There are many causes of the disease, including food, medications, stress, climate change, etc. Many patients have difficulty identifying the exact cause. About 3/4 of patients cannot find the cause, especially in chronic urticaria. Common causes include: food and food additives; inhalants; infections; medications; physical factors such as mechanical stimulation, heat and cold, sunlight, etc.; insect bites; psychological factors and endocrine changes; genetics, etc. The common causes of urticaria are as follows: food is most common with fish, shrimp, crab and eggs. Secondly, certain spices and condiments can also cause. Drugs such as penicillin, sulfonamides, dysentery, serum vaccines, etc., often trigger urticaria through the immune mechanism. Drugs such as aspirin, morphine, atropine and vitamin B1 are histamine-releasing substances that can directly cause histamine release from mast cells to cause urticaria. Infections: including viruses such as epizootic virus, hepatitis virus, bacteria such as golden grape, fungi and parasites such as roundworms. Animal and plant factors, such as insect bites or inhalation of pollen, feathers, dander, etc. Physical factors, such as heat and cold, sunlight, friction and pressure can be caused. In addition, gastrointestinal diseases, metabolic disorders, endocrine disorders and psychological factors can also cause urticaria.