Urticaria, commonly known as “rubella”, is a limited edematous reaction due to dilation and increased permeability of small blood vessels in the skin and mucous membranes, which usually resolves within 2-24 hours, but new rashes occur repeatedly. It is prolonged for several days to several months. Between 15-20% of people have at least one episode of urticaria in their lifetime. The etiology of urticaria is complex and the cause cannot be found in about 3/4 of patients, especially in chronic urticaria. 1. Food and food additives Mainly animal protein foods such as fish, shrimp, crab, meat, eggs (or spoiled); plant foods such as eggplant, bamboo shoots, spinach, apples and plums and other vegetables and fruits. Natural or synthetic substances in food such as coloring, condiments, preservatives, yeast, salicylic acid, citric acid, azo-like tetrazolium and benzoic acid derivatives, etc. 2, inhalants such as pollen, animal dander, feathers, fungal spores, dust, formaldehyde, acrolein, castor powder, pyrethrum, gas and other inhalation can occur urticaria, and these patients are often accompanied by respiratory symptoms. 3, infection Various acute and chronic infection factors can cause this disease, including: ① bacterial infection, such as acute tonsillitis, pharyngitis, impetigo, boils, cholecystitis, appendicitis, pancreatitis, sinusitis, etc.. It has been reported that H. pylori can indirectly cause the production of autoantibodies and have a relationship with chronic urticaria. ② Viruses, such as the prodromal phase or jaundice phase of viral hepatitis are common. Coxsackie virus infection and infectious mononucleosis are directly related to the development of urticaria. Parasites, such as Plasmodium, Ascaris, hookworms, pinworms, amoeba, trichinella, Giardia lamblia and other intestinal parasites, as well as schistosomes, filarial worms, cysticercus, etc. 4, drugs Many drugs are often prone to cause this disease, penicillin, sulfonamide, serum, vaccines, etc.. It is usually an immune response. However, some drugs are themselves histamine releasing agents, such as aspirin and other NSAIDs, morphine, codeine, cylindrotoxin, polymyxin, etc. 5, physical factors such as mechanical stimulation, heat and cold, sunlight, etc. 6, insect bites Bees, wasps and other insect bites caused by the metaplasia, wind mass is a prominent symptom. Caterpillars, beetles, bags of spiders and moths, etc. hair scales into the skin can also occur. 7, mental factors and endocrine changes such as mental tension, emotional impulsiveness, etc.. Menstruation, menopause, pregnancy, etc. can also be affected by this disease. 8. Internal diseases 7-9% of patients with SLE have urticaria. In addition, lymphoma, carcinoma, hyperthyroidism, rheumatism and rheumatoid arthritis, hyperlipidemia and chronic lesions such as oral, dental and gum diseases, gastritis, enteritis (allergic colitis, ulcerative colitis), cholecystitis, nephritis, liver disease, ulcerative disease, diabetes, etc. 9, genetic factors Urticaria related to genetics are hereditary familial urticaria syndrome, familial cold urticaria, delayed familial restrictive heat urticaria, erythropoietic protoporphyria.