A blister on the foreskin can be considered as genital herpes, glans phimosis or angioedema and other diseases. 1. Genital herpes: the main parts of the genitals and perineum, can be seen in the foreskin, the coronal groove, glans and other places to see see clusters or scattered small blisters, the patient conscious of pain, blisters can rupture to form ulcers. 2. Foreskin and glans inflammation: Inattention to local hygiene or pathogen infection can cause inflammation of the foreskin and glans, resulting in redness, swelling and pain of the foreskin and glans, and in severe cases, there are ulcers and erosions. 3. Angioedema: also known as giant urticaria, such as the occurrence of acquired angioedema, can be in the loose parts of the skin such as the vulva, lips, eyelids, etc. Local edema, which can be skin color, shiny surface, can have a sense of elasticity, like blisters performance. The appearance of blisters or other skin lesions on the foreskin, it is recommended to seek medical advice, timely treatment as prescribed by the doctor.