Polymorphous Light Eruption

What is Polymorphous Light Eruption?

Resulting from exposure to the sun, Polymorphous Light Eruption is a skin rash that’s considered harmless. PMLE usually occurs due to excessive sun exposure or when getting back into the habit of going outdoors after the winter season. It differs from sunburn, although it can also cause itching and slight discomfort. It’s often temporary and usually goes away fairly quickly.

Causes of PMLE

PMLE is caused by exposure to UV (ultraviolet) and visible light. It can result from direct or indirect exposure to sunlight, as from sitting near a sun-exposed window. It may also be caused by exposure to fluorescent lighting. PMLE may be affected by individual immune system reactions, explaining why some people develop the rash and others are unaffected.

What are the Symptoms of Polymorphous Light Eruption?

  • Visible rash (skin discoloration)
  • Small, raised spots
  • Small blisters
  • Itching or a burning sensation

Polymorphous Light Eruption Causes

The causes of polymorphous light eruption are not completely understood. Research is ongoing for this mysterious malady. However, it is known that people who have these rashes are those who have become sensitive to certain aspects of sunlight. One thing especially that affects them is ultraviolet radiation. People who have polymorphous light eruption are sensitive to both UVA and UVA light. However, some are only sensitive to one or the other.

It is not only the sun that can provide ultraviolet radiation. An individual who uses tanning lamps or tanning beds can also develop this sensitivity, which is called photo sensitivity. It affects the immune system in a manner that can cause the rash.

Polymorphous light eruption is also considered to run in families. There are many cases in which several relatives have this skin issue.

How is Polymorphous Light Eruption Treated?

Diagnosis involves visual examination of the rash and may include blood tests or a biopsy to rule out skin cancer or other conditions. PMLE is sometimes confirmed through photo-testing where a small patch of skin is exposed to artificial light to see how it reacts. Symptoms of PMLE often go away after making an effort to minimize sun exposure or when skin becomes accustomed to regular sunlight again.

Treatment may include:

  • Hydro-cortisone cream
  • Corticosteroids
  • Topical ointments
  • Antihistamine tablets (to minimize itching)

Polymorphic light eruption is not an indication of skin cancer and is not contagious. It usually recurs in the same pattern. More common in women and younger adults, PMLE tends to appear on people who live in temperate areas that aren’t excessively hot or cold. Risk of developing PMLE can be reduced by wearing sunscreen with an appropriate SPF level and staying indoors during times when sunlight is strongest.

Polymorphous Light Eruption Prevention

There are a few ways by which you can prevent this medical issue.

Protection from the sun

Cover up with a hat and sunglasses, as well as adequate sunscreen at a level that is recommended by a doctor. The sunscreen will need to be re-applied if you are outdoors for an extended period of time.


Getting antioxidants from foods can be beneficial to individuals who are prone to developing polymorphous light eruption. Fish that contains omega 3 fatty acids, tomato sauce or paste (for the lycopene) and eggs are great choices.

Photo therapy

Photo therapy is one of the preventative measures that doctors use with people who already have experienced many symptoms and signs of polymorphous light eruption. This is conducted by exposing the patient’s skin to UVA or UVB light in small doses. This works to make the person’s skin less sensitive to light, as it is providing exposure in a controlled way.

Psoralen plus ultraviolet A is a kind of light therapy which combines the medicine psoralen with UVA light. It serves to make one’s skin less sensitive to the light. Some of the short-term side effects of undergoing the therapy are headaches, itching and nausea.

Last Reviewed:
September 21, 2016
Last Updated:
January 09, 2018