Every summer and autumn, many people have the experience of being bitten by mosquitoes and insects. Due to the differences in the reactivity of different organisms and insect species, can cause different local skin reactions, often manifested as the exposed parts of the red papules, papules, part of the surface swelling and hard, patients often come to the hospital because of itching, medical called “insect bite dermatitis”. There are many insects that cause insect bite dermatitis, common mosquitoes, fleas, mites, bedbugs, etc. They can cause insect bite dermatitis both through direct bites, but also through its metabolites or secretions cause skin inflammatory reactions. So, after being bitten by mosquitoes, redness and swelling very hard should be how to deal with it? The following side to introduce you to several treatment methods. 1, topical ointment If the mosquito bite caused by allergic reactions are mild, can be used externally heavy tincture of detoxification or aloesong and some glucocorticoid ointment. 2, topical ointment plus oral medication If the mosquito bite caused by allergic reactions are heavy, manifesting as a large area of distribution of pemphigus-like papules, maculopapular rash, can be in the external anti-inflammatory anti-itch cream at the same time, oral appropriate amount of antihistamines, such as cetirizine, loratadine, paracetamol tablets, etc., if necessary, to the regular hospital dermatology consultation. Pregnant women and younger children are prone to adverse drug reactions after taking oral antihistamines, so they should be under the guidance of a doctor for topical medications, and should not use them at their own discretion.