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Crohn’s disease

Crohn's disease is an inflammatory bowel disease. It causes inflammation and ulcers in your digestive system, and can affect any part of your digestive tract from your mouth to your anus.

About Crohn's disease

Around one or two people in every 1,000 have Crohn’s disease. This means there are about 90,000 people in the UK with the condition.

Crohn's disease affects the wall of your bowel. It can affect any area from your mouth down through your stomach and bowel to your anus. However, it most commonly causes inflammation in the final part of your small bowel or the first part of your large bowel (colon). Crohn’s disease can affect more than one area of your bowel and leave areas in-between completely unaffected.

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

Crohn's disease is known as a ‘relapsing and remitting’ condition. This means that your symptoms can disappear and then flare-up again from time to time. Symptoms can be mild to severe. Crohn’s disease can settle down in one part of your bowel and then flare up in another part.

Crohn’s disease usually develops in teenagers and young adults, but it can be diagnosed at any age. It’s equally common in men and women. Your risk of developing Crohn’s disease is higher if other members of your family have the condition. Up to four in 10 people who have Crohn’s disease have a close relative who also has the condition.

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

Symptoms of Crohn's disease

Symptoms of Crohn’s disease can disappear and then flare up again from time to time. Sometimes it’s not clear what has caused it to flare up. You may have long periods with few or no symptoms at all.

Symptoms of Crohn's disease include:

  • frequent diarrhoea – sometimes with blood or mucus
  • pain in your abdomen (tummy)
  • weight loss
  • fever
  • tiredness

Crohn’s disease can also cause other problems, such as mouth ulcers, skin rashes, red and sore eyes or pain and swelling in your joints.

These symptoms aren’t always caused by Crohn’s disease but if you have them, see your GP.

Complications of Crohn's disease

If you have severe, long-term inflammation of your bowel, you may develop complications. Complications of Crohn’s disease are listed below.

  • A fissure. This is a tear in the wall of your anus which hurts and bleeds when you move your bowels.
  • A stricture in your bowel. Scar tissue can build up after inflammation and this can narrow and block your bowel.
  • An abscess. This is a collection of pus. If you develop a stricture this can cause a tear in the wall of your bowel. The contents of your bowel can leak through the tear and cause an abscess. This can then cause a fistula to develop.
  • A fistula. This is when the inflammation from your bowel spreads and causes an abnormal connection between your bowel and the surrounding tissues. A fistula can develop between two parts of your bowel, or between your bowel and other parts of your body such as your bladder, vagina or skin.
  • Malnutrition and anaemia. Damage to your bowel can affect how well your body is able to absorb vitamins and minerals from your food.
  • Bowel cancer. Crohn's disease increases your risk of developing bowel cancer. See our frequently asked questions for more information.

Causes of Crohn's disease

The exact reasons why you may develop Crohn's disease aren't fully understood at present. Researchers now think that Crohn’s disease is caused by a combination of factors. These include your genetics and the reaction of your immune system to certain bacteria or viruses in your bowel. Other factors, such as smoking, diet and stress may also play a part.

Diagnosis of Crohn's disease

Your GP will ask about your symptoms and examine you. He or she may ask for a sample of your faeces to check for a bacterial infection and do a blood test to check for anaemia and signs of inflammation.

You may be referred to a gastroenterologist (a doctor specialising in identifying and treating conditions of the digestive system) for more tests. These may include the following.

  • A gastroscopy to look inside your bowel. A narrow, flexible, tube-like telescopic camera, called an endoscope, is used to look inside your bowel and take samples of tissue for testing in the laboratory. You may have a colonoscopy to look inside your colon, or a flexible sigmoidoscopy to look inside your rectum (back passage) and lower part of your large bowel. For both of these tests the endoscope is put into your bowel through your rectum.
  • A barium swallow and meal or a barium enema X-ray. For a barium meal you will be asked to drink fluid containing barium (a substance that shows up on X-ray images). For a barium enema, fluid containing barium is put into your lower bowel through your rectum. X-ray images of your abdomen using barium show the inside of your bowel clearly.
  • CT scan or MRI scan to make a three-dimensional image of your abdomen. This is particularly useful to look for an abscess, which may not show up on the other X-rays.

Treatment of Crohn's disease

At the moment there is no cure for Crohn's disease. However, there are treatments that can help ease your symptoms and prevent complications. The treatment you have will depend on how severe your condition is. If your condition is very mild you may not need any treatment.


Eating a healthy, balanced diet is important for everyone, including if you have Crohn’s disease. You may find that you’re sensitive to certain foods which can make your symptoms worse. If this happens, then removing these foods from your diet can help. Always get advice from a dietitian before making any changes to your diet. See our frequently asked questions for more information.

During a flare-up, a liquid diet made up of simple forms of protein, carbohydrates and fats may help to ease your symptoms. These diets are called elemental or polymeric diets. You will need to follow them for three to six weeks. Because they are easier to digest they help rest your bowel, improve your nourishment and ease inflammation.


Medicines can help to prevent a flare-up or ease your symptoms during a flare-up of Crohn’s disease. You may need to go into hospital for treatment if the flare-up makes you too sick to be at home.

Your doctor may prescribe you a medicine called aminosalicylate (eg balsalazide, mesalazine or olsalazine) to help ease inflammation and reduce the chance of a flare-up. If you have a moderate flare-up, your doctor may increase the dose to try to control your symptoms, or prescribe other treatments to reduce inflammation. The main treatments are listed below.

  • Corticosteroids (such as hydrocortisone, beclometasone and budesonide). These are very effective but are usually used for a short time during a flare-up because they can cause you to gain weight and cause side-effects such as diabetes and osteoporosis.
  • Immunosuppressants (such as azathioprine, mercaptopurine and methotrexate) to suppress your immune system. These can increase your risk of infection.
  • Antibiotics to reduce risk of infection (such as metronidazole or ciprofloxacin).
  • Biological therapies (such as infliximab or adalimumab). These are usually only prescribed if your symptoms are severe.

If you need pain relief, you can take over-the-counter painkillers such as paracetamol. You shouldn't take non-steroidal anti-inflammatory medicines (NSAIDs), such as ibuprofen or aspirin. These can cause a flare-up of Crohn's disease. Always read the patient information leaflet that comes with your medicine and if you have any questions, ask your pharmacist or your doctor for advice. Painkillers will help with your symptoms but won’t affect how long a flare-up lasts, or how severe it is.


Your symptoms can usually be controlled with medicines. However, if you try a number of different treatments that don't work, or if you have complications, such as an abscess or fistula, your doctor may suggest surgery.

You can have an operation to remove a severely inflamed part of your bowel or to widen areas where it has narrowed because of a stricture. Even if all of your affected bowel is removed, the condition can return in your previously healthy bowel, so surgery isn’t a cure for Crohn’s disease.

Eight out of 10 people with Crohn's disease may need to have an operation at some point in their life. Some people may need several operations to treat Crohn’s disease.

Living with Crohn's disease

When your condition is in remission and you have few or no symptoms, then you will probably find that Crohn's disease has little impact on your day-to-day life. However, when you get a flare-up, your symptoms can make life more difficult. Frequent bouts of diarrhoea can make it harder to work. About one in 10 people who have had Crohn’s disease for longer than five years are unable to work.

Help and support

Being diagnosed with Crohn’s disease can be distressing. You may find it helpful to see a counsellor or join a support group to meet others in a similar situation.


Produced by Stephanie Hughes, Bupa Health Information Team, September 2012.

For answers to frequently asked questions on this topic, see FAQs.

For sources and links to further information, see Resources.

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  • This information was published by Bupa's Health Information Team and is based on reputable sources of medical evidence. It has been reviewed by appropriate medical or clinical professionals. Photos are only for illustrative purposes and do not reflect every presentation of a condition. The content is intended only for general information and does not replace the need for personal advice from a qualified health professional. For more details on how we produce our content and its sources, visit the about our health information page.

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