There are small red bags on the arm to consider the insect bite dermatitis, urticaria, folliculitis and other diseases caused by the need to take general treatment, medication and other ways to improve. 1. insect bite dermatitis: small red bags on the arm is generally insect bite dermatitis, can be applied locally glycerine lotion to stop the itching, you can also follow the doctor’s instructions for topical glucocorticosteroids, such as dexamethasone, hydrocortisone, etc., with anti-inflammatory, anti-allergic effect. 2. Urticaria: If you suffer from urticaria, it will lead to small red packets on the arms, accompanied by obvious itching. You can take antihistamines such as loratadine and cetirizine as prescribed by the doctor, which have the effect of anti-allergy and anti-itching. 3. Folliculitis: manifested as red papules centered on hair follicles, can occur in the arm. Patients should pay attention to hygiene, keep local clean, avoid scratching. You can follow the doctor’s instructions for topical antibiotic treatment, such as mupirocin, erythromycin and other drugs. There are more reasons for small red packets on the arm, it is recommended that patients seek medical examination to clarify the cause of the disease, and cooperate with the doctor to standardize the treatment.