What IBS is
IBS is a long-term condition affecting how the gut works, with increased sensitivity of the bowel and changes in movement. Symptoms include abdominal pain related to bowel movements, bloating, wind, diarrhoea, constipation or both, and mucus. Symptoms come and go, often with stress and certain foods. IBS does not cause inflammation or damage, and it does not increase the risk of bowel cancer.
See IBS flare-up.
What IBD is
- Crohn’s disease: patchy inflammation that can affect any part of the digestive tract, often the end of the small intestine, through the full thickness of the bowel wall.
- Ulcerative colitis: continuous inflammation of the lining of the colon and rectum.
- Symptoms: diarrhoea, often with blood or mucus, abdominal pain, urgency, tiredness, weight loss and fever during flares.
- Outside the gut: joint pain, skin rashes, eye inflammation and mouth ulcers.
Key differences
- Inflammation: present in IBD; absent in IBS.
- Blood in stool: common in IBD, especially ulcerative colitis; not caused by IBS.
- Weight loss, fever and anaemia: point to IBD.
- Night-time diarrhoea: more typical of IBD.
- Test results: abnormal in IBD; normal in IBS.
- Complications: IBD can cause strictures, fistulas and increased colon cancer risk; IBS does not.
Can you have both?
Yes. Some people with IBD in remission still have IBS-like symptoms, such as pain and bloating without active inflammation. Distinguishing the two matters, because IBS-type symptoms do not need stronger IBD medicines.
How they are diagnosed
- Blood tests for anaemia, inflammation and coeliac disease.
- Stool calprotectin, a marker of gut inflammation, which is usually raised in IBD and normal in IBS.
- Stool tests for infection.
- Colonoscopy with biopsies to confirm IBD.
- Imaging such as MRI for Crohn’s disease of the small bowel.
IBS is diagnosed from typical symptoms once warning signs and other conditions have been ruled out.
Treatment of IBD
IBD is treated by gastroenterology teams with medicines such as aminosalicylates, steroids for flares, immunosuppressants and biologic or small-molecule therapies, and sometimes surgery. The aim is to control inflammation, achieve remission and prevent complications. Regular monitoring is important.
Treatment of IBS
- Regular meals and adjusting fibre.
- A low FODMAP diet with a dietitian; see low FODMAP diet for beginners.
- Peppermint oil and antispasmodics.
- Medicines for diarrhoea or constipation.
- Psychological therapies such as CBT and gut-directed hypnotherapy.
Diet in IBD
There is no single diet for IBD. During flares, some people tolerate low-residue, softer foods better, and people with strictures may need to avoid tough fibre. In remission, a varied, balanced diet is recommended. Malnutrition, iron, vitamin D and B12 deficiencies are common in IBD, so dietitian support is valuable. Exclusive enteral nutrition is used to induce remission in children with Crohn’s disease.
Diet in IBS
For IBS, identifying triggers through a food and symptom diary, eating regularly, limiting caffeine, alcohol and fizzy drinks and trying a supervised low FODMAP diet help many people.
See diet for IBS.
When each condition usually starts
IBS most often starts between the late teens and the 40s and is more common in women. IBD is usually diagnosed between 15 and 40, with a second smaller peak after 60, and affects men and women similarly. New bowel symptoms that start later in life, especially after 50, need investigation rather than an assumption of IBS.
Living well with either condition
- Keep a symptom diary to spot patterns and triggers.
- Do not cut out whole food groups without professional advice.
- Stay physically active, which helps bowel function, mood and fatigue.
- Seek support for anxiety or low mood, which are common in both.
- For IBD, attend regular reviews and keep vaccinations up to date.
- Plan ahead for travel and work, including toilet access.
Warning signs that need medical assessment
- Blood in the stool or black stools.
- Diarrhoea lasting more than 6 weeks or waking you at night.
- Unexplained weight loss.
- Fever, severe abdominal pain or vomiting.
- Anaemia or a family history of IBD or bowel cancer.
- New bowel symptoms after age 50.
Key points to remember
- IBD causes inflammation and damage; IBS does not.
- Blood, weight loss, fever and night symptoms point to IBD.
- Calprotectin and colonoscopy help tell them apart.
- Diet helps symptoms in both but does not replace IBD treatment.
Questions about IBD and IBS
These answers are general information and do not replace an examination or individual medical advice.
Is IBS a milder form of IBD?
No. They are different conditions, and IBS does not turn into IBD.
Can IBS cause blood in stool?
No. Blood in the stool needs medical assessment.
What is a calprotectin test?
A stool test that measures gut inflammation; it helps distinguish IBD from IBS.
Can stress cause IBD?
Stress does not cause IBD but can worsen symptoms.
Is a low FODMAP diet good for IBD?
It may help IBS-like symptoms in IBD remission, with dietitian guidance.
Does IBS increase cancer risk?
No. Long-standing colitis in IBD does slightly increase colon cancer risk.
Can you have IBS and IBD at the same time?
Yes, IBS-like symptoms are common in IBD remission.
Does IBS show up on a colonoscopy?
No. In IBS the bowel looks normal; in IBD inflammation is visible.
Is IBD curable?
There is no cure yet, but treatment can keep it in long-term remission.
Sources
- NHS · Irritable bowel syndrome (IBS)
- NHS · Inflammatory bowel disease (IBD)
- NHS · Crohn’s disease
- NHS · Ulcerative colitis
This guide is for general information and does not replace medical advice. How a problem is diagnosed and treated depends on your examination and medical history. If you think you have an emergency, contact your local emergency services.