Bitten by mosquitoes and scratched to appear red and swollen can be used iodophor, topical medicine as well as oral medication methods. 1. Povidone-iodine: Povidone-iodine should be applied to the local area immediately to sterilize and prevent infection. 2. Topical medication: when localized redness and swelling occurs, you can apply light to moderate glucocorticoid ointment, such as dexamethasone ointment, halomethasone cream and so on. 3. Oral medication: when the redness and swelling is serious, you can use ice packs to reduce the swelling, and if there is a red rash on the body, you can take antihistamines, such as loratadine tablets, cetirizine tablets and so on. If there is redness and swelling after being scratched by mosquito bites, it is recommended to use medication under the guidance of a doctor, and not blindly, so as not to aggravate the condition.