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Overactive Bladder Causes
Learning the causes and triggers of overactive bladder (OAB) may help you avoid the condition or manage your symptoms. Get the facts.

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Causes of Overactive Bladder

Overactive bladder (OAB) can be an embarrassing condition. It has many causes. Finding the right treatment depends on knowing why you are experiencing OAB.

Urine is produced by the kidneys and stored in the bladder. Bladder function requires a normal urinary tract and depends on intact communication pathways between the nervous system and bladder muscle (detrusor).

In many cases, the exact cause of the involuntary contraction associated with OAB is unknown. However, there are several known factors that can cause involuntary contraction of the bladder muscle, improper bladder function, and symptoms of OAB. There are also several risk factors that can increase the chances that you will one day develop OAB. Knowing these risk factors and causes will help you prevent the condition or develop the right course of treatment after a diagnosis.

Risk Factors

Certain risk factors associated with OAB like age and gender are beyond your control. Others, like obesity, can be minimized with healthy lifestyle decisions.


Although OAB can occur at any age, the risk of OAB increases as you get older. According to the National Association for Continence (NAFC), one in five adults over the age of 40 is affected by OAB or chronic symptoms of urgency or frequency.


OAB is more likely to affect women than men. The NAFC says that 85 percent of people suffering from OAB in the United States are women. This is largely because menstruation, pregnancy, and menopause can lead to changes in estrogen levels and weakened pelvic-floor muscles. This increases the risk of urge incontinence as a symptom of OAB.

In men, an enlarged prostate (also related to aging) and damage caused by prostate cancer surgery may lead to OAB symptoms.


Excess weight can increase pressure on the bladder. Obesity could also decrease blood flow and nerve activity in the bladder, causing control problems. Losing weight can often completely eliminate the symptoms of OAB.

Causes of Involuntary Bladder Contraction

While the exact cause of OAB sometimes remains a mystery and is usually associated with age, at other times a specific event can trigger the onset of OAB.

Neurological Conditions

Certain neurological conditions may disrupt signals between the nervous system and the bladder muscle and cause symptoms of OAB. These include:

  • Parkinson’s disease
  • multiple sclerosis (MS)
  • spinal injury
  • stroke

Nerve Damage or Trauma

Nerve damage or trauma caused by surgery, certain therapies, or trauma to the pelvis or abdomen can cause loss of control of bladder muscles. This could be temporary — for instance, the moment of impact in a car accident. It can also be longer term, as in the case of a pelvic injury.

Obstructive Conditions

Obstructions such as bladder stones and an enlarged prostate can cause symptoms of OAB. An enlarged prostate can weaken the urinary stream and create urinary urgency. It sometimes causes trouble with urination even when the bladder feels full.

Causes of OAB-Like Symptoms

Other factors and medical conditions can cause symptoms similar to those of OAB. These are often treated with different solutions than common OAB.

Medication Side Effects

Water pills prescribed for other diseases can create side effects with OAB-like symptoms. Pills that have caffeine as an active ingredient also have diuretic properties.

Urinary Tract Infections

Infections of the urinary tract can cause increased activity in the muscle of the bladder wall called the detrusor muscle. This creates an overactive bladder and the urge to urinate more. Unlike most forms of OAB, it can also cause painful urination and a burning sensation. If this is the cause of your symptoms, your doctor will prescribe an antibiotic. The OAB should be gone in a few days. 

Medical Conditions

Various diseases or conditions can also affect or cause incontinence and OAB. When this is the cause of your OAB, treating the underlying disease can lessen symptoms. These conditions include kidney disease, bladder tumors, and diabetes. Diabetes causes nerve damage (diabetic neuropathy), which can affect the nerves that control bladder function and cause urgency and frequency problems.


Menopause causes a sudden drop in the level of estrogen. Lower estrogen levels may cause bladder and urethra muscles to weaken. The weakened muscles can cause leakage from sudden urges associated with OAB (urge incontinence) or from sudden movements such as laughing or sneezing (stress incontinence).


During pregnancy, the uterus expands and can put pressure on the bladder. This may cause sudden urges or incontinence. Women may also experience incontinence problems after childbirth due to weakened pelvic-floor muscles. This is a very common cause of OAB symptoms. It can often be treated by Kegel exercises to strengthen the muscles.

OAB Triggers

Many things can make your OAB worse. The following are considered triggers of OAB, and may temporarily cause increased symptoms.

  • eating acidic foods like tomatoes and citrus fruits
  • excessive drinking of alcohol or caffeinated drinks
  • not drinking enough fluids
  • low fiber intake
  • constipation
  • obesity

Understanding what causes OAB can help you prevent it. By maintaining a healthy weight, for instance, you can avoid obesity-related OAB. If you are already experiencing the symptoms, the cause of your OAB will help your doctor choose the right course of treatment. 

Written by: Rachel Nall, RN, BSN
Edited by:
Medically Reviewed by: University of Illinois-Chicago, College of Medicine
Published: Oct 3, 2014
Published By: Healthline Networks, Inc.
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