Bowel Issues and Cancer Guide

There are a number ways in which cancer treatment can affect the large bowel and bladder, including constipation, diarrhoea (watery or loose stools),  flatulence, bowel blockage and incontinence. All of these may lead to abdominal soreness, cramps and tenderness. Read our guide to Cancer and Bowel Issues to find out why cancer treatment causes bowel issues, and what you can do about them…

“My treatment caused me gastrointestinal complications… I had read enough to expect this, but the discomfort was still frustrating.”

Why does this happen?

Constipation can be caused by cancer treatment drugs and pain drugs, as well as abdominal surgery. It may also happen with lifestyle changes, for example drinking less liquids, eating less fibre, or being less active.

Flatulence can be caused by alterations to the gut’s ‘good bacteria’, which can be a side effect of certain drugs used in the treatment of cancer or the complications of cancer treatment.

Diarrhoea can be caused by chemotherapy, radiotherapy and some biological therapies. These can all irritate the cells in the lining of the digestive system to cause loose, watery stools.

In addition to the side effects from treatment, abdominal tumours themselves can compress or block the bowel and lead to constipation, diarrhoea and flatulence.

Incontinence can be a direct consequence of tumours in the pelvic region (e.g. gynaecological cancers), or tumours that affect the nerve supply to the bladder (e.g. brain or spinal cord cancers). Chronic coughing from respiratory tumours can also place undue stress on the bladder.

The bladder can become inflamed or irritated directly by radiation to the pelvic area, or as a result of nerve damage from chemotherapy, pelvic surgery may damage both muscles and nerves, and sometimes hormone therapy can cause urethral dryness.

Bowel issues and cancer: What can you do about it?


Fibre supplements

If you are finding it difficult to have enough fibre in your diet, then consider taking fibre supplements, as fibre helps food move through your digestive system. (But check with your doctor first, as if you have adhesions or tumour deposits that narrow your bowel then extra fibre may cause blockages).

Flax seeds and chia seeds

In one trial, eating flaxseeds over a four-week period led to bowel movements increasing by one-third. Some find similar benefits from chia seeds – which may come from the seeds absorbing water as they are digested, becoming gel-like in consistency, and therefore making stools easier to pass.

For more tips and recommendations, visit our constipation category.


Flatulence (excess wind)

Medicinal charcoal

The charcoal absorbs gas in the digestive system, and so is widely recognised to help alleviate wind, as well as indigestion and heartburn. (But check with your doctor first to make sure the charcoal won’t also absorb your medication).

Peppermint oil

Peppermint essence may help calm your digestive system to ease gas and prevent cramps due to its anti-spasmodic effects. You can take it in capsule form or as a tea

For more tips and recommendations, visit our Flatulence category.



Incontinence pads

Pads offer you the protection you need and help you feel secure and dry throughout the day.

Portable urinal

A portable urinal helps to avoid repeated disruptive bathroom trips through the night, or if constantly walking to the bathroom is difficult.

Incontinence disposal bin

The bin provides a discreet and convenient way to dispose of incontinence pads.

Bed pads

These pads absorb liquid to protect beds, mattresses, chairs and wheelchairs and give you peace of mind.

For more tips and recommendations, visit our Incontinence category.



Barrier creams

These are creams or ointments that contain zinc oxide, lanolin, or petroleum jelly, and form a protective barrier on the skin that helps reduce the soreness caused by irritation from frequent loose stools.



Further reading: The link between Lynch Syndrome and Bowel Cancer