Polymorphous light eruption is a skin rash that develops on areas of the body that have been exposed to sunlight. The condition is sometimes referred to as “sun allergy.” It is seen most often in women with fair skin and often develops between the ages of 20 to 40 years.
Individuals with polymorphous light eruption develop an itchy rash when exposed to the sun’s ultraviolet rays. Symptoms typically surface within 4 days after sun exposure and may include the appearance of small bumps, blisters, redness, scaling, itching, hives or swelling. Symptoms are seen only on parts of the body that are exposed to the sun and vary from person-to-person. It is not unusual for someone to experience a combination of symptoms.
If you notice rash or skin reaction following sun exposure, it is important to see your dermatologist. Some cases of polymorphous light eruption may be triggered by a response to certain medications such as tetracycline and sulfa antibiotics. Chemicals found in fragrances, lotions and other products can also make the skin more likely to react to sunlight.
Diagnosing polymorphous light eruption may be as simple as examining the skin. Your dermatologist may also conduct tests using an ultraviolet lamp, skin patch testing or skin biopsy.
Treatment of polymorphous light eruption includes steroid creams or pills, phototherapy to sensitize skin to ultraviolet light and anti-malarial medications to reduce inflammation. Studies have also shown polypodium leucotomos, an antioxidant derived from fern leaves, appears to be effective in preventing polymorphous light eruption symptoms in some individuals.
To reduce the risk of polymorphous light eruption symptoms, it is advisable to avoid midday sun exposure (between the hours of 10 a.m. and 3 p.m.), generously apply a broad-spectrum sunscreen with an SPF of 30 before heading outside, wear sun-protective clothing and hats and seek areas of shade when outdoors.