Crohn's disease is a chronic inflammatory condition of the gastrointestinal (GI) tract and one of the two main types of inflammatory bowel disease (IBD), alongside ulcerative colitis. Unlike ulcerative colitis, which is confined to the colon and rectum, Crohn's disease can affect any part of the GI tract from the mouth to the anus – most commonly the end of the small intestine (the terminal ileum) and the beginning of the large intestine.
Crohn's disease is characterised by periods of flare, when symptoms are active, and periods of remission, when symptoms ease or resolve. There is no cure, but with the right treatment many people are able to achieve and maintain long-term remission.
How common is Crohn's Disease?
Australia has one of the highest rates of Crohn's disease in the world. Approximately 85,000 Australians are estimated to be living with Crohn's disease, with around 5,000 new diagnoses each year. It can develop at any age but is most commonly diagnosed in people aged 15 to 35. Crohn's disease affects men and women in roughly equal numbers.
Symptoms vary depending on which part of the GI tract is affected and the severity of inflammation.
Common symptoms include:
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- Persistent diarrhoea, which may be watery or bloody
- Abdominal pain and cramping, often in the lower right area
- Fatigue and low energy
- Unintended weight loss and reduced appetite
- Nausea and vomiting
- Fever during active flares
- Urgency to open the bowels
Crohn's disease can also cause complications outside the gut (extraintestinal manifestations), including joint pain, skin rashes, eye inflammation, and mouth ulcers.
Complications within the gut – such as strictures (narrowing), fistulas (abnormal connections between organs), and abscesses – can develop in more severe or longstanding disease.
The exact cause is not fully understood. Crohn's disease is thought to result from an abnormal immune response in which the gut's immune system attacks the lining of the GI tract, likely triggered by a combination of:
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- Genetics – Crohn's disease runs in families; having a first-degree relative with IBD significantly increases risk
- Immune system dysfunction – an overactive or dysregulated immune response to gut bacteria appears central to the condition
- Environmental factors – including diet, antibiotic use, and changes in gut microbiome. Smoking significantly worsens Crohn's disease outcomes
- Gut microbiome – imbalances in the bacteria that normally live in the gut are thought to play a role
Crohn's disease is more common in urban, industrialised settings, and its incidence has been rising in Australia and globally.
There is no single test for Crohn's disease.
Diagnosis involves a combination of:
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- Colonoscopy and biopsy – the most important diagnostic tool; allows direct visualisation of the bowel lining and collection of tissue samples
- Gastroscopy – to assess the upper GI tract if involvement is suspected
- Blood tests – including inflammatory markers (CRP, ESR), full blood count, and nutritional assessments (iron, B12, folate, vitamin D)
- Stool tests – including faecal calprotectin, a marker of gut inflammation, and tests to rule out infectious causes of diarrhoea
- Imaging – MRI enterography or CT enterography to assess the small bowel and identify complications such as strictures, fistulas, or abscesses
Treatment aims to induce and maintain remission, heal the bowel lining (mucosal healing), and prevent complications. The approach depends on disease location, severity, and individual factors.
Induction of remission
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- Corticosteroids – such as prednisolone or budesonide, are used to quickly control active inflammation. Not suitable for long-term use due to side effects
- Exclusive enteral nutrition (EEN) – a liquid-only diet administered via a tube or orally; a first-line option for inducing remission in children and adolescents, and sometimes used in adults
- Biologic therapies – for moderate to severe disease, biologics such as adalimumab and infliximab are increasingly used as primary induction agents
Maintenance of remission
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- Immunomodulators – azathioprine and mercaptopurine are used to maintain remission and reduce reliance on corticosteroids. Methotrexate is used when these are not tolerated
- Biologic therapies – target specific parts of the immune system and are used when conventional treatments haven't provided adequate control. Options include TNF inhibitors (adalimumab, infliximab), anti-integrins (vedolizumab), IL-12/23 inhibitors (ustekinumab), and IL-23 inhibitors (risankizumab).
- JAK inhibitors – (Janus kinase inhibitors) are a newer class of oral medications used when other treatments have been insufficient. Upadacitinib is an option for adults with Crohn's disease who have not responded to conventional therapies.
- Surgery – may be required for complications such as strictures, fistulas, or bowel perforation. Surgery is not curative in Crohn's disease as inflammation can recur elsewhere in the GI tract
Regular monitoring – including colonoscopy, inflammatory markers, and therapeutic drug monitoring for biologic medications – is an important part of ongoing management.
The following specialty medications are available at Ace, a specialty pharmacy for Crohn's Disease.
Biosimilars of adalimumab and infliximab are available. Speak with your Ace pharmacist about your options.
With Ace, you’ll benefit from:
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- Expert Support — Our dedicated team of health concierges is always available to answer your questions, provide guidance, and help you navigate your condition with confidence.
- Specialty Medication — We offer a wide range of specialty medications and support services, designed specifically for those living with chronic illnesses. Whether you’re looking for help managing a specific condition, or simply need access to the medications you need, we’ve got you covered.
- A Wide Range of Conditions — From diabetes to heart disease, and everything in between, we help manage a variety of special condition
Take control of your health and well-being, and start your journey to better health with Ace today.
IBD-Specific Support
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- Crohn's and Colitis Australia (CCA) – Australia's peak patient organisation for IBD; information, peer support, nurse helpline, and local support groups
- CCA – Nurse Helpline – 1800 CCA IBD (1800 222 423)
- CCA – Find a Doctor
Clinical & Research Resources
