Red rash on the neck, consider the following possibilities: 1. Allergic dermatitis: It may be caused by allergy to sunlight exposure, or wearing scarves made of chemical fiber, wool or silk, or contact with collars made of the above materials. In clinical treatment, anti-allergic treatment is needed, oral levocetirizine hydrochloride granules, 2 times/day, 5mg/time, with compound glycyrrhizin capsules 2 times/day, 2 capsules/time, topical treatment with dinaide ointment 1:1 mixed with zinc oxide borate ointment, 2 times/day, during the above treatment period, it is necessary to avoid spicy and stimulating diet, as well as beef and mutton, seafood hair products. 2, urticaria: can appear red The clinical treatment can be oral Avastin capsules and topical application of Furfurac® lotion for treatment.