Chronic urticaria can be found through diet, medication and inhalants. 1. Food: If you eat fish, shrimp, milk, eggs, mushrooms, strawberries, tomatoes and other foods that are not thoroughly digested after eating, they may be absorbed by the body in the form of peptones or polypeptides, which may then cause symptoms of chronic urticaria. 2. Drugs: The recent use of penicillin, furazolidone, serum products and other antigenic drugs, or the use of aspirin enteric-coated tablets, ibuprofen extended-release capsules and other non-steroidal anti-inflammatory drugs may also lead to the symptoms of chronic urticaria. 3. Inhalants: When pollen, animal hair, dust, chemicals and other components of the polluted environment are inhaled into the body, it may cause the body to develop symptoms of chronic urticaria. The causes of chronic urticaria are more, should go to the hospital in time for examination and diagnosis, as soon as possible for targeted treatment.