Crohn's disease | Mate whēkau pauku

Also known as ileitis, inflammatory bowel disease, regional enteritis and granulomatous colitis

Key points about Crohn's disease (mate whēkau pauku) 

  • Crohn's disease is one of a group of conditions called inflammatory bowel disease (IBD).
  • It's a condition that causes swelling, thickening and inflammation of the gut. It's most likely to develop in your ileum (last part of your small intestine) or your colon.
  • The most common symptoms are abdominal pain and diarrhoea. 
  • Crohn's disease can occur at any age but is more common in young adults (18 to 35 years).
  • The exact cause of Crohn's disease is not well understood.
  • Treatments include medicines, nutrition supplements and sometimes surgery.
  • While the disease is life-long, some people have long periods of remission, when they are free of symptoms.
Woman holding abdomen in pain
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(Crohn's & Colitis UK, 2018)

The exact cause of Crohn's disease is unknown, but the following have been suggested:

Genetic factors (family history)

You're more likely to get Crohn's disease if a close family member has it. One in 4 people with Crohn's disease have a relative with Crohn's disease or ulcerative colitis. Recent research into how Crohn's disease runs in families has identified a human gene, called NOD2, which seems to play an important role in the interaction of the body's immune system with gut bacteria.

Immune system

Crohn’s disease may be due to a problem with your immune system (the body's defence against infection) that causes it to attack your digestive system. When your immune system tries to fight off infection caused by bacteria or viruses, an unusual immune response causes the immune system to attack the cells in the digestive tract.


It not exactly known how smoking is involved, but smoking makes you 3 to 4 times more likely to get Crohn's and smokers tend to have more aggressive disease.


There are no specific foods or a particular diet which cause Crohn's disease, however, there is emerging evidence that foods high in emulsifiers could lead to "leaky gut", which could trigger Crohn's. Emulsifiers are food additives used to mix together substances that would otherwise separate when they're combined, eg, oil and water. 

Everyone experiences Crohn’s differently. The symptoms of Crohn's disease depend on the location (where in the gut) and the spread (extent) of the swelling and inflammation in the gut. The symptoms can range from mild to severe.

The most common signs and symptoms are:

  • abdominal pain or stomach aches and cramps – most often in the lower-right part of your tummy (puku)
  • diarrhoea (having runny poo often, which may come on suddenly and you may need to reach a toilet quickly. You may have blood and mucus in your poo)
  • unintended weight loss.
  • tiredness (fatigue).

Other general signs and symptoms include:

  • a high temperature
  • feeling and being sick
  • joint pains
  • sore, red eyes
  • patches of painful, red and swollen skin – usually on your legs
  • mouth ulcers.

Children with Crohn's disease may grow more slowly than usual.

Symptoms can vary and depend on which part or parts of the gut are affected, for example:

  • If the disease is just in your small intestine, you may not have diarrhoea.
  • A persistent pain in your abdomen without any other symptoms may be due to a small patch of Crohn's disease in your small intestine.
  • A severe flare-up can make you generally very ill.
  • If large parts of your gut are affected, you may not absorb food well and you may become deficient in vitamins and other nutrients.

Crohn's disease is a chronic, relapsing condition. Chronic means that it's ongoing. Relapsing means that there are times when symptoms flare up (relapse) and times when there are few or no symptoms (remission). The severity of symptoms and how frequently they occur vary from person to person. The first episode (flare-up) of symptoms is often the worst.

Crohn's disease is diagnosed through taking a medical history, a physical examination, imaging tests to look at the intestines, and laboratory tests.

  • Your healthcare provider will ask about your medical history to identify any patterns, recent travel, family history of bowel disorders, and your medicines.
  • This is followed by examination and investigations, eg, blood tests (to look for inflammatory markers, anaemia, nutrient deficiencies) and stool (poo) samples (to look for infection, parasites and more).
  • A referral to a specialist is often needed for further assessment and additional tests such as colonoscopy and sometimes a CT scan or MRI scan.

The main aim of treatment for Crohn's disease is to stop inflammation in your gut, to prevent flare-ups and to keep you in remission. The kind of treatment depends on the type of symptoms and how bad they are.

If you have mild symptoms you may not need treatment as there's a chance that the symptoms will settle on their own. If your symptoms become worse, decisions about treatment can be reviewed.


Medicines are used to stop or control the inflammation in your gut and to prevent your body’s immune system from attacking itself. They aim to keep you symptom free or stop the disease from getting worse. The main groups of medicines to treat inflammation in Crohn’s disease are:

  • Steroids are used to treat sudden flare-ups and are not usually continued long-term after the flare-ups have settled.
  • Immunosuppressants are generally started when the disease isn't responding to steroids or is controlled only by having repeated courses of steroids. They may help you reduce or stop taking steroids without having another flare-up.
  • Biologics are used for people with severe Crohn’s disease, if they don't respond to other medicines, or if they have a fistula.

Read more about Medicines for Crohn’s disease.

Apps reviewed by Healthify

You may find it useful to look at some Digestive health apps and Nutrition, exercise and weight management apps.

Special diets

  • Children and young adults may be given a special liquid diet instead of eating and drinking usual food. This is also called exclusive enteral nutrition (EEN).
  • EEN can help them feel better by giving their gut a chance to rest and heal and should help them regain weight they have lost because of their condition.
  • It involves drinking a formula for a specific period – these products are easily digested and provide all the nutrients children need to grow properly.
  • Although EEN isn't used as often in adults, it can be an option for treating flare-ups when someone wants to avoid steroids.
  • Liquid only diets should only be used following medical advice, a dietitian will usually supervise this treatment.
  • Often children have EEN when they first receive a Crohn's disease diagnosis. They may also have EEN if they have a relapse. EEN works as well as medicines but has no side effects.


For some people, surgery may be considered. Surgery doesn't cure Crohn's disease but it's likely to provide relief from symptoms.

  • Surgery is sometimes necessary when your bowel keeps becoming blocked or when there are abscesses (swollen, infected areas) or small holes in your bowel wall.
  • Removal of the part of the bowel that is badly affected may relieve symptoms for a period of time but it doesn't cure the disease.
  • After surgery symptoms return (usually where the bowel has been joined), in 60 to 95% of cases. Further operation is required in nearly 50% of cases.
  • Surgery isn't performed unless there are specific complications or treatment with medicines hasn't provided relief. When operations have been performed, however, most people consider their quality of life has improved.
  • After surgery, you may be required to take long-term immunosuppressant drugs.

Read more about treatment and surgery options.(external link)

In managing Crohn's disease, it's very important to maintain a healthy lifestyle, even when the disease goes into remission (becomes symptom-free) for long periods of time. For example, if you smoke, quitting can help prevent symptoms from coming back. For people with Crohn’s disease, smoking is associated with worse disease and they are approximately 30% more likely to require surgery than non-smokers.

There is no single diet or foods that have been linked to Crohn's disease or symptoms recurring. If you suspect that something in your diet is a trigger, you can try a period of avoidance to see if symptoms improve. Overall it’s important to maintain a healthy, balanced diet. Ensure a regular intake of fruits and vegetables.

It's advisable to reduce your intake of:

  • saturated/trans fats
  • foods with high levels of emulsifiers
  • highly processed dairy
  • foods rich in maltodextrins (eg, salad dressings, canned soups, sports drinks)
  • foods with high levels of artificial sweeteners.

It's important to avoid unpasteurised dairy products where possible.

The outlook, or prognosis, for Crohn’s disease is different for different people. It  depends on which part or parts of your gut are affected and how often and how severe the flare-ups are.

Crohn's disease can range from being mild to very severe. Some people may experience only 1 episode and others (about 13–20% of people) may have ongoing episodes. This is called chronic Crohn’s disease.

  • Although recurrences tend to be normal, disease-free periods can last for years or decades for some people.
  • Although Crohn's disease can't be cured, even with surgery, treatments are now available that can help most people.
  • People with long-standing Crohn's disease of the small intestine carry an increased risk of small bowel cancer. Those with Crohn's colitis (Crohn's disease that is only found in the colon) have a long-term risk of colon cancer.

Video: Crohn's disease – Amanda's story

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(John Hopkins Medicine, US, 2019)

Video: Leaving Home - University with Crohn's and Colitis

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(Crohn's & Colitis UK, 2017)

Video: It Takes Guts to talk about Crohn's and Colitis

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(Crohn's & Colitis UK, 2019)

Video: Relationships with Crohn's disease

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(Crohn's & Colitis UK, 2017)

Video: Travelling with Crohn's and Colitis

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(Crohn's & Colitis UK, 2018)

Clinical pathways and resources

Inflammatory bowel disease – a focus on crohn's disease and ulcerative colitis(external link) BPAC, NZ, 2021
Crohn's disease – clinical pathway(external link) NICE, UK, 2012
Crohn's disease - clinical audit tools(external link) NICE, UK, 2012 
Crohn's disease – information for the public about the clinical pathway(external link) NICE, UK, 2012
Faecal calprotectin testing(external link) NICE, UK, 2013
Hospital admission rates for inflammatory bowel disease(external link) Southern Alliance, NZ

Continuing professional development

Goodfellow Unit Webinar: Inflammatory bowel disease | Tuesday 13 February 2018 | Dr Alasdair Patrick

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(Goodfellow Unit, NZ, 2018)


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Credits: Healthify editorial team. Healthify is brought to you by Health Navigator Charitable Trust.

Reviewed by: Dr Derek JY Luo, MBChB (Otago) FRACP, Consultant Gastroenterologist

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