoprotective activity of oral polypodium leucotomos extract in 25 patients with idiopathic photodermatoses. Caccialanza M1, Percivalle S, Piccinno R, Brambilla R. https://www.ncbi.nlm.nih.gov/pubmed/17254039

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