Causes of urinary incontinence 

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.

Some of the possible causes will lead to short-term urinary incontinence, while others may cause a long-term problem. If the cause can be treated, this may cure your incontinence.

Causes of stress incontinence

Stress incontinence occurs 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). 

Any sudden extra pressure on your bladder, such as laughing or sneezing, can then cause urine to leak out of your urethra.

Your urethra may not be able to stay closed if the muscles in your pelvis (pelvic floor muscles) are weak or damaged, or your urethral sphincter (the ring of muscle that keeps the urethra closed) is damaged.

These problems may be caused by:

  • damage during childbirth, particularly if the child was born vaginally rather than by caesarean section
  • increased pressure on your tummy, for example because you are pregnant or obese
  • damage to the bladder or nearby area during surgery, such as the removal of the womb (hysterectomy) in women or removal of the prostate gland in men
  • neurological conditions, which affect the brain and spinal cord, such as Parkinson’s disease or multiple sclerosis
  • certain connective tissue disorders, such as Ehlers-Danlos syndrome
  • certain medications (see below)

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 known as having an 'overactive bladder'. The reason your detrusor muscles contract too often may not be clear, but possible causes include:  

  • drinking too much alcohol or caffeine
  • poor fluid intake – this can cause strong, concentrated urine to collect in your bladder, which can irritate your bladder and cause symptoms of overactivity
  • constipation
  • conditions affecting the lower urinary tract (urethra and bladder), such as urinary tract infections (UTIs) or tumours in the bladder
  • neurological conditions
  • certain medications (see below)

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 as a result of:

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 below)

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 vagina, in women

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:

Stopping these medications, if advised to do so by a doctor, may help resolve your incontinence.

Who is most at risk?

In addition to the causes mentioned above, there are some things that can increase your risk of developing urinary incontinence without directly being the cause of the problem. These are known as risk factors.

Some of the main risk factors for urinary incontinence include:

  • family history – there may be a genetic link to urinary incontinence, so you may be more at risk if other people in your family have experienced the problem
  • increasing age – urinary incontinence becomes more common as you reach middle age and is particularly common in people over 80
  • having lower urinary tract symptoms (LUTS) – a range of symptoms that affect the bladder and urethra (read about the symptoms of urinary incontinence for more information)

Page last reviewed: 06/10/2014

Next review due: 06/10/2016