Erythema on the body without pain or itching may be due to pityriasis rosea, hemangioma, allergic purpura and other diseases. 1. pityriasis rosea: the cause of pityriasis rosea is not yet clear, it may be caused by viral infection, drugs, immune dysfunction and other factors. Patients will appear red spots, scales, plaques and other symptoms, some patients manifested as red spots on the body without pain and itching. 2. Hemangioma: the etiology and pathogenesis of hemangioma have not been clearly defined, and the etiology may be related to chronic inflammation, trauma and endocrine. It is also believed that hemangioma is congenital benign tumor, which is related to embryonic residue, and the patients will have congestive patches and strawberry-like plaques on the skin without pain or itching. 3. Anaphylactic purpura: Anaphylactic purpura may be caused by infection, heredity, drugs, immune disorders and other factors. Patients will appear purple-red papules, and do not fade when pressed, and a few patients are not accompanied by pain and itching. There are many reasons that lead to red spots on the body that do not hurt or itch, so patients can go to the hospital and find out the cause of the disease.