Vesicles on the inner side of the foreskin may be associated with causes such as glans phimosis, chancre, penile cancer, etc., and need to be further differentiated and diagnosed by a doctor. 1. Glans phimosis: it may be manifested as itching of the foreskin and glans, and may be characterized by erosion and ulceration of the skin and mucous membranes. 2. Noma: a small red spot on the external genitalia that can rapidly develop into a painless papule and superficial ulcer. 3. Penile cancer: most often present with penile skin changes, penile swelling and swollen lymph nodes in the groin, in addition to which ulcers may appear on the surface of the penile skin, accompanied by bleeding. It is suggested that there may be other reasons for inner foreskin erosion, and it is recommended to actively consult the doctor under the guidance of professional physicians.