The general term for hives is urticaria, the causes of which are complex and varied, and are commonly found in drugs, food, insect bites, physical factors and so on. 1. Drug factors: many drugs can cause allergic reactions or directly stimulate mast cells to release mediators, and the occurrence of hives such as drug dermatitis. 2. Food factors: some people eat seafood and some high-protein foods can appear after the rash, manifested as peptone urticaria, papular urticaria and so on. 3. Insect bites: some mosquito bites in summer can cause allergic reaction or toxin reaction which can lead to hives. 4. Physical factors: cold stimulation and strong sunlight can cause hives, cold urticaria and solar urticaria are common. If you have the symptoms of hives, you should go to the hospital as soon as possible, and the doctor will make individualized diagnosis and treatment plan according to the specific condition, so as not to delay the condition.