Irritable bowel syndrome (IBS)

Irritable bowel syndrome (IBS) is a common gut condition, with symptoms including cramping, bloating, diarrhoea and constipation. Diet and lifestyle changes can improve your symptoms a lot.

Key points

  1. IBS is a chronic (ongoing) gastrointestinal (gut) condition. IBS is not the same as inflammatory bowel disease (IBD), which mainly refers to two long-term serious conditions, Crohn’s disease and ulcerative disease.
  2. IBS can be uncomfortable but is usually harmless. Symptoms include bouts of abdominal (tummy) discomfort and pain, bloating and changeable bowel habits from diarrhoea (runny poo) to constipation (hard poo).
  3. IBS affects 1 in 7 people and is more common in women than men, and in those aged under 50.
  4. Changing to a low-FODMAP diet improves symptoms in 3 out of 4 people. Keeping active and managing stress can also help. 
  5. If dietary and lifestyle changes don't help, there are medications to help relieve specific symptoms.

What causes IBS?

The exact cause of IBS is still not certain. However, there is emerging evidence that changes in your gut bacteria and inflammation of your immune system may play a role in its development.

In particular, factors that contribute to IBS are thought to be:

  • sensitivity – you may have a more sensitive gut (sometimes called ‘visceral sensitivity’)
  • digestion speed – the contents of your gut may move unusually quickly or slowly (sometimes called ‘altered gut motility’)
  • bacteria – you may have an imbalance of ‘good’ and ‘bad’ bacteria in your gut (sometimes called ‘dysbiosis’)
  • leaky gut – your gut may be slightly inflamed or ‘leaky’, ie, it may have small cracks or openings that allow partially digested food, toxins and bugs to get through the gut barrier
  • infection – you may have had an infection, such as gastroenteritis, that trigged the IBS. 

What are the symptoms of IBS?

The most common symptoms of IBS are abdominal pain or discomfort, often reported as cramping, along with changes in bowel habits. 

Usually, the pain or discomfort will be associated with at least 2 of the following 3 symptoms:
Feeling better after having a bowel movement
Having bowel movements more or less often than usual
Having diarrhoea or constipation as defined below:
  • diarrhoea – having loose, watery stools 3 or more times a day and feeling urgency to have a bowel movement
  • constipation – having fewer than 3 bowel movements a week. Stools can be hard, dry and small, making them difficult to pass. Some people find it painful and often have to strain to have a bowel movement.
For a diagnosis of IBS, these symptoms must occur at least 3 times a month. 

Other symptoms of IBS may include:

  • feeling that a bowel movement is not completely finished
  • passing mucus – a clear liquid made by your gut that coats and protects its tissues
  • urinary incontinence
  • faecal incontinence
  • feeling bloated.

What triggers symptoms of IBS?

Most people with IBS notice that food triggers symptoms. In particular, a group of short-chain carbohydrates called FODMAPs (fermentable oligosaccharides, disaccharides, monosaccharides and polyols).

FODMAPs are either poorly absorbed in your small intestine or are not digestible.

Because they are poorly absorbed, they reach the end of your digestive system (the large intestine or colon), where most of your gut bacteria live. Here, your gut bacteria ferment them, producing gas. This leads to bloating and flatulence. 

FODMAPS also have an osmotic effect and draw water into your colon. This can cause cramping and more bloating.

Depending on your digestive system, the combination of producing gas and drawing water in can lead to inconsistent or excessive bowel movements, diarrhoea or constipation and tummy pain.

This process is likely to be made worse by stress and lack of physical activity.

When should I seek medical advice?

If you have the symptoms above, see your doctor for a check-up. See your doctor immediately if have any of the following symptoms: 

How is IBS diagnosed?

Your doctor will usually make a diagnosis based on your symptoms. Because the symptoms of IBS are similar to those of more serious conditions, you may have one or more of the following tests: sigmoidoscopy, faecal (poo) testing or a colonoscopy.

There is also breath testing available to see if you have intolerances to fructose or lactose or are a methane producer. Breath testing can also see whether you may have small bowel bacterial overgrowth. This approach involves you eating the substrates individually and then breathing into a machine to assess your response and symptoms to this. This is usually done a few days apart and will enable a suitably qualified dietitian to give you advice on what to avoid to improve your symptoms.

What are the treatments for IBS?

There is no cure for IBS, but there are treatments that can make a big difference. Talk to your doctor about what might be best for you. Treatment options include: 

  • following a low-FODMAP diet
  • reducing stress
  • increasing physical activity
  • taking probiotics
  • taking medication
  • having cognitive behavioural therapy. 

Low-FODMAP diet

Research suggests that 3 in 4 people with IBS get symptom relief, usually within 1–4 weeks, from following a low-FODMAP diet, and that these positive effects can continue long term. It’s best if you can see a dietitian experienced in this diet to help support you make the changes needed. Read more about the low-FODMAP diet and common foods containing FODMAPs. There is also an app developed by Monsash University to help you follow this diet.

Stress

Researchers have also found that reducing your stress can help to ease your symptoms. Read more about stress and how to manage it.

Physical activity

There is also evidence that being more active can help reduce your IBS symptoms. This may be because it helps digested food move through your gut, reducing gas and bloating. Read more about the benefits of physical activity. 

Medicines

Medications are sometimes recommended to help treat IBS symptoms. Some examples include:

  • laxatives for relief of constipation
  • anti-diarrheal medications to relieve chronic diarrhoea
  • anti-spasmodic medications to assist in relieving abdominal pain and cramps
  • antidepressant medication to help with pain.

Read more about medicines for IBS.

Cognitive Behavioural Therapy (CBT)

Because of the connection between the brain and the gut (the gut-brain axis), talking therapy such as CBT, has been found to be helpful in managing IBS symptoms.

Learn more

IBS Central Monash University, Australia
IBS resources Monash University, Australia

References

  1. Irritable bowel syndrome in adults – not just a gut feeling BPAC, NZ, 2014
    Irritable bowel syndrome Crohn’s & Colitis, NZ
  2. Low FODMAP diet efficacy in IBS patients – what is the evidence and what else do we need to know? New Zealand Medical Journal, 2016
  3. Johannesson E, Ringström G, Abrahamsson H, Sadik R. Intervention to increase physical activity in irritable bowel syndrome shows long-term positive effects World J Gastroenterol. 2015 Jan 14; 21(2): 600–608.
  4. Qin H-Y, Cheng C-W, Dong Tang X-D, Bian Z-X. Impact of psychological stress on irritable bowel syndrome World J Gastroenterol. 2014 Oct 21; 20(39): 14126–14131.
  5. Kinsinger SW. Cognitive-behavioral therapy for patients with irritable bowel syndrome: current insights Psychol Res Behav Manag. 2017; 10: 231–237.

Reviewed by

  Dr Derek Luo is a consultant gastroenterologist at Counties Manukau Health and has also been in private practice since 2011. He has a broad interest in general gastroenterology and hepatology and has a sub-specialty interest in pancreatic and hepatobiliary disease.
Credits: Health Navigator Editorial Team . Reviewed By: Dr Derek Luo, consultant gastroenterologist Last reviewed: 04 Jun 2019