Penis redness, swelling, itching, may be the foreskin glans, urethritis, allergies and other factors do cause. 1. Glans penis: men have long foreskin, do not pay attention to the internal cleaning of the foreskin, may induce glans penis, by inflammatory stimulation, it will lead to local redness, swelling, itching penis. 2. Urethritis: men have unclean sex, may induce urethritis, when the inflammation encroach on the urethral area, will make the glans area red, swollen and itchy symptoms, accompanied by urethral burning sensation, urinary frequency, urinary urgency and other symptoms. 3. Allergic factors: for example, there is an allergic reaction to condoms or toiletries, which can lead to localized redness, swelling and itching of the penis, and the itching is more intense. Penile redness, itching, there may be other reasons, and indicates the existence of abnormalities, it is recommended that men seek medical examination and treatment, to avoid causing other complications.