This is an inflammation or infection of the prostate gland that can cause swelling and pain in the area behind your penis (just below your bladder), pain or burning when urinating, and painful ejaculation.
Urinary tract infections
You'll want to treat one of these anyway, because they can spread and become very serious.
These are sometimes characterized by itching or burning at the tip of the penis.
Allergies and sensitivity to chemicals or soaps can cause an inflammation of the skin on the penis, especially for men who are uncircumcised.
If you have genital herpes, a sore on your penis can make for very painful sex; it's better for the healing process to refrain from sex in any case. Also, such sores are extremely infectious.
These scaly, red patches may be treated with low-potency steroid creams and are not infectious.
In this condition, the foreskin is too tight to be completely retracted over the head of the penis.
The foreskin is stuck behind the head of the penis and can't be pulled forward.