Chronic urticaria is called chronic urticaria when lesions recur for more than six weeks and at least two episodes per week. The causes of the onset are: 1, food: animal proteins, such as fish, shrimp, shellfish, milk, eggs and plants; certain food additives can lead. 2, infection: various viral infections, such as viral upper respiratory tract infections, hepatitis; bacterial infections, such as Staphylococcus aureus, Candida infections are fungal infections, including superficial fungal infections and parasitic infections. 3, drugs: common, such as penicillin, serum preparations 4, respiratory inhalants and skin contacts, common inhalants are pollen, animal dander, dust, fungal spores, skin contacts are saliva, semen, toxic caterpillar stimulation. 5, physical factors: such as heat and cold, sunlight, friction, pressure, etc. 6, mental and endocrine factors: such as mood swings, tension, depression, etc. 7, systemic diseases “such as Rheumatic fever, systemic lupus erythematosus, malignant tumors, autoimmune thyroiditis, etc. 8, other factors: some chronic urticaria may have abnormalities in coagulation and immune function.