Blisters on the penis may be caused by genital herpes, glans phimosis, scrotal eczema and other causes. 1. Genital herpes: blisters on the penis may be caused by genital herpes, which is a sexually transmitted disease caused by the herpes simplex virus. Clinical manifestations are clusters or scattered small blisters around the external genitalia or anus, which break down and form erosions after 2 to 4 days, and may be accompanied by pain, fever, headache, fatigue and other systemic symptoms. 2. Glandulitis: blisters on the penis may be caused by glandulitis, which is an inflammation of the inner plate of the foreskin and the head of the penis. Clinical symptoms are redness of the foreskin of the penis, glans, and white cheese-like discharge. 3. Scrotal eczema: blisters on the penis may also be caused by scrotal eczema, scrotal eczema lesions are confined to the scrotal skin, can be extended to the perianal area or penis. The manifestation of the scrotum and penis skin blisters, redness, swelling, oozing, vesicles, itching and so on. Patients with symptoms of blisters on the penis, it is recommended to go to the hospital in a timely manner, under the guidance of the doctor to clarify the cause and treatment.