Changes in bowel habits: what does it mean?

Bowel habits differ from person to person. The average person in the UK opens their bowel once a day but this varies considerably from once a week to as much as three or four times a day. The colour and consistency of stools also vary between individuals. It is important to be aware of what’s normal for you so that you can spot changes in your bowel habits as this can be a sign of an underlying health problem. 

Most often, the causes for changes in bowel habits are not serious, though they may still need treatment. However, in a minority of cases, a change in bowel habits is caused by bowel cancer. This is why any change in your bowel habits that persists for more than three weeks should be investigated to rule out cancer. 

Common causes of changes in bowel habits

Temporary changes in bowel habits are often caused by dietary changes eg when on holiday you may eat less fresh fruit, vegetables and fibre, which can lead to constipation. Certain medications, particularly certain antibiotics, can also change your bowel habits by disrupting the balance of bacteria that normally live in your bowel. 

Bowel infections (gastroenteritis) also lead to changes in your stools, specifically diarrhoea. They can be caused by infection with a virus (eg rotavirus, norovirus), bacteria (eg campylobacter, salmonella and shigella) and parasites (giardia, cryptosporidium and entamoeba histolytica).

Bowel conditions 

Underlying health conditions that affect your bowel can cause longer-term changes in your bowel habits. Common causes include irritable bowel syndrome (IBS) and diverticular disease, while less common causes include inflammatory bowel disease (Crohn’s disease and ulcerative colitis), polyps and bowel cancer.

IBS

IBS causes bloating, stomach cramps, constipation and/or diarrhoea. The exact cause isn’t known though you may find that stress, anxiety and certain foods worsen your symptoms.

Diverticular disease 

This occurs when small pockets (diverticula) develop in the lining of your large intestine, leading to stomach pain during or soon after eating, constipation, diarrhoea and sometimes, blood in your stools. Infection of the diverticula causes diverticulitis, which leads to more severe bowel symptoms and fever. Your risk of diverticular disease increases as you get older. 

Crohn’s disease

This is caused by inflammation of any part of your bowel, usually the large intestine or final section of your small intestine (ileum). This can lead to stomach pain, stomach cramps, anal pain, anal abscesses, anal discharge, diarrhoea, blood in your stools, fatigue, stomach ulcers, pain during sex and unintentional weight loss. 

Ulcerative colitis

This is caused by inflammation of your large intestine (colon) and the formation of ulcers inside your large intestine. This can lead to stomach pain, unintentional weight loss, diarrhoea, blood and/or mucus in your stools, fatigue, anal pain and anal fissures. 

Bowel polyps

These are non-cancerous growths on the lining of your large intestine or rectum. Although they don't usually cause any symptoms, large polyps can lead to diarrhoea, constipation, blood and/or mucus in your stools and unintentional weight loss. 

Bowel cancer

This refers to cancer that starts in your bowel. Changes in your bowel habits are often accompanied by blood and/or mucus in your stools, stomach pain or discomfort and bloating. Your risk of bowel cancer rises significantly after age 50.

Investigating changes in your bowel habits

If you’ve noticed changes in your bowel habits that have persisted for more than three weeks, it’s important to see your GP. 

They will ask you about your symptoms and medical history, and may conduct a physical examination. They may then refer you for a colonoscopy, flexible sigmoidoscopy or gastroscopy.

Depending on the results of your tests, you may need further investigations and be referred to a specialist for treatment. 

Colonoscopy

This procedure involves passing a thin, flexible telescope-like tube with a camera and a light on the end (a colonoscope) into your colon via your anus. A colonoscope is about as thick as your finger and allows your doctor to examine the inside of your colon. 

Before your colonoscopy, you will be given a laxative to clear your bowels. To make your procedure more comfortable and to help you relax, you may be given a sedative, painkillers and/or gas and air.

Your colon is located after your small intestine and leads into your rectum, where your stools are stored before they are passed out via your anus. A colonoscope can be passed all the way to your caecum — the point where your small intestine and large intestine meet.  

Flexible sigmoidoscopy 

This involves passing a device similar to a colonoscope but shorter (flexible sigmoidoscope) into your colon via your anus. It cannot be passed as far into your body as a colonoscope and is used to investigate the lower (left) part of your colon (sigmoid colon), which is connected to your rectum. 

It is less invasive than a colonoscopy and usually causes less discomfort. You will need to take a laxative before your procedure to clear your bowel. 

Gastroscopy

This involves passing a device similar to a colonoscope but shorter (gastroscope) down your throat and into your stomach. A gastroscope is thinner than a colonoscope; about as thin as a pencil. It allows your doctor to investigate your upper gastrointestinal system, which includes your gullet (oesophagus), stomach and the first part of your small intestine (duodenum). 

You will need to fast (refrain from eating any food) for about six hours before your gastroscopy. To make your procedure more comfortable and to help you relax, you may be given a sedative and a local analgesic spray to numb the back of your mouth and the inside of your throat.