Prostatitis is a usually painful condition of the prostate gland, the small walnut-shaped organ that lies just below a man's bladder. The prostate gland produces most of the fluid in semen.

Often the cause of prostatitis is not known. Many men with prostatitis have no signs of inflammation, so no exact cause can be determined. Prostatitis may be caused by an infection or by inflammation not related to infection. It may be acute (short-term) or chronic (long-term).

Symptoms of prostatitis include:

• An urge to urinate often but passing only small amounts of urine; feeling an urgent need to urinate; a burning sensation when urinating; and the inability to empty the bladder completely.
• Trouble starting urination, interrupted flow (urinating in waves instead of in a steady stream), weaker-than-normal urine flow, and dribbling after urinating.
• Pain or discomfort in the lower back; in the area between the scrotum and the anus; in the lower abdomen, scrotum, or upper thighs; or above the pubic area.
• Excessive urinating at night.
• Prostate pain or vague discomfort on ejaculation.

Treatment for prostatitis varies according to the cause. In many cases, medicine is needed.