Allergic glans is mostly caused by taking certain drugs or food, contacting certain allergens and so on. 1. Drug or food allergy: when taking certain drugs or food with different degrees of allergic reaction, the allergic reaction may appear in the glans leading to localized redness, swelling, blisters, itching and other allergic inflammatory reactions in the glans. 2. Contact with certain allergens: glans skin contact with certain allergens such as underwear mites, willow floss or condom lubricants, can cause allergic glans, glans redness, swelling, itching, erosion and other symptoms. Allergic glans need to go to the hospital in time for examination and treatment, get rid of allergens, pay attention to private hygiene and cleanliness, and change underwear frequently.