A red rash on the body may be caused by hives, eczema, contact dermatitis and other diseases, which can be improved by general treatment and medication. 1. Urticaria: If the red rash is caused by urticaria, patients need to avoid contact with the causative agent. Patients can follow the doctor’s advice to take fexofenadine, avastin and other antihistamines, with anti-inflammatory effect. 2. eczema: if eczema caused by a red rash on the body, you need to wear loose and comfortable clothing. Patients can follow the doctor’s instructions for external use of halometasone cream, hydrocortisone cream and other drugs, with antibacterial effect. 3. Contact dermatitis: If the red rash is caused by atopic dermatitis, you need to avoid contact with allergens. Patients can follow the doctor’s instructions for topical hydrocortisone, dexamethasone and other glucocorticosteroids, with anti-inflammatory effect. There are many reasons that lead to a red rash on the body, it is recommended that patients go to the hospital, to clarify the cause of the disease after treatment.