Erythema on glans may be caused by trauma, allergy and other conditions, or due to glansitis, syphilis and other diseases. 1. Trauma: Usually when the male glans area is squeezed or hit by external force, resulting in local soft tissue injury, erythema on glans may occur. 2. Allergy: when the male glans is stimulated by other substances such as shower gel, resulting in glans allergy, local erythema may also appear. 3. Glans: usually related to a variety of factors, such as infection, alkaline stimulation, urine stimulation, allergic reaction, trauma, circumcision and so on. Usually patients often appear glans skin mucous membrane edema, erythema, etc., and can be accompanied by itching, pain and so on. Severe cases can also appear oozing, blisters and so on. 4. Syphilis: usually caused by syphilis spirochete infection, and also with sexually active, unprotected sex and other factors. Early congenital syphilis patients often appear skin and mucous membrane damage, such as wrinkles, rash, pustules, desquamation, petechiae, etc. And patients may also appear chancre. And patients can also appear chancre, inguinal lymph node swelling, etc.. It is recommended that patients with symptoms of erythema of the glans, timely and clear diagnosis, and under the guidance of the doctor according to the cause of the disease, to take targeted treatment, so as not to delay the condition.