Urinary incontinence - Causes 

Causes of urinary incontinence 

Medications that may cause incontinence

Some medicines can disrupt the normal process of storing and passing urine, or increase the amount of urine you produce. These include:

Urinary incontinence occurs when the normal process of storing and passing urine is disrupted.

This can happen for a number of reasons, and certain factors may also increase your chance of developing urinary incontinence.

Causes of stress incontinence

Stress incontinence happens when the pressure inside your bladder as it fills with urine becomes greater than the strength of your urethra to stay closed (the urethra is the tube through which urine passes out of your body).

Your urethra may not be able to stay closed if:

  • your pelvic floor muscles are weak or damaged 
  • your urethral sphincter (the ring of muscle that keeps the urethra closed) is damaged  

Any sudden extra pressure on your bladder, such as laughing or sneezing, can cause urine to leak out of your urethra. The loss of strength in your urethra may be caused by:

  • nerve damage during childbirth 
  • increased pressure on your tummy, for example because you are pregnant or very overweight
  • a lack of the hormone oestrogen in women (less oestrogen is produced after the menopause)
  • certain medications

Causes of urge incontinence

The urgent and frequent need to pass urine can be caused by a problem with the detrusor muscles in the walls of the bladder. The detrusor muscles relax to allow the bladder to fill with urine, then contract when you go to the toilet to let the urine out.

Sometimes the detrusor muscles contract too often, creating an urgent need to go to the toilet. This is called detrusor overactivity. The reason your detrusor muscles contract too often may not be clear, but possible causes include:  

    Some of these possible causes will lead to short-term urinary incontinence; others may cause a long-term problem. 

    If the cause can be treated, this may cure your incontinence.

    Causes of overflow incontinence

    Overflow incontinence, also called chronic urinary retention, is often caused by a blockage or obstruction to your bladder. Your bladder may fill up as usual, but as it is obstructed you will not be able to empty it completely, even when you try.

    At the same time, pressure from the urine that is still in your bladder builds up behind the obstruction, causing frequent leaks.

    Your bladder can become obstructed by:

    Overflow incontinence may also be caused by your detrusor muscles not fully contracting, which means that your bladder does not completely empty when you go to the toilet. As a result, the bladder becomes stretched. Your detrusor muscles may not fully contract if:

    • there is damage to your nerves, for example as a result of surgery to part of your bowel or a spinal cord injury 
    • you are taking certain medications (see box, top left)

    Causes of total incontinence

    Total incontinence occurs when your bladder cannot store any urine at all. It can result in you either passing large amounts of urine constantly, or passing urine occasionally with frequent leaking.

    Total incontinence can be caused by:

    • a problem with your bladder from birth 
    • injury to your spinal cord, which can disrupt the nerve signals between your brain and your bladder 
    • a bladder fistula, which is a small tunnel-like hole that can form between the bladder and a nearby area, such as the vigina, in women

    Risk factors

    Risk factors are not the same as causes. Risk factors are things that increase your chance of developing a condition.

    Risk factors in women

    Risk factors for urinary incontinence in women include:

    • pregnancy – if you developed stress incontinence during pregnancy, or in the six weeks after birth, you are more likely to have stress incontinence five years after the birth  
    • vaginal birth – giving birth vaginally, rather than with a caesarean, may be associated with stress incontinence
    • obesity – having a body mass index (BMI) of 30 or more may also be associated with urinary incontinence (use the healthy weight calculator to work out your BMI) 
    • family history – there may be a genetic link to urinary incontinence, particularly stress incontinence 
    • disability – conditions affecting your brain or spinal cord, such as multiple sclerosis or dementia, may increase your risk of urinary incontinence 
    • increasing age – urinary incontinence becomes more common as you reach middle age and is most common in women over 70   
    • lower urinary tract symptoms (LUTS) – symptoms that affect the bladder and urethra (read about the symptoms of urinary incontinence for more information)

    Risk factors in men

    Risk factors for urinary incontinence in men include:

    • increasing age – urinary incontinence becomes more common as you get older 
    • family history – there may be a genetic link to urinary incontinence, particularly stress incontinence 
    • disability – conditions affecting your brain or spinal cord, such as multiple sclerosis or dementia, may increase your risk of urinary incontinence
    • prostatectomy – an operation to remove your prostate gland, for example if you have prostate cancer, may increase your risk of urinary incontinence
    • lower urinary tract symptoms (LUTS) – symptoms that affect the bladder and urethra (read about the symptoms of urinary incontinence for more information)

    Page last reviewed: 21/09/2012

    Next review due: 21/09/2014

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