Urticaria is a restrictive edematous reaction due to reactive dilation and increased permeability of small blood vessels in the skin and mucous membranes, which mainly manifests as itchy red or pale lesions with clear margins – wind clusters. Etiology The etiology of urticaria is complex, and the exact cause cannot be found in most patients. Common etiologies are as follows. 1. Food Fish, shrimp, crab and eggs are the most common, followed by certain meats and certain plant foods such as strawberries, cocoa, tomatoes or spices such as garlic. Some food-induced urticaria can belong to the allergic reaction. However, there are not fresh food decay decomposition into peptides, alkaline peptides are histamine release, protein food before complete digestion, in the form of peptones or peptides are absorbed, can cause urticaria. 2, drugs Many drugs are prone to cause the body’s metamorphosis leading to the disease, common are penicillin, serum preparations, various vaccines, dysentery, sulfonamide, etc.. Some drugs are histamine releasing substances, such as aspirin, morphine, codeine, quinine, hydrazinebendazole, etc. 3, infection including viruses, bacteria, fungi, parasites, etc.. The most common are viruses and Staphylococcus aureus, which cause upper sensation, followed by hepatitis virus. Chronic infectious lesions, such as sinusitis, tonsillitis, chronic otitis media and the relationship between the onset of urticaria, is not easy to determine simply, and must be confirmed by treatment trials. 4, physical factors such as cold, heat, sunlight, friction and pressure and other physical stimuli. 5, animal and plant factors such as insect bites, nettle stimulation or inhalation of animal dander, feathers and pollen, etc. 6, mental factors such as mental stress can cause the release of acetylcholine. 7, visceral and systemic diseases such as rheumatic fever, rheumatoid arthritis, systemic lupus erythematosus, malignant tumors, infectious mononucleosis, metabolic disorders, endocrine disorders, etc., can be the cause of urticaria, especially chronic urticaria. Clinical manifestations It is a common disease that occurs at least once in the lifetime of 15-20% of people. According to the course of the disease, it is divided into two categories: acute and chronic, the former can be cured in a short period of time; the latter is recurrent for months to years. Acute urticaria is often acute, with sudden itching of the skin and the appearance of red bumps of varying sizes, round, oval or irregular in shape. They are isolated or scattered at the beginning, and gradually expand and fuse into patches. When the serous exudation from the microvasculature is rapid, it compresses the wall of the canal, and the pale skin becomes uneven and orange peel-like. Within a few hours, the edema decreases and the puffiness becomes erythematous and gradually disappears. The duration of the wind masses usually does not exceed 24 hours, but new wind masses occur one after another. In severe cases, anaphylactic shock-like symptoms such as panic, irritability, nausea, vomiting and even lowered blood pressure may be associated with the disease. Some of them may have abdominal pain due to gastrointestinal mucosal edema, which may resemble acute abdomen when it is severe, or diarrhea, which may occur with shortness of breath and mucousy stools. When the trachea and larynx mucosa are involved, respiratory distress and even asphyxia may occur. If there are symptoms of systemic toxicity such as high fever, chills and rapid pulse rate, we should be especially alert to the possibility of serious infections such as sepsis. Routine blood tests have elevated eosinophils. In case of severe Staphylococcus aureus infection, the total white blood cell count is often increased or the percentage of neutrophils is increased with a normal cell count, or there are also neutrophil granules. Chronic urticaria is generally milder, with more and less wind clusters, recurring, often for months or years. Some have a temporal nature, such as morning or bedtime aggravation, while others have no certain pattern. Most patients cannot find the cause of the disease. Third, special types of urticaria 1, skin scratching syndrome also known as artificial urticaria. After scratching or scratching the skin with a blunt instrument, striated elevation along the scratch occurs, accompanied by itching, which soon subsides. It can occur alone or in combination with urticaria. 2, cold urticaria can be divided into two types: a familial, autosomal dominant inheritance, more rare, shortly after birth or early onset, repeated throughout life. The other is acquired, more common. After exposure to cold wind, cold water or cold objects, the exposed or exposed parts of the body produce wind or patchy edema. In severe cases, there may be hand numbness, lip numbness, chest tightness, palpitations, abdominal pain, diarrhea, syncope and even shock. Sometimes eating cold drinks can cause edema of the mouth and throat. Passive transfer test may be positive, which may be related to IgE. Ice can induce localized wind clumps. Cold urticaria can be one of the symptoms of certain diseases, such as cold globulinemia, paroxysmal cold hemoglobinuria, cold fibrinogenemia, cold hemolysis, etc. 3, cholinergic urticaria Most often 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. The rash appears a few minutes after irritation, with a diameter of 2 mm ~ 3 mm, surrounded by a red halo, about 1 cm ~ 2 cm. It often spreads on the upper trunk and upper limbs, does not fuse with each other, and can subside within half an hour to an hour, with severe itching. Sometimes there is only severe itching without a rash. It is occasionally accompanied by systemic reactions to acetylcholine, such as salivation, headache, slow pulse, narrow pupils, and spasmodic abdominal pain, diarrhea, and croup. Dizziness may be severe enough to cause syncope. The course of the disease usually improves after several years. 1:5000 acetylcholine for skin test or scratch test, can be injected at the site of the wind, around the appearance of small star-shaped wind clusters. 4, solar urticaria Less common, caused by medium-wave and long-wave ultraviolet light or visible light. The most sensitive to ultraviolet light with wavelength of about 300nm. Passive transfer test can be positive for those who are allergic to 285nm ~320nm ultraviolet light. Itchy and prickly sensation occurs on the exposed skin, and can sometimes be triggered by sunlight through glass. In severe cases, there are systemic reactions such as chills, weakness, syncope, crampy abdominal pain, etc. 5.Pressure urticaria Local swelling occurs about 4~6 hours after the skin is pressurized, involving the dermis and subcutaneous tissue, and lasts 8~12 hours to subside. It is common on the bottom of the feet after walking and on the skin of the buttocks after being compressed. The mechanism is unknown and may be similar to skin scratching. 6, angioedema is a kind of limited edema occurring in the subcutaneous tissue more lax parts or mucous membrane, divided into two kinds of acquired and hereditary, the latter rare. Acquired angioedema, often accompanied by other genetic allergic diseases. It occurs mainly in areas with lax tissue, such as eyelids, lips, external genitalia, hands and feet. It is mostly solitary, occasionally occurring in more than two locations. The damage is a sudden, limited swelling involving subcutaneous tissue with indistinct borders. The skin color is normal or light red, and the surface is bright and elastic to the touch. The swelling may fade gradually in 1 to 3 days, or it may recur in the same area. If it occurs in the laryngeal mucosa, it may cause respiratory distress and even death by asphyxiation.