When you have hives, especially chronic hives, finding the cause becomes the first task of the patient and the doctor. However, unfortunately, due to various reasons, only a small number of patients have been able to find the cause and get to the root of the problem, while as many as 3/4 of patients are still on the road to finding the cause. Nevertheless, the following aspects of the cause of the disease still need to be investigated one by one. 1, food and food additives. Animal food mainly includes fish, shrimp, eggs, milk, crab, etc., while plant food includes bamboo shoots, eggplant, spinach, apples, plums, peaches, etc. Food additives such as coloring, preservatives, yeast, salicylic acid, etc. 2.Inhalation. Animal dander, pollen, mites, fungal spores, dust, formaldehyde, acrolein, pyrethroid insecticides, etc. 3, infection. Including bacterial infections such as tonsillitis, boils, respiratory infections, cholecystitis, pancreatitis, sinusitis, appendicitis stomach H. pylori infection; viral infections such as viral hepatitis, coxsackievirus infection, infectious mononucleosis, etc.; parasitic infections such as Plasmodium, roundworms, hookworms, pinworms, amoeba lysis, filarial worms, schistosomes, scabies, etc. 4.Drugs. Penicillin, sulfonamides, serums, vaccines, etc. often cause immune urticaria; aspirin and other non-steroidal anti-inflammatory drugs, polymyxin, cartridge poisoning base, morphine, codeine, etc. often cause the release of histamine, directly leading to urticaria. 5, physical factors. Such as cold, heat, sunlight exposure, mechanical vibration, pressure, etc. 6, insect bites or insect body surface substances. Such as bees, wasps, mulberry caterpillars, spiders, moths, etc. 7, mental factors and endocrine changes. Such as mental tension, shyness, emotional excitement; menstruation, menopause, pregnancy, etc. 8.Medical diseases. Systemic lupus erythematosus, lymphoma and other malignant tumors, hyperthyroidism, rheumatism and rheumatoid, liver disease, ulcer disease, diabetes, etc. 9, genetic factors.