What should you know about sun allergy rash itchy?

Polymorphic light eruption often causes itch, redness, raised spots, or small blisters after ultraviolet exposure. The rash may emerge hours or days after sunlight, which can make the trigger easy to miss. Heat rash, eczema, contact reactions, and medicine-related photosensitivity can look similar. Note where the rash started, how quickly it appeared, and whether it affects covered skin. The [Sun Sensitivity](/symptoms/sun-sensitivity/) guide can help you describe the pattern.

Move out of direct sun, use a cool damp cloth, and moisturise with a fragrance-free product. Try not to scratch, because broken skin can become infected; keep fingernails short and cover the area loosely at night if needed. Avoid hot showers, fragranced products, and exfoliation during the flare. A pharmacist may advise an anti-itch medicine when suitable. For an inflamed localised rash, a clinician may prescribe [Topical Corticosteroids](/treatments/medical-dermatology/topical-corticosteroids/).

Get medical advice if itch prevents sleep, the rash keeps returning, or the skin becomes painful, weepy, crusted, or increasingly warm. Seek urgent help for breathing difficulty, swelling of the face or mouth, faintness, extensive blistering, or rapid deterioration. Take photographs as the rash changes and bring a list of new medicines or products.

Ask whether the appearance fits polymorphic light eruption or another condition, whether any medicine or product is involved, and which treatment is safe for the affected body area. If episodes are seasonal, ask about [Narrowband UVB Phototherapy](/treatments/medical-dermatology/narrowband-uvb-phototherapy/).