You’ve probably heard of the term “sun poisoning” before, which is meant to describe a severe sunburn and resulting reaction, which can include anything from a headache or fever to painful blisters. This is not the same, however, as an actual allergy to the sun called Polymorphous Light Eruption, or PMLE. You probably haven’t heard of this condition unless you’re one of the unlucky ones who has been diagnosed with it, but it’s more common than you think, and it’s acquired over time. Here’s what to know, according to dermatologists.
What is Polymorphous Light Eruption?
“Polymorphous Light Eruption is a skin condition that results from a sensitivity that occurs on sun-exposed areas of skin,” explains Melville, NY dermatologist Kally Papantoniou, MD. “It is a type of autoimmune disease that is triggered by ultraviolet light.”
The UV light creates an itchy rash, which can last from several hours to several days. According to the American Osteopathic College of Dermatology, PMLE is the most common light-induced skin disease. In fact, National Institutes of Health (NIH) research confirms that the condition impacts roughly 10 to 20 percent of the population.
Dr. Goldstein says the rash can be any type of lesion, from small bumps to even blisters. “Usually it presents on the V of the chest, the tops of thighs and the forearms, but can be anywhere sun exposure has occurred. Interestingly though, the rash does not always present everywhere the sun exposure has occurred. Either way, it usually fades over time with sun protection and gradually increased skin hardening via sun exposure.”
What causes it?
“We do not know exactly what causes this abnormal immune reaction to ultraviolet light exposure that results in this rash, but it is more common in women in their 20s and 30s with lighter skin pigmentation, but it can truly occur in anyone,” says Dr. Goldstein. “It can run in families, and therefore may have some genetic component as well. It typically appears with the first intense sunlight exposure of the season, tanning bed use or a winter vacation to a sunny location.”
PMLE can be confused with several more classic autoimmune disorders that also present with sun sensitivity, such as lupus erythematosus or dermatomyositis,” Dr. Goldstein adds. “However, in those situations, usually there are other signs or symptoms of underlying systemic involvement, such as fatigue and joint aches, and there is typically less itching.”
What it looks like:
According to Dr. Papantoniou, PMLE rashes can be polymorphous (meaning they occur in various forms), hence the name of the condition. “Most rashes are red patches and may involve raised areas with scaling,” she explains. “The affected areas will be limited to sun-exposed areas.” Below are two images of PMLE rashes: one on the arm and one on the chest.
In some cases, Dr. Goldstein says it may be difficult to determine if the rash is PMLE or allergic contact dermatitis that results from wearing certain sunscreens that are light exposure–based. “The most common sunscreen ingredient that can cause a photo-induced allergic reaction is oxybenzone, aka benzophenone-3 or BP-3 (the trade names are Milestab 9, Eusolex 4360, Escalol 567, and KAHSCREEN BZ-3).”
How to treat it:
Treatment for PMLE typically involves using cool compresses, lotions that contain menthol, and prescription-strength topical corticosteroids to shorten the duration and relieve symptoms, Dr. Goldstein explains. “If the rash is severe, oral steroids for one to two weeks may be needed.”
“If you are diagnosed with polymorphous lightly eruption, you need to be more careful with sun exposure and you must be diligent about applying mineral-based sunscreens, SPF 50 or higher,” says Dr. Papantoniou. “Also remember to reapply when you are outside for more than an hour in the sun. I recommend wearing sun-protective clothing and seeking shady areas when possible as well.”
Dr. Goldstein adds that the preventive use of a polypodium leucotomos supplement daily (look for the brand name Heliocare) can be helpful in certain individuals who know they tend to have this condition.