The common causes of urticaria include food factors, infectious factors, drug factors, physical factors, mental factors, chronic diseases and so on. 1. Food factors: food and food additives can induce urticaria, such as fish, shrimp, crab, milk and eggs. 2. Infectious factors: for example, chronic hepatitis, viral infections, fungal infections, parasitic infections, etc. may also cause urticaria. 3. Drug factors: for example, the use of certain antibiotics, penicillin drugs, sulfonamides, or serum products, various vaccines, etc., may also induce urticaria. 4. Physical factors: temperature changes in the external environment, sunlight exposure, friction, extrusion, etc. 5. Chronic diseases: endocrine disorders, malignant tumors, systemic lupus erythematosus, ulcerative colitis, etc., may also induce urticaria. Frequent urticaria should be timely medical treatment, under the guidance of the doctor to carry out the appropriate examination, follow the doctor’s instructions for treatment.