The baby does not know what bites appear red and swollen, consider the possibility of insect bite dermatitis, you can use soapy water, topical medications, oral medications and other relief. 1. Soap and water: if the baby was bitten only slightly red and swollen, you can use alkaline soap and water to scrub the affected area. 2. Topical medications: baby skin is relatively tender, the skin is more prone to redness and swelling after being bitten, you can first apply a cold compress. If it can not be relieved, you can use glycerine lotion, glucocorticosteroids such as hydrocortisone cream, Dinaid cream according to the doctor’s instructions. 3. Oral medication: For allergic babies, severe swelling and itching may occur after being bitten, at this time you can follow the doctor’s instructions to take cetirizine hydrochloride drops, loratadine granules and other antihistamines. After the baby did not know what was bitten and red and swollen, it is recommended to take the baby to the doctor in a timely manner to carry out relevant examinations, and then give targeted treatment, note that the above drugs need to be used under the guidance of a doctor.