Irritable bowel syndrome (IBS)

Irritable bowel syndrome (IBS) affects millions of people around the world. The cause of IBS isn't known, which makes treatment difficult.

What is irritable bowel syndrome (IBS)

Irritable bowel syndrome - or IBS - is a common functional disorder of the colon which results in chronic, painful spasms which can move from one location to another. It can also cause bloating and either constipation or diahorrea, or sometimes both. It is thought to affect at least 10-20% of adults in the US and UK.

Although it can be very painful and life-affecting for some people IBS doesn’t cause any damage to colon. When examined the bowel of someone with IBS looks normal - it just isn’t working in the correct way.

It is usually a lifelong problem which can come and go. There is no cure and no single effective treatment, but many people find ways to help manage their IBS and live a normal life.


What are the symptoms of IBS?

The symptoms of IBS vary from person-to-person and the severity can vary from mild to severe. You may experience periods without symptoms and then have a ‘flare up’ from time to time.

The main symptoms of IBS are:

  • Abdominal pains or cramps. Location of these can vary and come and go and often ease after passing wind or stools
  • Excess gas/bloating
  • Changes in bowel habits. You may get diarrhoea or constipation or fluctuate between the two. You may also experience urgency to go to the toilet

Other symptoms can include:

  • Nausea
  • Headaches
  • Burping
  • Heartburn
  • Changes in appetite
  • Fatigue
  • Back and muscle pains
  • Need to urine more frequently (irritable bladder)
  • Anxiety/depression

IBS is classified into three main types. These are:

  • IBS-D: Stomach pain accompanied by urgency to pass stools and diarrhoea
  • IBS-C: Stomach pain accompanied by bloating and constipation
  • IBS-A: Alternating symptoms of IBS-D and IBS-C

How is IBS diagnosed?

Irritable bowel syndrome can be difficult to diagnose. There isn’t a test which can determine if you have IBS and diagnosis is usually made based on the symptoms you are experiencing and by ruling out other conditions which have similar symptoms, such as Crohn’s disease, ulcerative colitis, bowel cancer, coeliac disease or an infection of the gut.

You will probably have blood and stool tests. These tests will look for markers which could indicate a condition other than IBS. A few people are sent for endoscopy tests in which cameras are inserted into your mouth or anus to look at your digestive tract in more detail.

What causes IBS?

The exact cause of IBS isn’t known. It has been linked to food passing through the gut too quickly or slowly, over-sensitive nerves in the gut, stress and a family history of IBS1.

Some people with IBS find that certain things can trigger their symptoms such as certain foods, medicines or emotional stress, while others notice it starts after a bout of gastroenteritis (food poisoning).

Some of the things that may cause IBS include:

Gut function

Abnormal muscle contractions in the intestines may play a role. Contractions that are stronger and longer than normal can cause gas, bloating and diarrhoea; while weaker contractions can cause food to pass more slowly, leading to constipation.

Nerve abnormalities in the digestive system mean you may experience greater pain than normal when your abdomen stretches as a result of gas or stool.

If the signals between your brain and intestines aren’t co-ordinated well then you could get pain, diarrhoea or constipation

Some people with IBS have low level inflammation in their gut. This inflammation could be playing a role in IBS symptoms.

Disrupted microbiome

Your microbiome is a collection of bacteria which lives in our bodies. The majority of this bacteria lives in your digestive tract (in the colon). Most of this bacteria is beneficial to us, but there is also ‘bad’ bacteria among it. Usually this bad bacteria is kept under control by the beneficial bacteria, however in some people they can have an unbalance of good and bad bacteria causing a disturbed microbiome.

Research has shown that “a disturbed intestinal ecology might promote development and maintenance of symptoms in irritable bowel syndrome (IBS)”2

Family history

Studies have found strong familial IBS links in patients with IBS3. One theory behind the reason for this is that our microbiomes can be passed between family members and that we may live similar lifestyles to those in our family.


Some people report that their IBS started after gastroenteritis (an infection by bacteria or virus). Most people recover from this type of IBS with a bit of time, however some people do not.


You may have SIBO (small intestinal bacterial overgrowth) which can cause IBS-like symptoms. SIBO happens when large amounts of bacteria which would normally live in the colon end up in the small intestine instead.

Testing for causes

Some people opt to pay for private testing to see if they can discover the root cause of their IBS. Companies such as Healthpath* offer testing and analysis of the results for things such as gut health, SIBO, leaky gut and food sensitivities*

IBS triggers

Some of the things which could trigger your IBS symptoms include:


Certain foods or drinks can trigger symptoms for people with IBS, however what these foods are varies from person to person. Common trigger foods and drink include alcohol, caffeine, wheat, dairy, FODMAPs, processed food, sweeteners (such as sorbitol), fizzy drinks.

FODMAPs stands for Fermentable Oligosaccharides, Disaccharides, Monosaccharides and Polyols. They are sugars found in certain carbohydrates and alcohols that are poorly absorbed by the body. When they aren’t absorbed properly they ferment in the intestines, releasing gas which can then cause bloating, wind, pain and sometimes loose stools or diarrhoea.


People with IBS seem to experience worse symptoms at times of stress or anxiety.

Other lifestyle factors

  • Lack of sleep
  • Medications - such as antibiotics, antidepressants
  • Eating too quickly

How is IBS treated?

Because it is not understood what causes IBS the treatments vary greatly from person to person. Some people can control their symptoms with diet, while others need to use medications or work to control stress or anxiety to reduce their flares.

Many people find they have different triggers for their symptoms and a good way to work out what these triggers are is to keep a symptom diary. This involves tracking the symptoms you are having against the food you have eaten, the activities you are doing and how you are feeling. It’s best to keep a diary for several weeks to help see if there are any trends.

Diet and lifestyle changes

Your doctor may refer you to a dietician to look at your diet and see if there is anything you are eating which could be causing your symptoms. Some people are sensitive to certain sugars in foods and are placed on a low FODMAP diet. This diet should not be attempted without the guidance of a trained dietician.

Some things which you could try at home to help include:

  • Eating regular meals more slowly and chewing thoroughly
  • Limiting caffeine (such as from coffee, tea and energy drinks), alcohol and fizzy drinks
  • Increase or decrease the amount of fibre you are eating depending on your symptoms
  • Limit the number of processed foods you eat
  • Cut out artificial sweeteners
  • Eat probiotic foods (such as plain yogurt, sauerkraut) or take a probiotic supplement such as Symprove. There are a growing number of studies into probiotics and IBS which are showing that they may be beneficial in helping symptoms


There are some medications which may help to relieve some of your IBS symptoms. Before taking any of these you should talk to your doctor as some of them shouldn’t be used regularly.

  • Laxatives: These can help with constipation
  • Antispasmodic medication: These can help with pain and trapped wind
  • Anti-diarrhoea medication: These can help to reduce diarrhoea

Other therapies

  • Talking therapy: This can help with anxiety and/or stress
  • Hypnotherapy: Can help to reduce mental triggers which may cause IBS
  • Peppermint oil: Peppermint oil has shown to be effective in helping some people with their IBS symptoms4
  • Exercise: Gentle exercise can help reduce stress and anxiety and improves general well-being. It can also help with constipation
  • Take a look at our tips for reducing bloating and trapped wind

*Please note this is an affiliate link which means if you buy from the company we may receive a commission. You will pay the same price and any commission gained will be used to support IBDrelief's work.




Find this article useful?

Why not sign up to our mailing list and receive regular articles and tips about IBD to your inbox?