In the clinic, patients often ask me: I’ve been paying attention to what I eat, but why is my hives still bad? Or, why do I still get hives when I don’t eat anything? Is hives caused by a poor diet alone? To answer this question, we must first understand the cause of hives. Urticaria is an allergic disease, i.e. an allergic disease. Its onset is associated with a variety of factors. Such as: food, drugs, infections, physical and chemical, animal and plant factors, neurological factors, systemic diseases and genetic factors. It can be divided into two categories: immune and non-immune. Immune-related urticaria is mainly caused by type I allergic reactions, while a few are caused by type II or type III allergic reactions; non-immune mechanisms of urticaria are mostly triggered by external factors. These include: certain drugs, food, physical factors, chemical substances, enzymes and tissue damage can act directly on mast cells and basophils, causing them to release histamine and other vasoactive substances, thus causing urticaria. It is thus clear that urticaria is not singularly caused by a poor diet. Of course, food is a major factor in inducing urticaria, of which, mostly fish, shrimp, crab and eggs are the most common, followed by certain meats and certain plant foods such as strawberries, cocoa, tomatoes or spices like garlic. Some food-induced urticaria are allergic in nature, but some unfresh foods decay and break down into peptides, alkaline peptides are histamine releasers, and protein foods are absorbed in the form of peptones or peptides before they are thoroughly digested, which can cause urticaria. It is called peptone-type urticaria. Also, not to be overlooked and now increasingly common are drug-induced urticaria. Common ones are penicillin, serum preparations, various vaccines, sulfa, etc. Aspirin, morphine, codeine, quinine. Various infections can also induce urticaria; it includes viruses, bacteria, fungi, parasites, etc. The most common are viruses and Staphylococcus aureus, which cause upper respiratory tract infections, followed by hepatitis virus. The relationship between chronic infectious lesions, such as sinusitis, tonsillitis, and chronic otitis media, and the development of urticaria is not easy to determine simply and can only be confirmed by therapeutic trials. Therefore, some patients with urticaria accompanied by abnormal body temperature should pay attention to the blood picture and available anti-inflammatory treatment. In addition, physical factors such as cold, heat, sunlight, friction and pressure, which we all know are physical stimuli. Animal and plant factors such as insect bites, nettle irritation or inhalation of animal dander, feathers and smallpox powder. Mental factors such as mental stress can cause acetylcholine release. Visceral and systemic diseases such as rheumatic fever, rheumatoid arthritis, systemic lupus erythematosus, malignant tumors, infectious mononucleosis, metabolic disorders, endocrine disorders, etc., can also be the cause of urticaria, especially chronic urticaria. Because of the many causes of urticaria, it is difficult to distinguish clearly in the clinic, and sometimes it is difficult to avoid, so the treatment is more difficult and the course of treatment is longer.