What’s Causing This Sore on My Penis? It’s not uncommon to have small bumps or spots on your penis. An outbreak of genital herpes can cause painful, blistering, scab-like sores on your penis head, shaft, and base.
Rubbing very hard on your penis — whether during sex or itching or irritation inside your penis; sores on your penis, rectum, or mouth.
Non-STD lesions on the penis include the common condition of folliculitis, which is a bacterial infection of a hair follicle, usually caused by friction or irritation. Painful, tiny clusters of small blisters may indicate genital herpes. Other ulcers or sores on the penis, whether.