Polymorphous Light Eruption

Diagnosis

A healthcare professional can usually diagnose polymorphous light eruption after reviewing your symptoms, examining your skin, and discussing when the rash appears. In some cases, additional tests may be recommended to confirm the diagnosis or rule out other causes.

Skin biopsy
A small sample of the affected skin may be removed and examined in a laboratory. This helps identify features of polymorphous light eruption or exclude other skin conditions.

Blood tests
A blood sample may be taken to check for underlying conditions that can mimic light-induced reactions.

Phototesting
A dermatologist may expose small areas of your skin to controlled amounts of UVA and UVB light. If the rash appears or your skin reacts abnormally, it may indicate photosensitivity consistent with polymorphous light eruption or another light-related disorder.

Other light-induced conditions
Skin reactions to sunlight can be caused by several conditions, and your healthcare professional may need to rule them out for an accurate diagnosis. These may include:
• Chemical photosensitivity from medications, medicated creams, fragrances or certain plants
• Solar urticaria, a condition that causes itchy, raised welts within minutes of sun exposure
• Lupus rash, a sunlight-triggered eruption often affecting the face, neck or upper chest

More information
Skin biopsy

Treatment

Many people with polymorphous light eruption do not need treatment because the rash typically clears on its own within about 10 days. When symptoms are bothersome or severe, corticosteroid creams or short courses of corticosteroid tablets may be prescribed to reduce itching and inflammation.

Phototherapy
For individuals who experience recurring or disabling symptoms each season, phototherapy may be recommended. This treatment exposes the skin to controlled doses of UVA or UVB light over several sessions. Gradual exposure can help the skin adapt and reduce its sensitivity to sunlight, mimicking the natural increase in sun exposure that typically happens in early summer.