Urinary incontinence occurs when the muscle (sphincter) that holds your bladder's outlet closed is not strong enough to hold back the urine. This may happen if the sphincter is too weak, if the bladder muscles contract too strongly, or if the bladder is overfull.

A man may have one or more types of incontinence, and each type may have a different cause.

• Stress incontinence occurs when the muscle (sphincter) surrounding the urethra opens at an inappropriate time. This can happen when you laugh, sneeze, cough, lift something, or change posture. Stress incontinence can be caused by surgery to treat an enlarged prostate or prostate cancer, radiation therapy to treat prostate cancer, or removal of the prostate. For more information, see the topics Benign Prostatic Hyperplasia (BPH) or Prostate Cancer.
• Urge incontinence is caused by bladder contractions that are too strong to be stopped by the sphincter. Often the urge is a response to something that makes you anticipate urination, such as waiting to use a toilet, unlocking the door when returning home, or even turning on a faucet. The bladder contractions can be caused by many conditions, including:
  • Urinary tract infection.
  • Bowel problems, such as constipation.
  • Prostatitis, a painful infection of the prostate gland.
  • Certain neurological conditions that affect nerve signals from the brain, such as Parkinson's disease or stroke.
  • Kidney or bladder stones.
  • Blockage due to prostate cancer or benign prostatic hyperplasia (BPH).
  Overactive bladder is a kind of urge incontinence. But not everyone with overactive bladder leaks urine. For more information, see the topic Overactive Bladder.
• Overflow incontinence usually is caused by obstruction of the urethra from BPH or prostate cancer or when the bladder muscles contract weakly or don't contract when they should. Other causes include:
  • Narrowing of the urethra (stricture).
  • Medicines, such as antihistamines, and decongestants.
  • Nerve conditions, such as diabetes or multiple sclerosis.

Functional incontinence is a rare form of incontinence caused by physical or mental limitations that restrict a man's ability to reach the toilet in time.