What causes overactive bladder?

If you have an overactive bladder (OAB), learning the cause can help you manage it better. Sometimes your doctor won’t be able to find a cause. In other cases, you and your doctor can pinpoint an underlying condition, which may be treatable.

To work properly, your bladder relies on a healthy urinary tract. It also needs intact communication pathways between your nerves and bladder muscle. Several conditions can affect these parts of your body and cause your bladder muscle to contract involuntarily. This can trigger symptoms of OAB.

OAB is caused by involuntary muscle contractions in your bladder muscles, whether or not your bladder is full. The exact cause of these contractions is sometimes impossible to identify. In other cases, you and your doctor can identify the underlying cause.

Neurological conditions

Some neurological conditions can disrupt the signals between your nerves and bladder muscle. These include:

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

Nerve damage

Other conditions can cause nerve damage and lead to OAB. These include:

  • trauma to your spine, pelvis, or abdomen, caused by injuries or surgeries
  • diabetes neuropathy, a complication of diabetes
  • infections in your brain or spinal cord
  • neural tube defects

Sometimes OAB-like symptoms are actually caused by something else.

Urinary tract infection

A urinary tract infection (UTI) can cause increased activity in the muscle of your bladder wall. This causes your bladder to become overly active, triggering the urge to urinate more. Unlike OAB, a UTI often causes pain or a burning sensation during urination.

If you have a UTI, your doctor can help diagnose the cause and prescribe treatment. They can prescribe antibiotics that quickly clear up most symptoms.

Side effects from medications

If you’ve been taking water pills, caffeine pills, or other medications that increase your urine output, they can cause OAB-like symptoms. If you need to take your medication with lots of fluids, the fluids can also increase your urine production dramatically and cause urgency (the sudden need to go) and incontinence (loss of bladder control).


Blockages or other abnormalities in your urinary tract can cause symptoms similar to OAB. These include bladder stones, enlarged prostate, and tumors. An enlarged prostate can also weaken your urinary stream and cause other symptoms, including urgency.

If you’re a woman, OAB-like symptoms may indicate menopause or pregnancy.


Menopause causes a sudden drop in the level of estrogen in a woman’s body. Lower estrogen levels can cause your bladder and urethra muscles to weaken. This can lead to sudden urges to urinate and urine leakage, a condition known as urge incontinence.

You may also develop stress incontinence with menopause. In this condition, laughing, sneezing, and similar movements put pressure on your bladder and lead to urine leakage.


During pregnancy, a woman’s uterus expands. This can put pressure on your bladder and cause sudden urges to urinate, or incontinence. You might also experience incontinence after childbirth, due to weakened pelvic floor muscles. This is a common cause of OAB-like symptoms and is treatable with Kegel exercises and other therapies designed to strengthen your muscles.

Certain risk factors affect your chances of developing OAB. Some of them, such as age and gender, are beyond your control. Others, such as obesity, are preventable through healthy lifestyle choices.

Risk factors for OAB include:

  • Age: OAB can occur at any age, but your risk increases as you get older. Age also raises your risk of other conditions that affect bladder control.
  • Gender: Women are more likely than men to be incontinent, reports the National Institute on Aging. In part, this reflects how menstruation, pregnancy, and menopause affect women’s hormone levels and pelvic floor muscles.
  • Obesity: Carrying excess weight puts pressure on your bladder. Obesity may also lead to conditions that can affect blood flow and nerve activity in your bladder.

If you have OAB, there are many possible triggers for your symptoms. These include:

  • eating acidic foods, such as tomatoes and citrus fruits
  • drinking too much alcohol or caffeinated drinks
  • not drinking enough fluids
  • not getting enough fiber in your diet
  • constipation

Identifying and avoiding your triggers can help reduce your OAB symptoms.

Understanding the causes and risk factors for OAB may help you avoid developing it. If you have OAB, diagnosing the cause and identifying triggers can help you manage your condition. Healthy lifestyle choices are important. Try to maintain a healthy weight, eat a well-balanced diet, and get regular exercise. Stay in touch with your doctor, who can help you manage your symptoms and treat any underlying health conditions.