A lot of small pimples on the arm may be the result of perikeratosis, folliculitis, flat warts and other diseases manifested as pimples, and need to take medication, surgical treatment, and other treatments for the cause of the disease. 1. Keratosis pilaris: common symptoms include rough skin and follicular pimples at the lesions. Patients need to follow the doctor’s instructions for external use of 0.1% retinoic acid cream, tazarotene gel, 10-20% urea cream, 3-5% salicylic acid ointment and other drugs to dissolve keratin, or follow the doctor’s instructions for oral intake of vitamin A or vitamin E and other drugs. If medication is ineffective, laser treatment can be taken. 2. Folliculitis: Typical symptoms are the presence of red papules on the hair follicles, which may be itchy and painful. For bacterial infections, topical antibiotics such as clindamycin gel and fusidic acid cream should be prescribed, and for fungal infections, drugs such as econazole cream and terbinafine cream should be prescribed. Oral medication is required for severe symptoms. If the folliculitis develops into boils or carbuncles, incision and drainage is required. In addition, you can also take the far infrared ray irradiation way to assist in the treatment. 3. Flat warts: the main symptom is the appearance of flat papules on the skin lesions, which may be accompanied by itching. Patients need to follow the doctor’s instructions to use salicylic acid, as well as interferon gel, 5% imiquimod cream and other antiviral drugs, some patients need to follow the doctor’s instructions to apply cimetidine, levamisole and other immunomodulators. Surgical excision, freezing, photodynamic and other physical treatments are also available. It is recommended that patients with a lot of small acne on the arm go to the hospital to find out the cause and follow the doctor’s instructions for treatment.