This causes a reaction within a few seconds or minutes of exposure to sunlight, of urticaria (or ‘hives’) ----itchy swollen often red patches. The reaction settles down within a few minutes or generally an hour or two once one gets out of the sun. Some patients do get this condition very badly, sometimes winter and summer, and it can be disabling. Phototesting is needed to confirm the diagnosis and find out which types of light are causing the reaction. An extra complication is that, unlike most light sensitive skin diseases which are caused by ultraviolet light, solar urticaria is often caused by ultraviolet but can be caused by visible non-ultraviolet light, for which conventional sunblocks will not be effective. Antihistamines sometimes in high dose , help many patients, and a variety of other treatments can be helpful. Because of potential treatment complications, this condition is generally only treated in specialist centres with experience of patients with this disease.