Red rash on the arm may be eczema, peri keratosis, contact dermatitis, etc., need to be on the cause of the general treatment, drug treatment, surgical treatment. 1. For eczema, we should pay attention to the diet, avoid smoking and drinking, avoid spicy and stimulating food; can follow the doctor’s instructions orally levocetirizine and other antihistamines, topical hydrocortisone and other glucocorticosteroids. 2. For the keratosis pilaris caused by, can follow the doctor’s instructions for external use of retinoic acid cream, such as exfoliation, cyclosporine oral solution, etc. can control inflammation. 3. For contact dermatitis, oral antihistamine drugs such as loratadine and topical glucocorticoid ointment such as dexamethasone can be used as prescribed by the doctor. It is recommended that people with red rashes on the arm go to a regular hospital in time to clarify the cause of the disease and standardize the treatment under the guidance of the doctor.