Crohn's disease

Crohn's disease is a long-term condition that causes inflammation of the lining of the digestive system.

Inflammation can affect any part of the digestive system, from the mouth to the back passage. But it mostly occurs in the last section of the small intestine (ileum) or the large intestine (colon).

Crohn's disease can affect people of all ages, but it’s usually diagnosed between the age of 15 and 40.


The symptoms of Crohn's disease vary. They depend on which part of the digestive system is inflamed.

Common symptoms include:

  • recurring diarrhoea
  • abdominal pain and cramping, which is usually worse after eating
  • extreme tiredness (fatigue)
  • unintended weight loss
  • blood and mucus in your poo

You may have long periods without symptoms, or very mild symptoms. This is known as remission. This may be followed by periods where the symptoms are particularly troublesome. These are known as flare-ups or relapses.

Less common symptoms include:

  • a high temperature (fever) of 38°C (100°F) or above
  • feeling sick (nausea)
  • being sick (vomiting)
  • joint pain and swelling (arthritis)
  • inflammation and irritation of the eyes (uveitis)
  • areas of painful, red and swollen skin – most often the legs
  • mouth ulcers
  • anal pain and discharge due to perianal Crohn’s

Children with Crohn's disease may grow at a slower rate than expected.

Non-urgent advice: Speak to your GP practice if you have:

  • diarrhoea for more than 7 days
  • persistent abdominal pain
  • unexplained weight loss
  • blood in your poo
  • concern about your child's development


The exact cause of Crohn's disease is unknown.

A combination of factors may be responsible, including:

  • genetics – genes you inherit from your parents
  • a problem with the immune system (the body's defence against infection and illness) – where it attacks healthy bacteria in the gut and causes inflammation
  • environmental factors – like air pollution, medication or previous infections
  • smoking – smokers are twice as likely to develop Crohn's disease, and usually have more severe symptoms than non-smokers


Your GP will usually ask you about:

  • your pattern of symptoms
  • your diet
  • any recent travel – for example, you may have developed travellers' diarrhoea
  • whether you're taking any medication, including any over-the-counter medicines
  • whether anyone else in your family has any bowel conditions

Your GP may also carry out a tests to check your general health. For example, they may:

  • check your pulse
  • check your blood pressure
  • measure your height and weight
  • measure your temperature
  • examine your abdomen (tummy)

Your GP may also:

  • arrange blood tests to check for inflammation, infection and anaemia
  • ask for a stool (poo) sample to use a qFIT test to check for blood and mucus, infection or inflammation via a faecal calprotectin test

Referral to a specialist

You may be referred to a gastroenterologist. A gastroenterologist is a specialist in conditions of the digestive system. They might recommend more tests, such as:

  • gastroscopy – a thin flexible tube with a camera is put into your mouth to look at your food pipe and stomach
  • colonoscopy – a thin, flexible tube with a camera is put into your bottom to look at the whole of your large bowel
  • sigmoidoscopy – a thin, flexible tube with a camera is put into your bottom to look at the end of your large bowel
  • a colon capsule endoscopy (pill camera)
  • X-ray or barium enema
  • MRI scan or CT scan

You will be told what tests you need and what you need to do to prepare for them.


There's currently no cure for Crohn's disease, but treatment can improve the symptoms and keep the inflammation under control.

Your treatment will usually be provided by a range of healthcare professionals.

Once your symptoms are under control, you are likely to be offered treatment to help keep them under control. If your Crohn's stays under control for a long time, you may choose to stop treatment. You may need to start again if your symptoms come back.

Steroid medication

The first treatment offered is usually steroids, such as prednisolone or budesonide (corticosteroids) to reduce inflammation quickly. Steroids are often effective in reducing your symptoms. But they can have significant side effects. So they’re not suitable for long-term use and your dose will slowly be reduced when your symptoms start to improve.

Medicines to suppress your immune system

Medicines to suppress your immune system (immunosuppressants) may be given alongside steroids if your symptoms flare up twice or more during 12 months, or return when your steroid dose is reduced.

Common types include azathioprine, mercaptopurine and methotrexate.

Biological therapies

If steroids and immunosuppressants don't help or aren't right for you, biological therapies may be used.

Biological therapies block particular chemicals involved in the immune response, which helps reduce inflammation. They're made using living cells in a lab. They can be given as a drip or an injection. Treatment usually lasts at least 12 months. Your inflammatory bowel disease (IBD) team will be able to discuss these with you.

Common types are adalimumab, infliximab, ustekinumab or vedolizumab.

There's a risk that these medicines may cause side effects, which can cause symptoms such as:

  • itchy skin
  • a high temperature
  • joint and muscle pain
  • swelling of the hands or lips
  • problems swallowing

You should seek immediate medical help if you experience these symptoms. Reactions can occur immediately after treatment or months later, even after treatment stops.


Surgery to treat Crohn’s disease may be an option if:

  • you choose to have surgery instead of taking medications that may cause side effects
  • medications don't control your symptoms
  • your quality of life is severely affected by your condition
  • you have serious complications of Crohn’s disease

Surgery might involve widening narrow parts of your bowel, or removing parts of it (resection).

Resection involves removing the inflamed area of the intestine.

If you have a resection, you might have the healthy sections of bowel joined back together. Or you might have the end of your small bowel joined to the skin of your tummy (an ileostomy or stoma). In this case, poo comes out of the opening on your tummy and is collected in special bags that you wear. An ileostomy might be temporary, to give your bowel time to heal, or it might be permanent.

Your IBD team will tell you what surgery they recommend and let you know what to expect.

Diet and smoking

There's no evidence that any particular diet triggers flare-ups in Crohn's disease. But some people have found certain foods make their symptoms worse and have found nutritional treatments can help. You may find it useful to keep a food diary. You can record the foods you eat and the effects they have on your symptoms.

If you notice certain foods make your symptoms worse, avoiding these may reduce your symptoms. But removing entire food groups from your diets isn't usually recommended because you may miss out on essential nutrients. Speak to your GP or IBD team before making any big changes to your diet.

Some people find it helpful to eat 6 smaller meals a day rather than 3 larger meals.

If you smoke, smoking can make Crohn’s worse and is it important that you make every effort to stop smoking.

Fertility and pregnancy

A woman's chance of becoming pregnant isn't usually affected by Crohn’s disease.

However, surgery for Crohn’s disease might affect your fertility.

Most women with Crohn’s disease will have a normal pregnancy and a healthy baby. But if you're pregnant or planning a pregnancy you should discuss it with your IBD team. This is because they may need to change your medication.

If you're having a flare-up of Crohn’s disease you may also be advised to avoid getting pregnant until it's under control.


Over time, inflammation can damage sections of the digestive system. This can result in complications such as:

  • narrowing of the bowel (stricture)
  • a channel developing between your bowel and your skin, another section of bowel or a body organ (fistula)

These problems usually need surgical treatment.

Information about you

If you have Crohn's disease, your clinical team will pass information about you on to the National Congenital Anomaly and Rare Diseases Registration Service (NCARDRS).

This helps scientists look for better ways to prevent and treat this condition. You can opt out of the register at any time.

Find out more about the register

Last updated:
24 March 2023