Irritable bowel syndrome

Also known as IBS

Irritable bowel syndrome (IBS) is a common condition, associated with a range of symptoms including abdominal cramping, bloating, diarrhoea and constipation. Lifestyle changes, such as changing to a low-FODMAPs diet, keeping active and managing stress, can greatly help improve symptoms and reduce the need for medication.

IBS can be uncomfortable but is usually harmless. Many people worry about cancer and you may feel like you need reassurance that this is not the case. Ask your doctor for a thorough check-up if you are concerned or your symptoms change. 

IBS affects 10-20% of the population and is more common in women than men.

IBS is not the same as inflammatory bowel disease (IBD), which mainly describes two long-term conditions that inflame your gut: Crohn’s disease and ulcerative disease.

When to seek medical advice

You should also see your doctor if have any of the following warning symptoms or signs: 

  • Unintentional or unexplained weight loss.
  • Rectal bleeding that is not due to haemorrhoids.
  • Waking from sleep with pain or the need to use the toilet.
  • Symptoms first beginning in patients aged greater than 50 years.
  • A family history of gastrointestinal cancer, inflammatory bowel disease or coeliac disease.
  • Abdominal lump or mass.
  • Iron deficiency anaemia.

What causes IBS?

The exact cause of IBS is still not certain. IBS may stem from a problem with the nerves that control the bowels. These nerves tell the bowels how fast to remove the waste. They also control pain by sending pain signals to the brain.

  • Nerves that are too active can cause the bowels to remove waste too quickly (diarrhoea).
  • Nerves that aren't active enough can allow waste to stay in the bowels too long (constipation).
  • Very sensitive nerves may send too many pain signals to the brain, causing increased pain.

There is emerging evidence that IBS could be caused by "leaky gut" which may be triggered by foods high in emulsifiers. Westernisation of diet and improved sanitation has also been associated with an increase in IBD (especially in Asian populations). 

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:

  • Bowel movements that occur more or less often than usual.
  • Stool ('poo') that appears less solid and more watery, or harder and more lumpy, than usual, ie:
    • Diarrhoea – having loose, watery stools three or more times a day and feeling urgency to have a bowel movement.
    • Constipation – having fewer than three bowel movements a week. During a bowel movement, 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.
  • Bowel movements that improve the discomfort.

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 the intestines that coats and protects tissues in the gastrointestinal tract.
  • Feeling bloated.

Symptoms usually start in a person's 20's or 30's but can begin at any age.

What triggers symptoms of IBS?

You may have noticed that some foods, medications or stress trigger your symptoms. Common triggers include stress, caffeine, alcohol, fat, dairy products, preserved food, smoking and medications. Additional triggers include hormonal changes such as a woman's menstrual cycle.

You may have some or all of these triggers, and there may be others too. Knowing what your triggers are can help you to manage your symptoms. To help identify your triggers, try keeping a record of your symptoms and looking for any patterns that emerge. 

How is IBS diagnosed?

Your doctor will usually make a diagnosis based on your symptoms. However, the symptoms of IBS are similar to those of other more-serious conditions. If there is uncertainty about whether you have a more serious problem or an infection, you may have one or more of the following tests: sigmoidoscopy, faecal (poo) testing, colonoscopy.

What treatments are there for IBS?

There is no cure for IBS, but there are treatments that can help you control your symptoms. What you do day-to-day – such as what you eat, your level of physical activity and how you manage stress – can make a big difference.

Talking to your doctor about your concerns is also important. A good relationship with your doctor can help you to find the best treatment for your symptoms. If lifestyle changes are not enough, your doctor may prescribe medication.

You may also wish to talk to your GP about taking probiotics, as they may help improve overall symptoms of IBS. Many dietitians and doctors who specialise in gastroenterology (tummy problems) now recommend a low-FODMAP diet as a key part of a treatment plan for people with IBS. 

How can I look after myself IBS?

Lifestyle changes can help control symptoms of IBS. The Self-Help workbook by Manchester University contains useful advice and ideas, such as:

  • Try to eat more fibre and drink more fluids.
  • Learn about IBS diet and food plans – some people do well with increased fibre, others don't.
  • Read up about FODMAP foods and diet.
  • Learn to avoid symptom triggers and reduce stress.
  • Develop techniques to help handle stress – counselling, yoga, breathing exercises, meditation, relaxation tapes and classes and acupuncture may help.
  • Increase your level of physical activity – being more active helps digestion.

Learn more

Irritable Bowel Syndrome  Gastro-Info NZ
IBS  Medline Plus
IBS section  NHS Choices
Irritable Bowel Syndrome section National Digestive Diseases Information Clearinghouse (NIH, USA)

Credits: Health Navigator NZ team. Reviewed By: Dr Derek JY Luo, MBChB (Otago) FRACP, Consultant Gastroenterologist Last reviewed: 23 Sep 2016