A complete guide to IBS

A complete guide to IBS
Kate Hilton, Registered Dietitian
Written by Kate Hilton, RD Published 8 January 2024
Sonia Khan, Pharmacist
Medically reviewed by Sonia Khan, Pharmacist Last reviewed 26 August 2026

What is IBS?

Irritable bowel syndrome (IBS) is a long-term gut condition that causes abdominal pain, bloating, and changes in bowel habit (diarrhoea, constipation, or both). It is now classified as a disorder of gut-brain interaction, which means the symptoms come from a fault in how the gut and the brain communicate rather than from visible damage to the bowel.

There is currently no cure, but IBS can be managed well. For most people, symptoms come and go over years, and dietary changes, lifestyle changes and, where needed, medicines can substantially reduce them.

IBS is common. In the UK, NICE estimates that between 1 and 2 in every 10 people are affected. When the strictest diagnostic criteria are applied, a 2020 study of 73,076 adults across 33 countries found around 4% of people worldwide meet the full definition, with milder forms considerably more widespread. Research consistently points to disturbances within the gut-brain axis as central to the condition, alongside psychological, environmental, and lifestyle factors.

Symptoms of IBS

IBS symptoms are intermittent. Flare-ups can last anywhere from a few hours to days, weeks or months, with quieter periods in between.

Common symptoms

These include abdominal pain, bloating, gas, diarrhoea, and constipation. The pain is typically cramp-like and often changes with a bowel movement. Symptoms range from mild to severe, are frequently heightened by stress or eating, and differ from person to person. Some people experience one symptom, others several at once.

Severe symptoms

IBS is not life-threatening, but severe IBS can seriously impair quality of life, causing persistent pain, urgent and unpredictable bowel movements, and marked fatigue. Severe symptoms deserve proper support from a GP rather than being quietly put up with.

How IBS symptoms differ from other digestive disorders

Unlike inflammatory bowel diseases such as Crohn’s disease or ulcerative colitis, IBS does not cause inflammation, ulcers, or damage to the bowel, and it does not raise your risk of bowel cancer. It is also different from indigestion, which affects the upper stomach rather than the bowel. Because the symptoms overlap with conditions that do need different treatment, a proper diagnosis matters, which is covered below.

Causes of IBS

The cause of IBS is not completely understood. Research suggests a combination of factors is involved.

  • Gut-brain axis disruption: the gut and brain constantly exchange signals in both directions. In people with IBS, this signalling becomes disordered, which changes how the bowel moves and how strongly sensations from it are felt. A 2020 review in The Lancet describes this disordered communication as the best-established mechanism in IBS.
  • Abnormal contractions within the intestine: the walls of the intestine are lined with muscle that contracts to move food along. Contractions that are stronger, weaker, or longer than usual can cause bloating, diarrhoea and constipation.
  • Visceral hypersensitivity: an increased sensitivity to sensation in the gut, meaning the normal working of your digestive organs can register as pain and discomfort.
  • Infections: IBS can develop after a bout of gastroenteritis caused by a virus, bacteria or parasite. This is called post-infection IBS and is one of the best-described risk factors for the condition.
  • Changes in the gut microbiome: a 2019 systematic review of 24 studies found that people with IBS tend to carry a different balance of gut bacteria from people without it, with some helpful groups such as Bifidobacterium reduced. Researchers have not yet established whether these differences cause IBS or result from it. Our guide looks in more detail at whether your gut microbiome could be triggering your IBS symptoms.

Triggers

Dietary triggers

  • FODMAPs: short-chain carbohydrates (sugars) that are poorly absorbed by the small intestine. Gut bacteria ferment them, producing gas, and they draw water into the bowel, which can lead to diarrhoea. Foods high in FODMAPs include lactose-containing dairy, wheat-based cereals, onions, garlic, and various fruits and vegetables. A 2021 pooled analysis of 13 trials in 944 people found a diet low in FODMAPs ranked first among dietary approaches for improving overall IBS symptoms, pain and bloating, though it should be followed with dietetic support and is not intended as a permanent way of eating.
  • Gas-producing foods: brassica vegetables, beans, lentils and pulses can increase gas production in the large intestine, leading to wind and bloating.
  • Inadequate or sub-optimal fibre intake: fibre softens a hard stool, thickens a loose one, and encourages the intestine to move food along effectively. Different fibres ferment to different degrees, so adjusting the type of fibre you eat can also reduce gas and bloating.

Other triggers

  • Stress and anxiety: psychological stress can heighten IBS and other gut symptoms by affecting how the bowel moves and how sensitive it is.
  • Hormonal changes: fluctuations during the menstrual cycle can affect bowel function, one of the reasons IBS symptoms often vary across the month in women.

Who is most at risk?

  • Younger adults: IBS most commonly develops in late adolescence or early adulthood, and new diagnoses are less common after 50. New bowel symptoms starting over 50 need checking by a GP rather than being put down to IBS.
  • Women: a meta-analysis of 80 studies covering 260,960 people found IBS is around one and a half times more common in women than in men. Hormonal fluctuations are thought to contribute. Our medical guide, Understanding IBS in Women, details the symptoms, challenges and management techniques for women with IBS.
  • Family history: genes play a modest but real part. A 2021 genetic study of 53,400 people with IBS identified six regions of DNA linked to the condition, several shared with anxiety and mood disorders. Shared family lifestyle and environment are likely to contribute as well.
  • Psychological factors: anxiety, depression, and a history of trauma are all more common in people with IBS. The genetic work above suggests this reflects shared underlying pathways rather than one simply causing the other.
  • A recent gut infection: covered below under sudden onset.

How is IBS diagnosed?

Diagnostic criteria: clinicians use the Rome IV criteria. These require recurrent abdominal pain on average at least one day per week in the last three months, associated with two or more of the following: the pain is related to a bowel movement, there is a change in how often you pass stools, or there is a change in the form or appearance of your stools. Symptoms should have started at least six months before diagnosis.

The UK pathway: in the UK, a GP can usually make a positive diagnosis of IBS from your symptoms and history, following NICE guidance, without referral to a specialist. There is no laboratory test that confirms IBS. Instead, a small set of tests rules out conditions that can look similar. These typically include blood tests (a full blood count and inflammation markers), a blood test for coeliac disease, and often a stool test called faecal calprotectin, which helps distinguish IBS from inflammatory bowel disease. A colonoscopy is not routinely needed unless warning signs are present. If any of the red flags listed later in this guide appear, your GP will refer you for further investigation rather than diagnosing IBS.

Gut microbiome test: a gut microbiome test does not diagnose IBS, and it cannot predict whether you will develop it. What it shows is the current state of your gut bacteria, including whether the balance of species looks similar to or different from what is typically seen in a healthy gut. That information is relevant because research links an imbalance of gut bacteria, known as dysbiosis, with IBS, although scientists have not yet established which comes first. Diagnosis itself stays with your GP.

If you are weighing up whether that kind of insight would be useful to you, our guide explains what gut microbiome health tests are and whether they are worth it.

Identifying IBS from other digestive disorders

IBS has a recognisable pattern that helps separate it from other digestive disorders. The abdominal pain is cramp-like, often eases after a bowel movement, and is closely tied to changes in bowel habit, such as alternating constipation and diarrhoea. Symptoms that do not fit this pattern, such as bleeding, weight loss or night-time symptoms, point away from IBS and need investigating.

Treatment and management

Dietary management of IBS

Foods to avoid: this is highly individual and best worked through with a dietitian, who can help you identify your specific triggers safely. Potential triggers include gas-producing foods, FODMAPs and different types of fibre in varying quantities. Understanding your own triggers is central to managing IBS long term.

Beneficial foods for IBS: foods high in soluble fibre, low-FODMAP fruits and vegetables, and lean proteins suit many people with IBS, though tolerance varies.

The role of fibre:

A high-fibre diet can help manage IBS symptoms, provided you are eating the right type of fibre for the symptoms your IBS causes.

Soluble fibre can help with IBS symptoms by softening hard stools and thickening loose ones. The trial evidence backs this up. A pooled analysis of 14 trials in 906 people found soluble fibre, such as ispaghula, improved IBS symptoms, while bran, an insoluble fibre, showed no benefit. NICE gives matching advice, recommending soluble fibre where fibre is needed and discouraging bran.

Increase soluble fibre gradually. A sudden jump can temporarily worsen symptoms.

The fermentability of the fibre you eat also matters. Many fibres are moderately to highly fermentable, and eating a lot of them can increase gas, bloating and pain.

Read our complete guide on effectively managing IBS through diet.

Lifestyle and home remedies

Stress management: relaxation exercises, meditation, yoga, and cognitive behavioural therapy can help manage stress-related triggers. The British Society of Gastroenterology’s 2021 guideline recommends psychological therapies, including CBT delivered for IBS and gut-directed hypnotherapy, for people whose symptoms have not improved after 12 months of other treatment, and notes they can be considered earlier if the person prefers.

Exercise: regular physical activity can improve bowel function and reduce stress.

Sleep and routine: adequate sleep and regular mealtimes help regulate bowel function.

Medical treatments for IBS

Medications: options include fibre supplements, laxatives, anti-diarrhoeal medicines, antispasmodics, and certain antidepressants, which are used at low doses for their effect on gut pain signalling rather than for mood. Which is suitable depends on whether your IBS is mostly diarrhoea, mostly constipation, or mixed, and is a decision for you and your GP.

Other approaches: peppermint oil capsules help some people with cramping pain. Some people also try live bacteria supplements; the evidence here is mixed, and no particular product can be singled out as effective, so UK guidance suggests that anyone trying them does so for up to 12 weeks and stops if there is no benefit.

Medicine is not the first line treatment option for IBS. Your GP will usually advise dietary and lifestyle changes to reduce your symptoms before recommending or prescribing medicine.

Living with IBS and outlook

IBS does not reduce life expectancy, but it can affect quality of life. With no cure currently available, managing the condition well means combining approaches rather than relying on one.

Alongside diet, lifestyle and any prescribed treatment, three things consistently help:

  • Education and awareness: understanding the nature of IBS and recognising your personal triggers makes the condition easier to control.
  • Regular medical follow-up: keep your GP informed, particularly if symptoms change or stop responding to your usual management.
  • Support systems: IBS support groups and psychological counselling give people space to share coping strategies that work.

Managing IBS takes patience, because different strategies work for different people and finding yours can take time. With the right approach, many people with IBS gain significant relief and lead full, normal lives.

When to see a doctor

See a GP if your symptoms are persistent, are affecting your daily life, or have changed from your usual pattern. Book an appointment promptly if you notice any of the following, because they are not typical of IBS and need proper investigation:

  • Blood in your stool, or bleeding from your bottom
  • Unexplained weight loss
  • A change in bowel habit lasting more than three weeks, particularly if you are over 50
  • Difficulty swallowing
  • Persistent vomiting
  • A lump or swelling in your tummy or back passage
  • Signs of anaemia, such as unusual tiredness, paleness or breathlessness
  • Symptoms that wake you at night, including needing to open your bowels
  • A family history of bowel or ovarian cancer
  • New, persistent bowel symptoms starting for the first time over the age of 50

Most people with these symptoms will not have anything serious, but they are the signs a GP needs to check before IBS can safely be diagnosed or assumed.

Can you suddenly develop IBS?

Yes. IBS can begin abruptly, most often after a severe bout of gastroenteritis, when it is known as post-infection IBS. A meta-analysis of 45 studies covering 21,421 people found that around 1 in 10 people who have a significant gut infection go on to develop IBS within a year, roughly four times the risk of people who have not had one. Infections caught abroad are a recognised route, and our guide to gut infections picked up while travelling covers what to look out for. Sudden onset can also follow significant stress or changes in diet, while in other people IBS develops gradually.

Can you prevent IBS?

There is no proven way to prevent IBS, and no test or product can honestly claim to stop it developing. What you can do is reduce the impact of the things known to drive symptoms:

  • Diet: identifying and moderating your trigger foods, such as high-gas foods, wheat-based products or lactose if you are sensitive to them, can significantly reduce symptoms.
  • Stress management: regular exercise, mindfulness practices, or counselling all help, given how closely stress and gut symptoms interact.
  • Understanding your gut: because research links an imbalanced gut microbiome with IBS, some people choose to check the state of theirs, particularly after a gut infection or a long period of symptoms. Learn more about testing your gut microbiome for IBS, including what a test can and cannot tell you.

Can IBS be cured?

Currently, there is no cure for IBS. Many people manage their symptoms effectively through lifestyle modifications, dietary changes, and, in some cases, medication. Treatment is individual and often needs tailoring over time, combining dietary adjustments, stress management, and sometimes psychological therapy.

Can IBS go away on its own?

IBS is a long-term condition, but its symptoms fluctuate. Some people have periods of remission where symptoms are minimal or absent, occurring spontaneously or following lifestyle changes. Symptoms can also return or worsen, often triggered by stress or diet. A long-term management plan agreed with your GP is the most reliable way to keep the quiet periods long and the flare-ups short.

Conclusion

IBS is a chronic but manageable condition. A confirmed diagnosis from your GP, a clear picture of your personal triggers, and a management plan that combines diet, lifestyle and, where needed, medicine are what make the difference to living well with it.

Sources

This guide is for information only and does not replace advice from your GP, pharmacist or dietitian.

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