There are several possibilities for red rash and itching on the body as follows: 1. Erythema multiforme. It is mainly edematous erythema, and the surface can appear iris phenomenon, accompanied by itching sensation. You can take oral loratadine capsules, 1 capsule once a day, with compound glycopyrrolate capsules, 3 times a day, 2 capsules once. Topical Denide ointment, 1:1 mixed with zinc oxide borate ointment, 2 times a day for application treatment. 2, urticaria. The appearance of a red rash such as a wind-blown mass and the phenomenon of skin scratching disorder, accompanied by a certain amount of itching. It can be treated with oral fexofenadine hydrochloride tablets, 1 tablet 3 times a day, combined with Avastin capsules, 1 capsule 3 times a day, and also with topical glyburide lotion. While treating the above two diseases, you need to avoid alcohol, spicy and stimulating foods, and hairy products such as beef, mutton and seafood.