A red rash on the body without pain or itching may be caused by cherry angioma, thrombocytopenic purpura and other diseases, and it is recommended that patients take general treatment, medication, surgery and other ways to improve. 1. Cherry hemangioma: long red rash on the body without pain and itching is considered to be caused by cherry hemangioma, the disease generally do not need treatment, if you think it affects the aesthetics, the patient can take laser treatment. 2. Thrombocytopenic purpura: long red rash on the body without pain and itching may be caused by thrombocytopenic purpura, patients can be injected with dexamethasone, prednisone and other glucocorticoid drugs, which have the effect of anti-inflammatory and immunosuppressive. Immunoglobulin can also be injected to promote the recovery of the rash. There are more reasons that lead to a red rash on the body without pain or itching, so it is recommended that patients seek medical examination to clarify the cause of the disease and cooperate with the doctor for standardized treatment.