What is IBS?

26 February 2024

Irritable bowel syndrome (IBS) is a common condition that affects the digestive system. It can involve pain and discomfort in the abdominal area, as well as irregular or unpredictable bowel movements.

It’s estimated that between five and ten per cent of the world’s population has IBS and that most are under the age of 50.1 Despite it being so common, the exact causes of IBS are unknown and there’s no cure. It can be a frustrating condition to live with, but the symptoms are manageable with medication, diet and lifestyle changes.

If you’re struggling with IBS, or wondering if you have it, we’ve put together this guide to help you understand, recognise and manage the symptoms and triggers.

Gut feelings – IBS symptoms

IBS is unpredictable, inconsistent and inconvenient. The symptoms can come and go. They can last for months at a time or flare up and disappear in the space of a day. Symptoms can also interchange and be contradictory – one flare-up could involve diarrhoea and the next time you might be constipated.

IBS is different for everyone, but some of the main symptoms include:

  • stomach pain or cramps, which usually feel worse after eating and better after a bowel movement
  • a bloated or swollen tummy, which makes you feel uncomfortably full
  • changes to the regularity of your normal bowel movements and not always being able to control them (ie. diarrhoea and constipation)
  • flatulence
  • tiredness and a lack of energy
  • feeling nauseous
  • backache
  • urinary problems, such as having sudden urges to urinate, needing to go more often or feeling as though you can’t fully empty your bladder.

It’s not difficult to understand how these symptoms can have a profound impact on daily life, particularly as they’re so unpredictable. On a day-to-day basis, IBS can range from being a mild inconvenience to severely debilitating, and in the long-term it can affect us emotionally and disrupt our social and professional lives.

IBS triggers

While the exact cause of IBS is unknown, its symptoms can be triggered by various outside factors. And, because the gut interacts with the brain and the nervous system, ‘flare-ups’ can arise as a result of lifestyle factors, as well as diet.

>Read more on the gut-brain connection

Your gastrointestinal system may be more sensitive to certain bacteria or hormonal changes, so you may be more susceptible to certain triggers and not affected by others. Common IBS triggers include:

  • alcohol
  • caffeine
  • spicy food
  • fatty food
  • stress
  • depression and anxiety
  • medication.

Unfortunately, there’s also the chance that symptoms can arise or flare up without any obvious trigger. So, while diet and lifestyle changes can help, you may also need to learn to manage the symptoms if you suffer with IBS.

Treating and managing IBS

As mentioned previously, the exact cause of IBS is unknown and there’s no medication or diet change that can cure it. Treating IBS is about managing the symptoms and trying to recognise and avoid triggers.

The good news is there are plenty of things you can do. As IBS can affect everyone differently, there isn’t a one-size-fits-all course of action. You can speak to your GP about more specific treatment options, but here’s a handy list of NHS-recommended2 DOs and DON’Ts that serve as a good starting point:

  • DO cook homemade meals using fresh ingredients when you can
  • DON’T delay, skip or rush meals
  • DO try and avoid eating too many fatty, spicy or processed foods
  • DON’T eat more than three 80g portions of fresh fruit per day
  • DO get plenty of exercise
  • DON’T drink too much alcohol or fizzy drinks
  • DO try probiotics for a month to see if they help
  • DON’T drink more than three cups of tea or coffee a day
  • DO find ways to relax and look after your mental wellbeing
  • DON’T ignore IBS symptoms
  • DO keep a diary of what you eat and any symptoms you get to help identify triggers and understand what works for you.

Looking out for symptom triggers:

Consider keeping a food and symptom diary to help you monitor the foods you eat alongside when you experience symptoms. This can help spot patterns and potential trigger foods. You may also wish to include mood to this as there is close link between stress and IBS.

Some common triggers include:

  • Lactose: this is found in dairy products. So if you find your symptoms are worse after eating dairy products, trial lactose-free versions or dairy alternatives.
  • Wheat: this is a grain used to make bread, pasta, crackers, pastries, cakes, biscuits.
  • Gluten: this is a protein found in wheat, barley and rye.
  • A food additive or chemical such as caffeine, alcohol, artificial sweeteners.
  • Spicy foods.
  • Fatty foods.

Low FODMAP diet

If first line recommendations are unhelpful, it is usually a good idea to do blood test and stool sample to check for other potential conditions such as coeliac disease or inflammatory bowel disease. The low FODMAP diet can then also be tried.

This diet can be very labour intensive and time consuming so it is often viewed as a last resort. It is recommended to undertake this diet under the guidance of a dietitian as it can be very restrictive.

The aim of the low FODMAP diet is to eliminate foods containing carbohydrates called FODMAPs for 4-8 weeks to reduce symptoms. Then to gradually reintroduce foods to identify the precise triggers.

Please note that although many people find this diet helps reduce their symptoms, it does not work for everyone.

How is IBS diagnosed?

IBS can’t be diagnosed through laboratory or imaging tests. Instead, a doctor will perform a thorough exam and make a diagnosis based on your symptoms and medical history.

An important part of this is to rule out anything else that may be causing the symptoms, such as bowel cancer, coeliac disease or Crohn’s and Colitis.

Initial tests that the GP might conduct include:

  • a blood test to check for other conditions
  • a stool sample to check for infections and rule out inflammatory bowel disease (IBD)
  • a physical exam of the abdominal area to check for lumps or swelling.

They’ll also ask you questions about your symptoms, including how long you've had them, what they are, when you get them (for example, after eating certain foods), how often they arise and whether they come and go.

What should I do if I think I have IBS?

If you’re suffering with IBS symptoms, it’s worth keeping a diary where you can jot down details of your experiences. This will help you remember and keep track of everything, which is important when it comes to recognising patterns and ensuring you give your GP a detailed account of your experiences.

IBS symptoms can be connected to or caused by other serious conditions, so it’s important to see a GP if you’re experiencing any of the above symptoms on an ongoing basis. Particularly if you have acute abdominal pain, you’re losing a lot of weight, there’s blood in your stool or you have swelling in or around your stomach area.


  1. About IBS - IBS Facts and Statistics
  2. IBS - Diet, lifestyle and medicines - NHS