The red rash on the body is also itchy, consider the following possibilities: First, it may be erythema multiforme, mainly the appearance of edematous erythema, and part of the erythema can be seen on the iris phenomenon, accompanied by a certain amount of itching, you can take oral levocetirizine hydrochloride capsules, topical dinaide ointment twice a day for the application of treatment. Second, may consider scabies, mainly due to scabies infection caused by an infectious disease, usually itching occurs at night, you can apply Clomid ointment, or sulfur ointment for treatment. For large nodules on the vulva and buttocks, hydrocortisone butyrate ointment can be applied for treatment. Third, consider eczema, mainly due to allergic factors, can be treated with oral diclaretin tablets and topical denuded ointment.