The etiology of urticaria in children is not significantly different from the etiology of the disease in other populations and may be related to food, infections, medications, volatiles in the air, and psychological factors. Urticaria is a multi-causal allergic disease, most patients can not find a specific cause, the common ones are: 1. Food. Animal proteins such as fish, shrimp, crab and seafood, or certain additives, such as snacks are common causes, and newly added foods from 1 hour to 3 days after eating should be considered. 2, infection. Including viral infections, bacterial infections are present, a small percentage of which may or may not have fever. For patients who respond poorly to conventional anti-allergy treatment, it is important to rule out the possibility of this trigger. 3, Drugs. The drugs that cause urticarial rash are mainly penicillin and vaccines. 4, volatiles. For example, airborne pollen, dust, household dust mites, formaldehyde, etc. 5, mental factors. For example, mood swings. In addition, cold and heat stimulation, sunlight, friction, gastritis, hyperthyroidism and other chronic diseases can also lead to urticaria. The causes of urticaria are complex and difficult to find. For occasional urticaria, a brief recollection of life experiences before the onset of the disease can be used to rule out the possibility of food, drugs, or volatiles, and if so, active avoidance and oral loratadine syrup is sufficient. When there is no obvious trigger, allergen testing can be perfected.