There's a variety of causes for changes in bowel function. It can be structural, such as nerve or muscular damage caused by surgery or injury. Some medications influence the gut's functioning.

Problems can arise due to lack of exercise, diet and excessive weight. Travelling and changes in habits contribute to the gut's health and can cause temporary problems.

Not drinking enough fluids can cause constipation. Alcohol, especially beer, can make trouble for your gut.

Constipation

Constipation can create a blockage in the bowel, preventing anything but watery discharge passing around it. This watery stuff is hard to control and can easily leak from the anus.

Surgery such as for haemorrhoids, abscesses, fistula or repair of tears can all lead to painful episodes on the toilet. Reluctance to go because of the pain causes people to hold it in, leading to blockages and constipation.

Conditions such as irritable bowel syndrome (IBS) also cause both constipation and diarrhoea.

Bowel control problems can happen because of repeated straining and pushing due of ongoing or recurrent constipation.

This straining can damage the colon, the rectum, muscles and the anus, which then adversely affects bowel control.

Diarrhoea

Diarrhoea is a cause of bowel incontinence, but also a symptom of something else.

Acute (sudden) attacks of diarrhoea, such as when you get a stomach bug, usually go away within a few days.

Caffeine, artificial sweeteners, too much alcohol and sweets can all cause bouts of diarrhoea.

Chronic diarrhoea (recurrent or ongoing) can be caused by a range of things, such as lactose intolerance, inflammatory bowel diseases, such as Crohn's disease or ulcerative colitis, or IBS.

Childbirth

Pregnancy can strain the pelvic floor muscles and childbirth can stretch, weaken and sometimes tear them, and damage nerves.

Surgical cuts during childbirth can also cause problems later on.

Injury due to procedures during childbirth can cause damage to the muscles sometimes only showing itself decades later.

Muscles

One effect of straining due to constipation is damage to areas of the colon as well as the muscles.

Surgery in the pelvic area, colon and anus, such as for fistula, haemorrhoids or abscesses, can also cause muscular damage.

Prolapse

Occasionally people develop what's known as a prolapse, which will affect continence. This is when an organ moves out of place or slides in on itself.

For instance, the rectum can displace and bulge into the vagina, this is called rectocele.

Intussusception is when the rectum slides in on itself.

Prolapse is corrected with surgery.

Surgery and storage capacity

Scarring from surgery or disease can reduce the elasticity of the bowel, reducing capacity.

Nerve damage

The rectum, anus and the muscles involved in bowel control and urination are dependent on sensory communications to the brain by nerves. When these nerves or pathways are damaged problems arise.

Damage can be due to surgical procedures, accidents, such as spinal injury, or because of conditions that affect the nervous system, such as multiple sclerosis.

Conditions and disease

People with certain conditions may require continence control support, such as with diabetes or spina bifida, or neurological problems such as caused by stroke, Parkinson's and Alzheimer's disease.