Bitten by small black bugs itchy, belonging to the insect bite dermatitis, can be adjusted through general treatment, local medication, systemic medication and other measures. 1. General treatment: first of all, keep the biting part of the skin clean and hygienic, do not use hot water to scald, use cold water to rinse, can use ice, cool towels, cold compress, and avoid excessive squeezing and scratching the skin lesions. 2. Topical medication: glucocorticoid ointment can be used externally for treatment, such as hydrocortisone ointment, tretinoin cream and so on. 3. Systemic medication: If the swelling and itching are severe, antihistamines (loratadine, chlorpheniramine) and glucocorticosteroids (prednisone, dexamethasone) can be used. If the above symptoms occur, it is recommended that patients go to the hospital for examination first, and then follow the doctor’s instructions for medication after clarifying the cause of the disease.