solar urticaria

Solar urticaria is a form of hives triggered by exposure to sunlight. It is a hypersensitive skin reaction characterized by itchy, raised wheals and plaques that are redder or paler than the surrounding skin. This reaction is caused by the release of histamine from mast cells in the skin, which increases capillary permeability and leads to swelling. While common causes of urticaria include allergies to foods or drugs, physical factors like sunlight can also produce the response. Treatment typically involves avoiding the trigger and may include antihistamines.12