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Crohn's disease

Crohn's disease is an inflammatory bowel disease and can have both short and long-term effects. It causes symptoms such as diarrhoea and abdominal pain. Crohn's disease is a mild condition for some people, for others it may be severe.

About Crohn's disease

Crohn's disease is inflammation of the wall of your digestive system, from your mouth down through your stomach and bowel to your anus. However, it's most common in your small bowel or the first part of your large bowel. It may affect more than one area and leave unaffected areas in-between.

If you have Crohn's disease, you will have inflammation and swelling in affected areas of your bowel and ulcers may form. These are similar to mouth ulcers and cause raw areas of the lining of your bowel, which can bleed. Your bowel wall can become thickened and this may cause blockages.

Crohn's disease mostly affects young adults, although older people can also develop it. It can also run in families; about one in five people with the condition will have a family member who also has it.

Crohn's disease isn't caused by an infection and can't be caught from someone else.

The areas of the bowel commonly affected by Crohn's disease

Crohn's disease is a chronic illness. This means that it lasts for a long time, sometimes for the rest of the person's life. The term chronic refers to how long a person has the illness, not to how serious a condition is.

Symptoms of Crohn's disease

The symptoms of Crohn's disease can be unpredictable, with periods of time when the condition flares up, when the disease is said to be active, and periods of time when there are few or no symptoms at all. The period when you have no symptoms is called remission. Usually there's nothing obvious that triggers the symptoms coming back (a relapse).

Symptoms include:

  • diarrhoea - which may contain blood or mucus
  • painful abdomen (tummy) - this often happens around an hour after eating
  • weight loss
  • fever
  • tiredness
  • bleeding from your rectum (back passage) - this may lead to anaemia, a condition when there are too few red blood cells or not enough haemoglobin in your blood
  • broken skin, ulcers or abscesses (pus-filled areas) around your anus (if the anus is affected).

Active Crohn's disease may cause other problems such as:

  • mouth ulcers
  • joint pain
  • red, sore eyes
  • rashes.

Complications of Crohn's disease

With severe, long-term inflammation, you may develop complications. The main complications are:

  • a fistula. This is an abnormal connection between two parts of your body. In Crohn's disease, fistulas usually form between your bowel and your skin
  • an abscess in your abdomen. This is a collection of pus caused by an infection
  • a stricture. This can be caused by scar tissue that builds up after inflammation and may narrow and block your bowel.

If you have Crohn's disease that affects your colon, you will have a higher risk of developing bowel cancer. One in 20 people with Crohn's disease will develop bowel cancer in the 10 years after their condition is diagnosed.

Causes of Crohn's disease

The reasons why you may develop Crohn's disease aren't fully understood. It's thought that you're more likely to have Crohn's disease if you have a reaction between your immune system and certain bacteria in your bowel. For some people, Crohn's disease may be inherited and passed down through families.

There are certain lifestyle factors that make developing Crohn's disease more likely, for example, smoking. The role of certain foods isn't fully understood. However, it's possible that you're more likely to develop the condition if you eat only a small amount of fruit and vegetables.

Diagnosis of Crohn's disease

Your GP will ask about your symptoms and examine you. They may also ask you about your medical history. You may be referred to a gastroenterologist, a doctor who specialises in identifying and treating conditions of the digestive system. You may have a number of tests including:

  • blood tests
  • faeces (stool) tests
  • colonoscopy - this allows a doctor to look inside your large bowel
  • X-rays of your abdomen
  • Barium meal X-ray - this involves swallowing a drink containing barium (a substance which shows up on X-ray images) so the inside of your bowel can be seen more clearly
  • CT or MRI scan.

These tests usually take place as out-patient procedures. This means you have the test in hospital, but you won't need to stay overnight.

Treatment of Crohn's disease

There's no cure for Crohn's disease but your symptoms can be controlled.


There's no special diet for managing Crohn's disease but it's important that you eat healthy, balanced meals. However, if you have any blockages in your bowel which cause abdominal pain, you may want to eat foods that are low in fibre. This is called a low-residue diet. When your Crohn's disease is active, your doctor may recommend that you have a liquid diet, made up of simple forms of protein, carbohydrates and fats. This is called an elemental diet, and helps your bowel to rest and reduces inflammation.

Some people believe that fish oil supplements can help reduce the number of flare-ups of Crohn's disease, though this has not yet been proven.


Medicines are the most effective treatment for most people with Crohn's disease. Commonly used medicines are listed below.

  • Aminosalicylates, which are similar drugs to aspirin, treat milder inflammation or reduce the chances of a flare-up.
  • Corticosteroids, for example prednisolone, can help to reduce inflammation. These are very effective but can only be used for a short time during a flare-up because they can cause serious side-effects.
  • Medicines to suppress your immune system, for example mercaptopurine or azathioprine, can help to reduce inflammation once you've stopped taking corticosteroids.
  • Antibiotics, for example metronidazole, can help to reduce bacteria in your bowel or treat abscesses.

If you have severe Crohn's disease and have tried other treatments that haven't worked, your doctor may suggest medicines called tumour necrosis factor (TNF) inhibitors. Examples of these are infliximab and adalimumab.

If you need to take painkillers, avoid non-steroidal anti-inflammatory medicines (NSAIDs), such as ibuprofen. These can cause a flare-up of Crohn's disease. It's usually fine to take paracetamol as a painkiller, but check with your doctor first.


Eight out of 10 people with Crohn's disease may need to have an operation at some time. If you have a blockage or your bowel has become thickened, then you may need an operation to remove part of your bowel or to widen it. Surgery may also help if medicines aren't able to control your condition.

Living with Crohn's disease

When you're in remission with few or no symptoms, then you will probably find that Crohn's disease has little impact on your day-to-day life. However, when your condition flares up, your symptoms can make life more difficult. Symptoms such as diarrhoea and abdominal pain may mean you need to take time off work.

Once you start treatment for a flare-up, you should find that your symptoms will improve, usually after a few days or weeks.

Further information

Crohn's and Colitis Australia

Gastroenterological Society of Australia


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