Urticaria is very troublesome for parents and children because it is accompanied by itching. In particular, many allergens, food, products, infections, inhalants, contact and other inducing factors are difficult to avoid, so urticaria often occurs. Why do the above factors cause urticaria? This should start with the pathogenesis of urticaria. The pathogenesis of urticaria is as follows: Most urticaria is caused by allergic mechanism. Allergens in food (mostly foreign proteins) stimulate the human body, causing the human body to produce specific antibody IgE (immunoglobulin E), which is attached to mast cells or basophils in the body. When eating this food again, IgE antibody will combine with allergens in the food, thus making mast cells and basophils release histamine. Histamine also acts on blood vessels, dilating blood vessels and increasing permeability, so a large amount of protein and liquid seep into skin tissue, resulting in urticaria. This is a type I allergic reaction. Many urticaria belong to this mechanism. Common ones are protein, urticaria caused by animals such as mutton, fish, shrimp, shells, crabs, milk and eggs, and plants such as strawberries, tomatoes and garlic. In addition to the common type I allergic reactions, there are also types II, III and IV. Such as urticaria caused by blood transfusion, raising antiserum, globulin and albumin, belong to type ⅲ allergic reaction. Ten causes of allergic urticaria pollen: In the season of pollen transmission, tiny pollen particles will be scattered in the air and fly around with the flow of air, and some of them will be inhaled by people and absorbed by the skin. Dust: dust chronic urticaria is a chronic urticaria reaction of microorganisms living in dust, and it is a common chronic urticaria. Dust chronic urticaria includes cotton fiber, fur and various fibers, animal fur and so on. Cosmetics: Typical cosmetic chronic urticaria is essence chronic urticaria, and alcoholic cosmetics such as make-up water can also cause certain irritation to the skin. Others, such as biochemical preservatives, fruit acids, etc. , will cause different irritation to different skin. Food: Common foods such as seafood, mangoes and nuts can cause chronic urticaria. Products: penicillin, sulfanilamide products, etc. , may cause chronic urticaria of the skin. Age: The increase of age and the imbalance of immunity are the important causes of chronic urticaria. Pets: Domestic pets have chronic urticaria. This kind of chronic urticaria caused by pets is mainly due to the fact that the substances on cats and dogs are scattered into the air, which causes chronic urticaria after human contact. Seasonal changes: due to various environmental factors, bacterial spores and pollen scattered in the air will release a large number of compounds that the human body can contact-histamine, causing chronic urticaria. Temperature change: the temperature is hot and cold, which causes chronic urticaria in sensitive people. Unscientific external use of improved instruments, external use of hormone ointment and external use of ultraviolet radiation lead to chronic urticaria. Some causes of urticaria have nothing to do with allergens. 1, non-allergic histamine release. For example, some products (aspirin, morphine, sulfanilamide, penicillin, atropine, etc. ) and other biological, chemical and physical factors can directly act on mast cells to release histamine and cause urticaria, without allergic mechanism 2. Cholinergic urticaria. Warmth, exercise and emotional excitement can make cholinergic nerve endings of autonomic nervous system release acetylcholine. Acetylcholine can directly cause vasodilation, and also promote the release of histamine, causing urticaria. 3, direct stimulation of blood vessels can cause urticaria. Some factors can directly stimulate vasodilation and produce urticaria, such as drinking, mental stress, insomnia and products that can dilate blood vessels. 4. Genetic factors. Such as familial urticaria syndrome, delayed familial localized urticaria and hereditary angioedema. Very rare. In short, there are many reasons for urticaria, and its mechanisms are allergic and non-allergic. Label: urticaria, measles