Edematous erythema with redness and itching in the coronal groove of the glans may be caused by factors such as prepuce and glansitis, allergy and syphilis. 1. Foreskin glansitis: the presence of prepuce as well as long foreskin, do not pay attention to the lower body hygiene, may induce fungal or bacterial foreskin glansitis, will make the glans coronal erythema, accompanied by redness, itching, tingling and other symptoms. 2. Allergy: contact with allergy-prone substances, such as poor quality condoms, may make the glans coronal area of the allergic reaction, may appear edematous erythema, accompanied by itching, redness and other symptoms. 3. Syphilis: belongs to a sexually transmitted disease, mostly related to unclean sex, can make the genital area appear small erythema, and will rapidly develop into an ulcer, there will be itching, tingling and other symptoms, and highly infectious. Edematous erythema in the glans, redness and itching, indicating the existence of abnormalities, it is recommended to go to the regular hospital for appropriate examination and treatment.