Written by James McIntosh
Reviewed by Sammie Gill
‘IBS’ stands for irritable bowel syndrome, while ‘IBD’ is inflammatory bowel disease.
Both health conditions affect the gut, and they share some symptoms. And while their acronyms are similar, IBS and IBD are very different conditions.
The most common forms of IBD are Crohn’s disease and ulcerative colitis. These conditions are characterised by inflammation in the gut that’s driven by the immune system.
All together, the forms of IBD affect around 1% of people in the United Kingdom.
IBS, on the other hand, is a ‘syndrome’ because it’s a collection of symptoms without a clear cause. It affects an estimated 5–10% of people in the UK.
Medical tests can help diagnose IBD, whereas doctors diagnose IBS by considering your symptoms and ruling out other conditions, such as coeliac disease.
Another difference is that IBD increases the risk of developing colon cancer, but IBS doesn’t.
Some people have both IBS and IBD, but one can’t turn into the other. Below, we’ll dive into the differences in symptoms, risk factors, causes and treatments.
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Comparing IBS and IBD symptoms
Both IBS and IBD affect the oesophagus (food pipe), stomach and intestines. While some symptoms overlap, others are distinct.
It’s important to note: IBS and IBD symptoms can differ significantly from person to person. And in each person, the symptoms may change over time.
IBS symptoms
These typically include:
- abdominal pain and cramps (often after eating), which tend to improve after a poo
- changes in poo habits: diarrhoea, constipation or both, and possibly incontinence
- bloating and excess wind
- passing mucus from your bum
Other symptoms
- back pain
- nausea
- fatigue
IBD symptoms
These often include:
- abdominal pain
- changes in poo habits, including diarrhoea and constipation
- blood or mucus in stool
- unexpected weight loss
Other symptoms
- fatigue
- low-grade fever
- joint pain
- nausea and vomiting
- mouth sores or ulcers
- skin problems
Over time, IBD causes damage to the gut, whereas IBS doesn’t.
What can make matters confusing is that around 35–40% of people with IBD have IBS-type symptoms.
Risk factors and causes of IBS and IBD
IBD results from inflammation, which can cause permanent damage to the gut, sometimes requiring hospitalisation or surgery.
IBS, however, is considered a disorder of the gut-brain connection and rarely requires hospital care.
The underlying causes of both conditions remain mysterious, scientists are still working to understand why some people develop IBD or IBS while others don’t.
IBS risk factors and causes
So far, research suggests that these factors are linked to an increased risk of developing IBS:
- being female
- smoking
- frequent alcohol consumption
- psychological stress
- mental health conditions
- gastroenteritis (a tummy bug)
- pain disorders, like fibromyalgia
- sleep disorders
- antibiotic use
Also, certain medications, like antidepressants and hormone replacement therapy (HRT), may increase the risk.
Interestingly, older adults seem less likely to develop IBS than younger adults, though not all studies agree.
IBD risk factors and causes
Scientists are still figuring out what makes some people more susceptible to IBD, but there’s likely a genetic component.
So, if you have a first-degree relative with IBD, you have an increased risk of developing it.
In the absence of more solid answers, here are some factors that scientists have investigated:
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Smoking: This is linked with an increased risk of developing IBD (and gut-related cancers).
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Early life exposures: Bed sharing, having siblings, and being around pets and farm animals are all linked to a lower risk of IBD.
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Infection: Certain bacteria, like some species of Salmonella and Campylobacter, as well as the bacterium Clostridium difficile (C. diff), may increase the risk of developing IBD.
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Drugs: Some medications may increase your IBD risk, such as non-steroidal anti-inflammatory drugs (NSAIDs) and antibiotics.
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The Western diet: A diet high in ultra-processed foods, sugar and saturated fat may increase your risk. Also, consuming additives, like emulsifiers, may contribute to the development of IBD. The Mediterranean diet, however, may reduce your risk.
- Mental health conditions: Depression and anxiety may relate to IBD. However, scientists are still unsure if these conditions can play a role in the development of IBD or arise as a consequence of IBD.
At this point, not all studies agree. Arriving at a conclusive list of risk factors will require more research.
Treating IBS and IBD
Taking medications and making lifestyle changes can help manage the symptoms of both IBS and IBD, but currently, neither condition can be cured.
Treatments for IBS
Depending on your symptoms, a doctor might suggest:
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Dietary changes: This might mean gradually boosting your fibre intake and avoiding certain triggers, which may include dairy, spices, fatty foods and caffeine. The doctor might also recommend a low-FODMAP diet.
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Lifestyle changes: These might include incorporating more movement into your days, reducing stress and getting more sleep.
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Medications for symptoms: The options will depend on whether you mostly experience diarrhoea or constipation.
- Medications for pain: If you have abdominal pain, for example, the doctor may recommend peppermint oil capsules or an antispasmodic drug, which relaxes the muscles of your gut wall.
Treatments for IBD
Many medications can effectively control the symptoms of IBD.
But these have limitations, including side effects. And for some people, these drugs don’t work or gradually become less effective.
Luckily, over the last 10 years, there have been major advances in IBD management, with emerging novel therapies and complementary therapies, like probiotics, prebiotics, synbiotics and poo transplants.
Some available drugs include:
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Immunosuppressants: These help stop the immune system from attacking the gut.
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Aminosalicylates (5-ASAs): These reduce inflammation.
- Drugs to treat symptoms: This might reduce pain, nausea, diarrhoea, excess gas or stomach cramps.
For some people, doctors recommend surgery. Often, these procedures are performed through a small opening in the abdomen, an approach called keyhole surgery.
Surgery for Crohn’s can include:
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Strictureplasty: This widens the intestines to allow food to pass more easily.
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Bowel resection: This removes a damaged section of the colon. Some people who undergo it require a stoma – a small opening in the abdomen through which poo is transferred into a collection bag.
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Surgery for abscesses: These are painful collections of bacteria and pus.
- Surgery for fistulas: These are tunnels (caused by ulcers) that form between your gut and other organs.
Surgery for ulcerative colitis can include:
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Ileostomy surgery: This involves creating a stoma.
- Pouch surgery: This involves removing the colon and rectum. The surgeon creates a pouch from the end of the small intestine (the ileum). Then, usually in a second procedure, they connect the pouch to the person’s anus. This allows the person to poo in a regular way without needing a stoma.
What to do if you think you have IBD or IBS
If you believe that you have either condition, speak with your doctor. They can assess your symptoms and recommend effective treatments and lifestyle changes.
It's important to get the correct diagnosis to manage your symptoms well in the long term.
Your doctor may arrange a blood test and a poo test as a first step.
Summary
Both IBS and IBD affect your gut and can significantly impact your quality of life.
IBD is characterised by an immune response and inflammation that damages your gut. So far, the causes of IBS are less clear.
Many approaches, including dietary and lifestyle changes, can improve the symptoms and your quality of life.
Doctors treat IBD with drugs that suppress the immune system and control inflammation. Surgery might also be necessary.
For people with IBS, the doctor may prescribe laxatives, anti-motility medications or antispasmodic drugs.
To learn more about other gut health topics, visit Symprove’s Gut Hub.
Sources
Adherence to a Mediterranean diet is associated with a lower risk of later-onset Crohn’s disease: Results from two large prospective cohort studies. Gut. (2019). Link.
British Society of Gastroenterology consensus guidelines on the management of inflammatory bowel disease in adults. Gut. (2019). Link.
Genetics and epigenetics of IBD. Pharmacological Research. (2020). Link.
Horizon scanning: New and future therapies in the management of inflammatory bowel disease. eGastroenterology. (2023). Link.
Inflammatory bowel disease (IBD). (2023). Link.
Irritable bowel syndrome (IBS). (2021). Link.
Overlap between irritable bowel syndrome and inflammatory bowel disease. Gastroenterology and Hepatology. (2020). Link.
Prevalence and risk factors of irritable bowel syndrome in healthy screenee undergoing colonoscopy and laboratory tests. Journal of Neurogastroenterology and Motility. (2010). Link.
Psychological factors associated with inflammatory bowel disease. British Medical Bulletin. (2019). Link.
Review article: The incidence and risk factors for irritable bowel syndrome in population-based studies. Alimentary Pharmacology and Therapeutics. (2019). Link.
Surgery for Crohn's disease. (2022). Link.
Surgery for ulcerative colitis. (2022). Link.
The epidemiology and risk factors of inflammatory bowel disease. International Journal of Clinical and Experimental Medicine. (2015). Link.
Treatment for irritable bowel syndrome. (2017). Link.
Treatments. (n.d.). Link.
