Skin eruptions after mosquito bites are associated with localized allergic reactions. When a mosquito lands on human skin, it pricks the skin through its mouthparts and injects saliva into the human skin. Mosquito saliva contains anesthetic and formic acid components. Formic acid irritates human skin and causes human skin cells to produce histamine. Histamine causes an allergic reaction with skin edema and the appearance of what looks like a pouch. The time it takes for the bag to fade after a mosquito bite varies from person to person. For people who are not allergic to mosquito venom, there will only be a small red spot on the area, which can disappear within three to seven days. However, if the itching is obvious, glucocorticoid ointment such as mometasone furoate cream can be applied under the guidance of a doctor to effectively relieve the itching and promote fading. If necessary, take oral anti-allergy drugs, such as loratadine. After being bitten by mosquitoes, timely symptomatic treatment.