Allergy after sun exposure: signs and next steps

Polymorphic light eruption, often called sun allergy, commonly presents with itchy red bumps, patches, or small blisters on skin exposed after a period with little sun. It does not mean sunlight contains an allergen.

The upper chest, arms, shoulders, or legs may be affected, while skin regularly exposed to light can be less involved. The face may be spared in some people. Burning or itching can appear before the rash is obvious.

A clinician will consider the distribution, delay after exposure, season, and recurrence. Some antibiotics, anti-inflammatory medicines, fragrances, and plant substances can make skin react to light, so recent exposures are relevant.

Move out of direct sun, cool the skin gently, and avoid scratching or breaking blisters. Use loose clothing, shade, and a broad-spectrum sunscreen that your skin tolerates. Reapply sunscreen according to its label, especially after sweating or swimming.

Do not discontinue prescribed medicine on your own. A pharmacist or doctor can check whether a medicine may increase light sensitivity. A clinician may recommend a suitable anti-inflammatory cream for a confirmed flare.

Seek emergency help for breathing difficulty, throat or tongue swelling, faintness, confusion, or a rapidly spreading reaction with severe illness. These symptoms are not typical of a simple localised sun eruption.

Book an assessment for a first severe episode, repeated flares, extensive blistering, eye involvement, fever, strong pain, or a rash that continues despite avoiding sunlight. Photographs taken early can help show the original pattern.

Ask whether the timing and distribution fit polymorphic light eruption, a medicine-related reaction, contact dermatitis, or another diagnosis. Discuss which sunscreen ingredients suit your skin and whether supervised preventive treatment is appropriate for recurrent seasonal episodes.