Sun urticaria: what to know

The rash may appear on uncovered areas while skin protected by clothing remains unaffected. It can feel intensely itchy, burn, or swell, and it may fade after the light exposure ends. The reaction can involve visible light or ultraviolet light, so a window or thin fabric does not always provide complete protection. Sun urticaria is different from delayed sunburn and from a rash caused by a product reacting with sunlight. A dermatologist can use the history and, when needed, controlled light testing to clarify the trigger.

Move out of direct sunlight when symptoms begin, cover the skin with closely woven clothing, and use shade and a broad-spectrum sunscreen. Keep a record of the light exposure, medicines, products, and time to symptoms. A clinician may discuss Antihistamine Treatment; more persistent or extensive disease may need specialist-directed options, including Oral Corticosteroid Treatment in selected circumstances. Do not start steroid tablets without medical advice.

Call emergency services for trouble breathing, throat or tongue swelling, faintness, wheezing, or rapidly worsening symptoms, because a severe allergic-type reaction needs immediate treatment. Seek prompt medical review for widespread hives, marked skin swelling, dizziness, or repeated episodes. Swelling around the eyes or lips can be a form of angioedema and should not be ignored.

Does the timing fit sun urticaria or another light-sensitive rash? Which wavelengths or medicines might be involved? Should I use an antihistamine, and which one is suitable for me? What emergency symptoms should my household recognise?