Urticaria is the most common clinical allergic skin disease, occurring at least once in the lifetime of 15-20% of people. According to the course of the disease, there are two types of urticaria: acute urticaria usually heals within days or even hours after treatment, while chronic urticaria recurs for more than 3 months or even decades. The typical lesion is a red or pale white bruise of varying size, round, oval or irregular in shape, isolated, scattered or fused into patches, usually lasting no more than 24 hours, but new bruises occur one after another, with intense itching of the lesions. Acute urticaria can be accompanied by panic, irritability, nausea, vomiting, even lower blood pressure and other allergic body gram-like symptoms, part of the gastrointestinal mucous membrane edema abdominal pain, when severe, rather like acute abdomen, and can appear diarrhea, if the trachea, larynx mucosa involved, respiratory distress, or even asphyxia. Chronic urticaria generally has mild systemic symptoms, sometimes more and sometimes less, with recurrent attacks, often for months or years. There may be regularity, such as aggravation in the morning or before bedtime or seasonal attacks. Most patients cannot find the cause themselves. Most patients cannot find the cause themselves. Most patients cannot find the cause themselves. The clinical classification of urticaria includes: 1. Skin scratching: also known as artificial urticaria. It is caused by scratching or scratching the skin with a hard object for 5-15 minutes, and then a striated elevation along the scratch with itching, which soon subsides; 2. Cold urticaria: familial and acquired, the latter being more common. After contact with cold wind, cold water or cold objects, the exposed or contact areas produce wind or patchy edema; 3, cholinergic urticaria: mostly seen in young people. Due to exercise, heat, emotional stress, eating hot drinks or ethanol drinks to make the deep body temperature rise, prompting the action of acetylcholine on mast cells and occur. It is a 2-3mm diameter, surrounded by a red halo, about 1-2mm, and can subside within half an hour to an hour; 4, solar urticaria: less common, caused by medium-wave and long-wave ultraviolet light or visible light, the skin occurs in exposed areas, itching and stinging sensation; 5, compressional urticaria: about 4-6 hours after the skin pressure, local swelling, involving the dermis and subcutaneous tissue, lasting 8-12 hours 6, angioedema: is a kind of limited edema occurring in the subcutaneous tissue more lax parts and mucous membranes, divided into hereditary and acquired, the latter is common, often accompanied by other genetic allergic diseases. It occurs mainly on the eyelids, lips, mouth, external genitalia, and hands and feet. The lesions are sudden, limited swelling with indistinct borders, normal or light red skin color, and shiny surface, which can gradually subside in 1-3 days. If it occurs in the laryngeal mucosa, it can cause respiratory distress and even death by asphyxiation.