As the climate warms up, the number of patients suffering from papular urticaria has increased dramatically, so we would like to share some general knowledge about this today. Papular urticaria is also known as urticarial moss and infantile moss. It is a common allergic skin disease in infants and children, but adults can also suffer from this disease. Often several people in the same family develop it at the same time. It occurs more often in spring and autumn. The disease is a disease named after its symptomatic features, and in fact the disease is known as insect bite dermatitis. The clinical features are scattered, slightly hard papules with small blisters on the tip. It is surrounded by a fusiform redness and is self-induced itching. Etiology The majority of cases are related to insect bites such as mosquitoes, bedbugs, fleas, lice, mites, midges, and other bites that cause allergic reactions. Individual qualities react differently to insect bites. Insect bites inject saliva into the skin and cause the disease in children who are allergic to these substances. This is a delayed allergic reaction, sensitization takes about 10 days, then the bite will contribute to the rash. Manifestations The lesions are mostly on the trunk and the extremities. They are clustered or scattered. They are slightly fusiform red lesions of green bean to peanut size, some may have pseudopods, often with small blisters at the tip, and some become large hemispherical elevated tense blisters with clear content and no surrounding redness soon after occurrence. The rash is skin-colored or light red or light brown, and in some cases it is a hard, chestnut-sized papule that becomes swollen after scratching. Old and new rashes often coexist. In general, young children have significant redness and blisters, and often have severe itching that affects sleep. Scratching can cause secondary infection. The rash fades after 1 to 2 weeks, leaving temporary hyperpigmentation, but a new rash can occur one after another, making the disease prolonged. The rash is often recurrent and usually has no systemic symptoms. Local lymph nodes are not enlarged. Treatment Internal antihistamines have a good effect. Topical application of 1% peppermint glycolic lotion or 1% peppermint cream (children should pay attention to the stimulation of drugs) and glucocorticoid cream can stop itching and reduce inflammation. If there is secondary infection to be anti-infective treatment. Prevention 1, improve environmental, indoor and personal hygiene, pay attention to indoor ventilation and dryness to eliminate the breeding of insects that cause the disease; 2, indoor and outdoor insecticide can be sprayed at the residence to eliminate bedbugs, fleas, mosquitoes and other harmful arthropods.