After being bitten by a bug, redness, swelling, pain and pustules can be treated with local medication, oral medication, incision and drainage, and so on. 1. local medication: if the pus is not particularly large, itching is not particularly serious, you can use glycerine lotion, compound camphor cream, etc., at the same time, you can use antibiotic drugs, such as clindamycin gel, mupirocin ointment and other drugs. 2. Oral medication: If the effect of local medication is not obvious or the itching is more serious, you can also take oral medication under the guidance of a doctor, mainly oral antihistamines, such as cetirizine tablets or loratadine tablets. If accompanied by systemic symptoms such as fever, also need oral antibiotics such as amoxicillin capsules. 3. Incision and drainage: the pustule is relatively large, more pus, can also go to the hospital for incision and drainage, after the incision and drainage, need to apply antibiotic drugs to prevent infection, such as erythromycin ointment. If you are bitten by a bug with redness, swelling and pus should pay attention to, do not scratch the local, usually in life should pay attention to personal hygiene and environmental hygiene, try to minimize the situation of bug bites.