font size

Overactive Bladder (OAB)

Medical Author:
Medical Editor:
Medical Editor:

Overactive bladder facts

  • Overactive bladder results from sudden, involuntary contraction of the muscle in the wall of the urinary bladder.
  • Overactive bladder is a form of urinary incontinence.
  • Overactive bladder is not a normal part of aging.
  • Treatments available for overactive bladder include pelvic-muscle strengthening, behavioral therapies, medications, neuromodulation, and surgery.

What is an overactive bladder?

An overactive bladder is a condition that results from sudden, involuntary contraction of the muscle in the wall of the urinary bladder. Overactive bladder causes a sudden and unstoppable need to urinate (urinary urgency), even though the bladder may only contain a small amount of urine.

Overactive bladder is also referred to as urge incontinence and is a form of urinary incontinence (unintentional loss of urine). Another common type of urinary incontinence is called stress incontinence, which is caused by anatomic weakness in the structures that prevent the bladder from leaking. In general, urinary incontinence is more common in women compared to men.

Although it can happen at any age, overactive bladder is especially common in older adults. Overactive bladder, however, should not be considered a normal part of aging.

What are the causes of overactive bladder?

Overactive bladder is typically caused by spasms of the muscles of the bladder, resulting in an urge to urinate (hence, urge incontinence). Overactive bladder is primarily a problem of the nerves and muscles of the bladder. Detrusor is one of the major muscles of the bladder. Its contraction in response to filling of the bladder by urine is one the steps in the normal process of urination. The contraction and relaxation of the detrusor muscle is regulated by the nervous system. Approximately 300 cc of urine in the bladder can signal the nervous to trigger muscles of the bladder to coordinate urination. Voluntary control of the sphincter muscles at the opening of the bladder can hold the urine in the bladder for longer. Up to 600 cc of urine can be contained in a normal adult bladder.

Overactive bladder typically results from inappropriate contraction of the detrusor muscle regardless of the amount of urine.

The common abnormalities of the nervous system that cause of overactive bladder are

There are also some causes of overactive bladder and urge incontinence with a normal nervous system. For example, urinary tract infection, bladder stones, or bladder tumors can cause also cause overactivity of the detrusor muscle, leading to overactive bladder.

Sometimes no apparent cause of overactive bladder can be determined (idiopathic overactive bladder).

Medically Reviewed by a Doctor on 1/8/2014


Women's Health

Find out what women really need.

Use Pill Finder Find it Now See Interactions

Pill Identifier on RxList

  • quick, easy,
    pill identification

Find a Local Pharmacy

  • including 24 hour, pharmacies

Interaction Checker

  • Check potential drug interactions
Search the Medical Dictionary for Health Definitions & Medical Abbreviations