A lot of small red dots on the arm may be caused by diseases such as cherry angioma, allergic purpura, perikeratosis, etc. Depending on the disease, different ways to improve are taken. 1. Cherry hemangioma: cherry hemangioma may cause a lot of small red dots on the arm, patients can take laser treatment to destroy the hemangioma tissue through laser. Microwave and electrocoagulation can also be treated to help improve the symptoms of the lesions. 2. Anaphylactic purpura: a lot of small red dots on the arm may be caused by anaphylactic purpura, avoid contact with irritants or allergens in daily life, and eat a light diet. You can also take drugs such as Troxerutin, which has the effect of improving vascular permeability. Serious patients can take prednisone, methylprednisolone and other glucocorticoids as prescribed by the doctor. 3. Keratosis Pilaris: If there are a lot of small red dots on the arm caused by keratosis pilaris, you need to pay attention to sun protection and moisturize the skin. Patients can follow the doctor’s prescription salicylic acid ointment, urea cream and other drugs, can soften the keratin. There are many reasons that lead to a lot of small red dots on the arm, it is recommended that patients go to the hospital and follow the doctor’s instructions for medication.