Polymorphous Light Eruption
This page is part of Toronto dermatologist Dr. Michelle Levy’s dermatology library. Please read our disclaimer for more information.
Polymorphous light eruption (PMLE) is an allergy to sunlight that affects an estimated 10% of the population. It occurs in individuals of all backgrounds but is most common in people with fair skin. PMLE is more common in cold Northern climates than in warm and sunny ones.
What Does PMLE Look Like?
PMLE is typically composed of intensely itchy red bumps, patches or blisters that develop minutes to hours after sun exposure. Spots are most common on the neck, chest and body; usually the face is not affected. The rash tends to last one to several days.
PMLE typically develops with first onset of sun exposure; it is most common in the spring and tends to be less common as the spring and summer progress. In other words, the skin tends to develop tolerance to sun exposure that takes place from spring to summer. It is common for individuals susceptible to PMLE to develop it when they go south on vacation during the winter.
What Causes PMLE?
PMLE is an acquired allergy to ultraviolet radiation. Susceptibility appears to be genetic.
How is PMLE Treated?
Flares of PMLE are usually treated with topical cortisone creams. Severe outbreaks are sometimes treated with oral or injected cortisones.
Because tolerance often develops to sun exposure, individuals who develop PMLE can receive phototherapy (medical ultraviolet light) prior to a vacation or before the spring. This is called "hardening" and it requires approximately 15 visits to a centre that offers phototherapy. Available treatments do not "cure" PMLE but can prevent, treat or mitigate outbreaks.
Are There any other Changes I can Make that Would be Helpful?
Sun protection is very important. The regular use of a broad-spectrum sunscreen with a high SPF can sometimes prevent PMLE outbreaks. Sun-protective clothing is also an excellent way to try to prevent PMLE.