Inflammatory Bowel Disease (Crohn’s and Colitis)
Two long-term conditions, Crohn’s disease and ulcerative colitis, where the immune system inflames the gut. They come and go in flares. Treatment has improved hugely, and most people lead full lives.
Quick answer: Inflammatory bowel disease (IBD) means Crohn’s disease or ulcerative colitis: long-term gut inflammation causing diarrhoea (often bloody), tummy pain, urgency, weight loss and tiredness. It’s different from IBS. Diagnosis uses faecal calprotectin, blood tests and colonoscopy with biopsies. Treatments include mesalazine, steroids, immunosuppressants and biologics; the aim is lasting remission.
How common. Australia has one of the highest rates in the world: nearly 180,000 Australians live with IBD. It usually starts between 15 and 30, with a smaller peak later in life, and affects men and women about equally.
Crohn’s vs ulcerative colitis. Crohn’s disease can affect any part of the gut from mouth to anus, in patches, through the full thickness of the bowel wall; it can cause narrowing, abscesses and fistulas, especially around the anus. Ulcerative colitis affects only the large bowel (colon and rectum), continuously from the rectum upwards, in the lining. About 1 in 10 can’t be classified at first.
Causes. An overactive immune response to gut bacteria in people with a genetic tendency, shaped by environment. Smoking roughly doubles the risk of Crohn’s and makes it worse. It isn’t caused by stress or diet, though both can affect symptoms.
Symptoms. Diarrhoea lasting more than a few weeks, blood or mucus in the poo (especially in colitis), urgency, tummy pain and cramping, tiredness, weight loss, fevers and anaemia. Crohn’s can cause painful sores or discharge near the anus and mouth ulcers. Children may grow slowly. Up to about 1 in 3 have symptoms outside the gut: joint pain, red eyes, tender shin lumps (erythema nodosum), skin ulcers, and liver and bile duct inflammation.
Look-alikes. IBS (no inflammation or bleeding), gut infections, coeliac disease, medicine side effects, bowel cancer and, rarely, Behçet’s disease, which can cause similar gut ulcers.
How it’s diagnosed. Your GP checks blood tests (blood count, iron, inflammation markers, coeliac antibodies), a stool test for infection, and faecal calprotectin, which NICE recommends to help tell IBD from IBS: a normal result makes IBD unlikely. A colonoscopy with biopsies confirms it. MRI or CT and capsule endoscopy look at the small bowel in Crohn’s. Disease extent is described using the Montreal classification.
Treatment
The aim is remission: no symptoms and a healed bowel lining. Plans follow BSG 2025, ECCO and NICE guidelines, made with your gastroenterologist.
- Everyone · Self-careStop smoking, eat well, keep vaccinations up to dateQuitting is one of the most effective things you can do for Crohn’s. A dietitian can help in flares or with narrowing.
- Works
- Quitting smoking lowers flares and surgery in Crohn’s
- Access
- Quit aids are PBS-subsidised
- Watch for
- Avoid anti-inflammatory painkillers (NSAIDs) if you can; they can trigger flares.
- Mild to moderate colitis · PrescriptionMesalazine (a 5-ASA)Tablets, granules, suppositories or enemas. Used to bring on and keep remission in ulcerative colitis.
- Works
- Induces and maintains remission in mild to moderate colitis; much less useful in Crohn’s
- Access
- PBS-subsidised
- Watch for
- Headache and nausea; rarely kidney effects, so yearly kidney tests.
- Flares · PrescriptionCorticosteroidsPrednisolone, or budesonide for some types, to settle a flare over weeks, then tapered off. In children with Crohn’s, exclusive liquid nutrition is a steroid-free alternative.
- Works
- Bring most flares under control
- Access
- PBS-subsidised
- Watch for
- Not for long-term use; needing them twice a year means stepping up treatment.
- Keeping remission · SpecialistThiopurines (azathioprine) or methotrexateSteroid-sparing medicines to keep remission.
- Works
- Reduce flares and steroid use
- Access
- Specialist-guided; PBS-subsidised
- Watch for
- Regular blood tests; slightly higher risk of skin cancer and lymphoma with thiopurines.
- Moderate to severe · SpecialistBiologics and small moleculesInfliximab, adalimumab, vedolizumab, ustekinumab and others by infusion or injection; tablets such as tofacitinib, upadacitinib or ozanimod.
- Works
- Induce and maintain remission in many people who haven’t responded to other treatment, and lower surgery and hospital stays
- Access
- Specialist only; PBS-subsidised in Australia with criteria
- Watch for
- Infection risk, including TB reactivation; screening first.
- When needed · SurgeryBowel surgeryRemoving a damaged section in Crohn’s, or the colon in severe colitis (sometimes with an internal pouch).
- Works
- Can be life-changing; removing the colon cures the bowel part of ulcerative colitis
- Access
- Public or private surgery
- Watch for
- Crohn’s can come back near the join, so medicines often continue.
Save your money
Popular, heavily marketed or often asked about, but the evidence is weak or says no.
- ’Leaky gut’ tests and curesIBD needs proper medical treatment. Supplements and ’gut healing’ programs haven’t been shown to induce remission, and delaying treatment risks complications.
- Probiotics for Crohn’sNo good evidence they help Crohn’s. One specific multi-strain probiotic may help pouchitis after surgery; ask your team.
Living with it
- Take maintenance medicines even when well; most flares follow stopping them.
- Get flu, COVID-19 and pneumococcal vaccines, and avoid live vaccines on some treatments (ask first).
- Have bowel cancer surveillance colonoscopies, usually starting about 8 years after symptoms began in colitis or Crohn’s of the colon.
- Watch for iron deficiency, low vitamin D and B12, and bone thinning.
- Plan pregnancy with your team: most IBD medicines are safe, and quiet disease matters most.
- In Australia, Crohn’s & Colitis Australia offers support and information.
See your GP if
- Diarrhoea lasts more than 4 weeks, or comes with blood, weight loss or night-time symptoms
- You have ongoing tummy pain with tiredness, fevers or mouth ulcers
- You have pain, a lump or discharge near your anus
- You have IBD and symptoms are flaring or you’re needing steroids often
Get urgent help for 6 or more bloody poos a day with fever, a racing heart or feeling faint; severe tummy pain or a swollen, tender tummy; vomiting with no poo or wind; or heavy bleeding: call 000 (Australia) or your local emergency number or go to an emergency department. Severe colitis needs hospital treatment.
Outlook. IBD is lifelong but very treatable. Most people have long periods of remission and normal life expectancy. Surgery is less common than in the past thanks to earlier and better treatment. World IBD Day is on 19 May: see our health days calendar.
Common questions
What is the difference between Crohn’s disease and ulcerative colitis?
Crohn’s can affect any part of the gut, in patches and through the full bowel wall. Ulcerative colitis affects only the large bowel, continuously from the rectum, in the lining.
Is IBD the same as IBS?
No. IBD (Crohn’s and colitis) causes visible inflammation and damage to the bowel. IBS causes real symptoms but without inflammation. A faecal calprotectin test helps tell them apart.
What are the early signs of Crohn’s disease?
Ongoing diarrhoea, tummy pain, tiredness, weight loss, mouth ulcers, and sometimes pain or discharge around the anus. Children may grow slowly.
What does calprotectin show?
Calprotectin is a protein released by inflamed gut lining. A normal result makes IBD unlikely; a raised result needs further tests such as colonoscopy.
Can inflammatory bowel disease be cured?
Not yet with medicines, but most people achieve long-term remission. Removing the colon cures the bowel disease in ulcerative colitis, though it’s a big decision.
What foods should you avoid with IBD?
No single diet suits everyone. During flares or with narrowing, low-fibre foods may help. Keep a food diary and see a dietitian rather than cutting out whole food groups.
Does IBD increase the risk of bowel cancer?
Long-standing colitis or Crohn’s affecting the colon slightly raises the risk, which is why regular surveillance colonoscopies are offered.
Evidence and more information
- Moran et al, BSG 2025: Guidelines on inflammatory bowel disease in adults
- NICE DG11: Faecal calprotectin diagnostic tests for inflammatory diseases of the bowel
- NICE NG129: Crohn’s disease management
- NICE NG130: Ulcerative colitis management
- Crohn’s & Colitis Australia: State of the Nation in IBD summary report (2025)
- NHS: Inflammatory bowel disease
maladywise.com/inflammatory-bowel-disease/