Navigation

Crohn’s disease

Expert reviewer, Dr Ian Arnott, Consultant Gastroenterologist and Dr Ade Adeniyi, General Practitioner
Next review due September 2024

Crohn’s disease is a lifelong inflammatory bowel disease (IBD). It can affect any part of your digestive system, and cause tummy pain, persistent diarrhoea and ulcers. Crohn’s disease is one of the two major types of IBD – the other is ulcerative colitis.


Image showing the digestive system

About Crohn's disease

Crohn’s disease can affect any part of your digestive system – from your mouth to your anus (back passage). But it most often causes inflammation in the final part of your small bowel (ileum) and the large bowel (colon). The inflamed areas are usually separated by healthy areas of bowel called skip lesions. Crohn's Disease affects about one in every 650 people in the UK.

If you have Crohn's disease, you’ll probably have times when your symptoms flare up and other times when they go away. Some people have mild Crohn’s disease and occasional symptoms; others have severe symptoms that affect all aspects of life. Some people find it hard to cope, which can lead to depression or anxiety.

Causes of Crohn's disease

Doctors don’t know exactly why some people get Crohn’s disease and others don’t. But it’s thought that several things can trigger the condition in susceptible people.

  • You’re more likely to have Crohn’s disease if it runs in your family. If you’ve inherited the genes for Crohn’s disease, you may be more likely to get the condition if you come into contact with certain triggers.
  • You’re more likely to have Crohn’s disease if you smoke. Smoking also makes you more likely to have regular flare-ups and more likely to need surgery to treat Crohn’s disease.
  • Your immune system may react abnormally to certain bacteria or viruses in your bowel, which causes inflammation. Some people develop Crohn’s disease after they’ve had gastroenteritis. Crohn’s disease has also been linked to changes in the types and numbers of bacteria that live naturally in your digestive system.
  • You may be more likely to have flare ups of Crohn’s disease if you regularly take non-steroidal anti-inflammatory drugs such as ibuprofen.
  • If you eat a lot of processed foods, it may increase your chance of getting Crohn’s disease.

Symptoms of Crohn's disease

Crohn's disease symptoms may vary from mild to really severe. They may change over time with flare-ups and calm periods. Some people don’t have specific digestive symptoms, so they’re not diagnosed with Crohn’s disease for many years.

The main symptoms and signs of Crohn's disease include:

  • diarrhoea that doesn’t get better – sometimes it contains blood or mucus
  • pain in your tummy, which can be severe
  • feeling extremely tired
  • losing weight for no reason
  • a fever
  • feeling generally unwell
  • feeling or being sick (nausea and vomiting)

Crohn’s disease can also affect other parts of your body. You may have:

  • mouth ulcers
  • red and sore eyes
  • a rash on your skin
  • pain and swelling in your joints

If you have any of these symptoms, see your GP.

Diagnosis of Crohn's disease

Your GP will ask about your symptoms and examine you. They’ll also ask about your medical and family history. They may ask for a sample of your poo to check if you have a bacterial infection and may also check for a substance called faecal calprotectin. If you have high levels of this in your poo, you may have inflammation in your bowel, possibly caused by Crohn’s disease.

Your GP will also take a blood sample to check your iron levels to see if you have anaemia, and to look for other signs of inflammation.

If you’re very unwell with diarrhoea, bloody poo, a fever, fast heart rate or low blood pressure, your GP will refer you to hospital immediately. Otherwise, your GP may refer you to a specialist inflammatory bowel disease (IBD) team for more tests. These tests may include the following.

  • A colonoscopy to look inside your bowel and take tissue samples.
  • A CT scan or MRI scan to create images of the inside of your tummy. You may need to drink a liquid called contrast medium to help make your small bowel show up more clearly.
  • A capsule endoscopy, in which you swallow a small capsule that contains a tiny video camera. As it passes through your small bowel, the camera takes digital pictures that are recorded and viewed on a screen by your doctor.

Self-help for Crohn's disease

There are things you can do to help ease the symptoms of Crohn’s disease. For example, it’s really worth trying to stop smoking because this may make you less likely to have flare-ups. Ask your pharmacist about how to quit smoking.

Diet and Crohn’s disease

If you have Crohn’s disease, it's important to eat a healthy, balanced diet to make sure you get all the nutrients you need. There isn’t any specific diet for Crohn’s’ disease.

You may find it helpful to keep a food diary to see if anything in particular triggers your symptoms. Click to open a PDF version of Bupa's food and symptoms diary (PDF, 1.4MB). Certain foods –for example, those high in fibre – can sometimes make your symptoms worse. If you think some foods make your Crohn’s disease worse, do speak to a dietitian before you stop eating them. Otherwise, you could miss out on essential nutrients.

Your doctor may recommend a liquid diet (enteral diet) during a flare-up to ease your symptoms. Liquid diets are easier to digest than normal food and will give you all of the essential nutrients you need. As well as providing the nutrients you need, they help to ease any inflammation in your digestive system.

Treatment of Crohn's disease

There isn’t a cure for Crohn's disease, but different treatments can help to ease your symptoms and stop them coming back. Crohn’s disease is a lifelong condition that flares up and calms down.

It’s important to keep Crohn's disease under control because this will help to prevent complications and your symptoms getting worse. The right treatment for you will depend on which symptoms you have and how bad they are. If you have mild Crohn’s disease, you may just need to take medicines when your symptoms come on. You may not even need any medicines. If your Crohn’s disease is worse, you may need to take other medicines every day to stop you having another flare-up. You may need to go into hospital for treatment if you have very bad symptoms.

A specialist inflammatory bowel disease (IBD) team will also support you. Your team will include a specialist nurse and doctor, and possibly a surgeon, pharmacist, dietitian and psychologist to cover all aspects of your care.

Medicines for Crohn’s disease

You may need medication to prevent a flare-up or to ease your symptoms. This may be just one medicine or several medicines. It’s important to keep taking your medicines to keep your symptoms under control.

The first medicine your doctor may prescribe is a corticosteroid (such as prednisolone and budesonide). These ease inflammation, but you usually only take them for a short time during a flare-up. This is because corticosteroids can cause side-effects such as acne, depression, high blood pressure, and diabetes.

If you have two or more flare-ups in 12 months, your doctor may prescribe you an immunosuppressant (such as azathioprine, mercaptopurine and methotrexate). These dampen down your immune system to reduce inflammation, but they may make you more likely to catch infections.

If the area around your bottom is affected by Crohn’s disease, your doctor may offer you antibiotics such as metronidazole or ciprofloxacin. These may help to reduce your chances of getting an infection or treat an infection.

If other treatments don’t help, your doctor may prescribe you biological therapies, such as:

  • infliximab
  • adalimumab
  • vedolizumab
  • ustekinumab

Your doctor can give you more information about these medicines.

Other medicines

Your doctor may also suggest you take medicines to ease specific symptoms such as diarrhoea, constipation or cramping pains. You may also need to use medicines for other symptoms such as mouth ulcers.

If you need pain relief, you can take over-the-counter painkillers such as paracetamol. Don't take non-steroidal anti-inflammatory medicines (NSAIDs) such as ibuprofen or aspirin because these can make your symptoms worse.

Always read the patient information leaflet that comes with your medicine. If you have any questions, ask your pharmacist or doctor for advice.

Surgery for Crohn’s disease

Surgery can’t cure Crohn’s disease, but your doctor may suggest you have an operation if:

  • you’ve recently been diagnosed and Crohn’s disease is only in the end of your small bowel (before it turns into the start of your large bowel)
  • you’ve tried several different medicines and they haven't worked
  • you have severe inflammation – you may have an operation to remove a part of your bowel that’s very badly inflamed
  • your surgeon needs to widen areas where your bowel has narrowed
  • you have complications of Crohn's disease such as an abscess or fistula

Complications of Crohn's disease

Crohn’s disease may make you more likely to have other problems with your digestive system such as the following.

  • A fissure. This is a cut in the wall of your anus that can hurt and bleed when you go to the loo.
  • A stricture (narrowing) in your bowel. A stricture can block part or all of your bowel and can cause pain, vomiting and swelling in your tummy.
  • An abscess (collection of pus). If inflammation causes an ulcer in your bowel wall, this can form a hole and the contents of your bowel may leak through the hole and cause an abscess. The abscess may then spread through to your skin or into a nearby part of your body. This can cause a fistula (see below).
  • A fistula. This is an abnormal connection between a hole in your bowel and surrounding tissues. A fistula can form 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 absorbs vitamins and minerals from food. This is especially true for iron, folic acid and vitamin B12.
  • Delayed puberty in children.
  • Bowel cancer. Crohn's disease makes you more likely to get bowel cancer in the future so it’s important to have your bowel checked regularly.
  • Crohn’s disease can make you more likely to get osteoporosis, which is when your bones become fragile and weak. You may need to have some tests to check your bone density and risk of a bone fracture. Corticosteroid medicines can also increase your risk of osteoporosis. If you take corticosteroids regularly, you may need to take calcium and vitamin D supplements to keep your bones healthy.

Living with Crohn's disease

If your symptoms are mild or clear up for a while, Crohn's disease may have little effect on your day-to-day life. But when you have a flare-up, your symptoms can make life more difficult. You may need to take time off work or cancel social arrangements. If you tell your friends, family and work colleagues about your Crohn’s disease, they will be better able to support you.

If you have diarrhoea regularly, it can make your skin sore. So, it’s important to look after your skin properly. Ask your doctor, specialist nurse or pharmacist for advice.

If you find that certain foods make your Crohn’s disease worse, it can be hard to know what to eat. It may help if you eat small meals regularly, rather than a few large meals each day. Your doctor can refer you to a dietitian for advice if you need support.

If Crohn’s disease stops you eating properly, you may lose weight and feel very unwell. Your doctor or dietitian may recommend that you take dietary supplements to make sure you get all the essential nutrients your body needs.

Crohn’s disease can be hard to deal with, especially because it’s so unpredictable. Stress can make your symptoms worse so try to relax as much as you can. Relaxation therapies, meditation, yoga or even listening to music may help to reduce the risk of a flare-up.

Rest if you’re feeling tired or having a flare-up. But try to do some form of activity every day if you can because it’s good for your health. You don’t necessarily have to give up your favourite sport or exercise just because you have Crohn’s disease. But you may need to plan in advance, in case you need unexpected toilet breaks. And you should recognise when you need to rest.

If you have a long-term medical condition such as Crohn’s disease, it can make you feel down. It can also affect your relationships and may lead to depression or anxiety. It’s important to discuss your feelings with your doctor or specialist nurse. You may find it helpful to see a counsellor or join a support group to meet other people who have Crohn’s disease.

Frequently asked questions

  • Several things can trigger Crohn’s disease in susceptible people. These include smoking and regularly taking non-steroidal anti-inflammatory drugs such as ibuprofen. Some people develop Crohn’s disease after they’ve had a bout of gastroenteritis. Stress can trigger a flare-up but for most flares, the cause is unknown.

    See our section on causes of Crohn’s disease for more information.

  • It can vary. Some people have mild Crohn’s disease and only have occasional symptoms, while others have severe symptoms that really affect their life. If you have Crohn’s disease, you’ll probably have periods of time when your symptoms flare up and other times where they go away.

    See our section About Crohn’s disease for more information.

  • You may get a number of symptoms during a Crohn’s attack (flare-up). These include diarrhoea, tummy pain and feeling (or being) sick. You can also feel extremely tired and generally unwell. You may start to lose weight because your body doesn’t absorb nutrients as it should.

    See our section on symptoms of Crohn’s disease for more information.

  • Doctors don’t yet know the exact reasons why some people develop Crohn’s disease. But you’re more likely to get Crohn’s disease if it runs in your family. If you’ve inherited the genes for Crohn’s disease, you may be more likely to get the condition if it’s triggered by something like smoking.

    See our section on causes of Crohn’s disease for more information.



Did our information help you?

We’d love to hear what you think. Our short survey takes just a few minutes to complete and helps us to keep improving our health information.


About our health information

At Bupa we produce a wealth of free health information for you and your family. This is because we believe that trustworthy information is essential in helping you make better decisions about your health and wellbeing.

Our information has been awarded the PIF TICK for trustworthy health information. It also follows the principles of the The Information Standard.

The Patient Information Forum tick

Learn more about our editorial team and principles >

Related information


  • Discover other helpful health information websites.
    • Crohn's disease. NICE Clinical Knowledge Summaries. cks.nice.org.uk, last revised August 2020
    • Crohn's disease. Patient. patient.info, last edited 30 August 2019
    • Crohn's disease. BMJ Best Practice. bestpractice.bmj.com, last reviewed 27 June 2021
    • Nutrition in gastrointestinal diseases. Oxford Handbook of Nutrition and Dietetics. Oxford Medicine Online. oxfordmedicine.com, published online April 2020
    • Crohn’s disease: management. National Institute for Health and Care Excellence (NICE). nice.org.uk, published May 2019
    • Crohn disease. Medscape. emedicine.medscape.com, updated 26 July 2019
    • Rolhion N, Darfeuille-Michaud A. Adherent-invasive Escherichia coli in inflammatory bowel disease. Inflamm Bowel Dis 2018; 13(10):1277–83. doi:10.1002/ibd.20176
    • Food. Crohn's and Colitis UK. www.crohnsandcolitis.org.uk, last amended May 2021
    • Crohn's disease. Crohn's and Colitis UK. www.crohnsandcolitis.org.uk, last reviewed October 2016
    • Narula N, Wong ECL, Dehghan M, et al. Association of ultra-processed food intake with risk of inflammatory bowel disease: prospective cohort study. BMJ 2021; 374:n1554. doi: 10.1136/bmj.n1554
    • Tests and investigations for IBD. Crohn's and Colitis UK. www.crohnsandcolitis.org.uk, last reviewed May 2017
    • Capsule endoscopy. Medscape. emedicine.medscape.com, updated 21 January 2020
    • Crohn's disease. NICE British National Formulary. bnf.nice.org.uk, last updated 9 July 2021
    • Personal communication, Dr Ian Arnott, Consultant Gastroenterologist, 30 July 2021
    • Steroids. Crohn's and Colitis UK. www.crohnsandcolitis.org.uk, last reviewed October 2019
    • Prednisolone. NICE British National Formulary. bnf.nice.org.uk, last updated 9 July 2021
    • Azathioprine. NICE British National Formulary. bnf.nice.org.uk, last updated 9 July 2021
    • Surgery for Crohn’s disease. Crohn's and Colitis UK. www.crohnsandcolitis.org.uk, last reviewed June 2017
    • Anal fissure. Medscape. emedicine.medscape.com, updated 24 July 2020
    • Osteoporosis – prevention of fragility fractures. NICE Clinical Knowledge Summaries. cks.nice.org.uk, last revised May 2020
    • Diarrhoea and constipation. Crohn's and Colitis UK. www.crohnsandcolitis.org.uk, last reviewed September 2018
    • Mental health and wellbeing. Crohn's and Colitis UK. www.crohnsandcolitis.org.uk, accessed 28 July 2021
    • What to do if you have Crohn’s or colitis and think you are having a flare-up. Crohn's and Colitis UK. www.crohnsandcolitis.org.uk, published 26 March 2020
    • Living with Crohn's or colitis. Crohn's and Colitis UK. www.crohnsandcolitis.org.uk, last amended March 2019
  • Reviewed by Rachael Mayfield-Blake, Freelance Health Editor, September 2021
    Expert reviewer, Dr Ian Arnott, Consultant Gastroenterologist and Dr Ade Adeniyi, General Practitioner
    Next review due September 2024

ajax-loader