A. What causes the phenomenon of insect bite reaction? The disease is related to insect bites, such as bedbugs, fleas, lice, mites, mosquitoes, etc. After the arthropod bites the skin, its saliva and other secretions lead to skin irritation or allergic reactions and cause disease. Second, what are the symptoms of insect bite reaction? Insect bites can cause local reactions, papular urticaria or systemic allergic reactions. 1, local reactions caused by various substances in the insect saliva irritate the skin. It usually appears within minutes after the bite and is characterized by localized pruritic edematous erythema, which usually fades within a few hours. 2.Papular urticaria is a delayed allergic reaction that occurs after an insect bite, characterized clinically by wind-blown lesions with intense itching. It is mainly seen in children aged 2 to 10 years old, and the rash is usually found on exposed areas such as the extremities, clustered or scattered. The typical rash is a fusiform red papule of green bean to peanut size, often with small blisters at the top, or tense blisters. The rash is often accompanied by intense itching, which interferes with sleep. Scratching can lead to secondary infection. The rash can subside in 1 to 2 weeks, leaving temporary hyperpigmentation, but new rashes often occur one after another to prolong the course of the disease, and the old and new rashes often exist at the same time. 3, systemic allergic reactions A few patients (especially those with combined mastocytosis) can have severe systemic allergic reactions after being bitten by insects, manifesting as generalized edematous erythema or wind mass, laryngeal edema and anaphylaxis. How to treat insect bite reaction? 1, local treatment Immediately after the discovery of insect bites with soap and water to clean the skin of the bite, edema erythema to boric acid lotion or magnesium sulfate cold wet compress, external application of 1% of furnace glycerin menthol lotion; papular urticaria to strong glucocorticoid cream for external use. 2.Systematic treatment According to the rash situation and the degree of itching, give oral antihistamines, such as cetirizine, loratadine, cycloheximide, etc.. Short-term systemic application of glucocorticoids can be used for those with significant edema. Those with systemic allergic reactions should be given subcutaneous or intramuscular injection of epinephrine immediately and systemic application of glucocorticoids at the same time.