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Crohn’s disease


Expert reviewer, Dr Ian Arnott, Consultant Gastroenterologist
Next review due April 2022

Crohn’s disease is a lifelong inflammatory bowel disease. It can trigger inflammation in any part of your digestive system, causing tummy pain, persistent diarrhoea and ulcers. It can also make you feel more tired than usual and lose weight.

Image showing the digestive system

About Crohn's disease

Crohn’s disease can run in families, but not everyone with Crohn’s has a relative with the condition. It most commonly starts in people between 15 and 30, but it can also start when you’re in your 50s or 60s. Men and women are affected equally. Children can have Crohn’s disease too.

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), large bowel (colon) and rectum. The inflamed areas are usually separated by unaffected (healthy) areas of bowel, called ‘skip lesions’.

Sometimes, other parts of your body, not just your digestive system, can be affected by Crohn’s disease. You may have aching joints, painful ulcers in your mouth or on your skin or sore eyes.

Crohn’s disease can’t be cured, but with treatment your symptoms may get better. If after a while your symptoms come back, this is called a relapse. Some people have mild Crohn’s disease with occasional symptoms. But others may have very bad symptoms, affecting all aspects of their life. Some people find it hard to cope, leading to depression or anxiety.

Crohn’s disease is one of the two major types of inflammatory bowel disease (IBD) – the other is ulcerative colitis.

Symptoms of Crohn's disease

If you have Crohn's disease, your symptoms may range from mild to very bad. They may change over time and flare up and down. Some people don’t have specific or bad digestive symptoms, so they’re not diagnosed with Crohn’s disease for many years.

The main symptoms of Crohn's disease include:

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

Crohn’s disease can also affect other parts of your body too. 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 the above symptoms, see your GP.

Causes of Crohn's disease

Doctors don’t know 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. Up to one-in-five people with Crohn’s disease has a close relative with the condition. 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.

Your immune system may react abnormally to certain bacteria or viruses in your bowel, causing inflammation. Some people develop Crohn’s disease after they’ve had gastroenteritis (a stomach or bowel infection). Crohn’s disease has been linked to changes in the types and numbers of bacteria that live naturally in your digestive system.

You’re more likely to have Crohn’s disease if you smoke. Smoking also makes you more likely to have regular flare-ups and need surgery to treat your Crohn’s disease. For more information, see our FAQ on Is smoking linked to Crohn’s disease?

You may be more likely to get Crohn’s disease if you take non-steroidal anti-inflammatory drugs, such as ibuprofen, regularly.

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.

Your GP may ask for a sample of your poo to see if you have a bacterial infection. They may also check for a substance called faecal calprotectin. If you have high levels of faecal calprotectin 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 stools, 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. Your doctor will insert a narrow, flexible, tube-like telescopic camera, called an endoscope, through your back passage (rectum) into your bowel. They can then look inside your bowel and take tissue samples that can be tested in a laboratory.
  • A CT scan or MRI scan. These scans create images of the inside of your tummy. You may have a CTE (computer tomography enteroclysis or enterography) or MRE (magnetic resonance enteroclysis or enterography) scan. These scans use a contrast medium – a solution that makes your small bowel show up more clearly. If you have a CT or MR enteroclysis, the contrast medium passes down a small tube through your nose into your small bowel. If you have a CT or MR enterography, your doctor gives you a solution of the contrast medium to drink.
  • A capsule endoscopy. If you have this test, your doctor will give you a small capsule to swallow. The capsule contains a small video camera. As it passes through your small bowel, the camera takes digital pictures that can be recorded and viewed on a screen by your doctor.

Treatment of Crohn's disease

You can use different treatments to help ease your symptoms and stop them coming back. But Crohn's disease can’t be cured and is a lifelong condition that flares up and down.

The right treatment for you will depend on which symptoms you have and how bad they are. If your Crohn’s disease is mild, you may just need to take medicines when your symptoms occur. You may not even need any medicines at all. If your Crohn’s disease is worse than this, 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.

Watching what you eat and drink may also help to ease your symptoms and prevent flare-ups.

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. Doctors and dietitians don’t recommend any specific diet, as everyone is different, and there aren’t any particular foods you should avoid. But you may find that certain foods, such as those high in fibre, can make your symptoms worse.

You may find it helpful to keep a food diary to see if anything in particular triggers your symptoms. Some people have pain if they eat stringy beans, the pith (spongy white bit) of citrus fruits, meat gristle and nuts. You may notice dairy products or spicy foods make your symptoms worse. But some people don’t have any particular triggers at all.

Some people with Crohn’s disease don’t absorb fat properly and need to eat a low-fat diet.

If you think certain foods make your Crohn’s disease worse, speak to a dietitian before you stop eating them. Otherwise, you could be missing out on essential nutrients.

You may be recommended to have a special liquid diet (elemental or polymeric diet) during a flare-up to ease your symptoms. Your doctor may also suggest a liquid diet if you have a flare-up but can’t or don’t want to take any medicines. These liquid diets are easier to digest than normal food and will give you all of the essential nutrients you need. They help to rest your bowel, boost your absorption of essential nutrients and ease any inflammation in your digestive system.

If your symptoms are so bad that you can’t eat enough normal foods to keep you well, your dietitian may recommend special drinks to give you more nutrients. But you shouldn’t use these foods to replace your usual diet.

Medicines for Crohn’s disease

You may be recommended to take medicines to prevent a flare-up or ease your symptoms. You may need to take just one medicine or several medicines. It’s important to keep taking any medicines you’ve been prescribed to keep your symptoms under control.

Corticosteroids (such as prednisolone and budesonide) may be the first medicines you’re prescribed. These ease inflammation, but you usually only take them for a short time during a flare-up. This is because they can cause side-effects such as diabetes, infections, cataracts, high blood pressure and osteoporosis. Budesonide has fewer side-effects than some of the other corticosteroids.

If you have two or more flare-ups in 12 months, you may be prescribed 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.

Your doctor may offer you antibiotics, such as metronidazole or ciprofloxacin, if the area around your anus (back passage) is affected. The antibiotics may help to reduce your chances of getting an infection and treat infections if they do occur.

If other treatments aren’t helping your Crohn’s disease, you may be prescribed biological therapies, such as infliximab, vedolizumab, adalimumab or ustekinumab.

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 non-digestive 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, as 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 tried several different medicines and they haven't worked.

You may have an operation to remove a part of your bowel that’s very badly inflamed. Or you may have surgery to widen areas where your bowel has narrowed because of a stricture. You may also need surgery if you have complications of Crohn's disease, such as an abscess or fistula. See Complications of Crohn’s disease for more information.

If you have surgery or narrowing of your bowel, you may have to go on a special diet or avoid certain foods. Your doctor will discuss this with you.

Although some people with Crohn’s need to have an operation (or several operations) to treat their symptoms and any complications, the number of people having surgery is thought to be decreasing.

Complications of Crohn's disease

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

  • A fissure. This is a tear in the wall of your anus that can hurt and bleed when you go to the loo.
  • A narrowing (stricture) in your bowel. A stricture can block part or all of your bowel. It 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 there. 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.
  • A fistula. This is an abnormal connection between a hole in your bowel and the tissues around it. A fistula can form between two parts of your bowel, or between your bowel and other parts of your body. This may be your bladder, vagina (in women) or skin.
  • Malnutrition and anaemia. Damage to your bowel can affect how well your body absorbs vitamins and minerals, especially iron, folic acid and vitamin B12, from food.
  • Bowel cancer. Crohn's disease makes you more likely to get bowel cancer. See our FAQ on Will I be more likely to develop bowel cancer? for more information.

Crohn’s disease can also affect other parts of your body, such as your joints, mouth, skin and eyes. If you’re worried about any symptoms, speak to your doctor.

Living with Crohn's disease

If your symptoms are mild or clear up for a while, you may find Crohn's disease has 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. Telling your friends, family and work colleagues about your Crohn’s disease will help them to give you any support you need.

A specialist inflammatory bowel disease (IBD) team will also be there to support your needs. Your team will include a specialist nurse and doctor, but may also include a surgeon, pharmacist, dietitian and psychologist. They can help to address all aspects of your care.

If you have diarrhoea regularly, this 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. Your doctor can refer you to a dietitian for advice if you’re struggling. It may help if you plan your meals in advance. It may also help if you eat small meals regularly, rather than a few large meals each day. See our FAQ on Will special foods help my Crohn’s disease?

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

It’s important to keep taking your medicines to keep your symptoms under control. If you’re in pain, speak to your doctor or nurse about the best forms of pain relief. If you don’t have any symptoms or don’t take medicines regularly, speak to your doctor about how often you should have medical check-ups. Look out for any signs that you’re having a flare-up, such as tummy pain, diarrhoea or unexplained weight loss. Make an appointment with your doctor if you’re worried at any time.

Crohn’s disease can make you more likely to get osteoporosis. This is when your bones become fragile and weak. You may be advised to have your bone density and risk of a bone fracture checked. You can reduce your chances of getting osteoporosis by doing weight-bearing exercise (such as walking) and eating calcium-rich foods (such as dairy products and broccoli). Corticosteroid medicines can also increase your risk of osteoporosis. If you take these regularly, you may be recommended to take calcium and vitamin D supplements to keep your bones healthy.

Crohn’s disease can be hard to deal with, especially because it’s so unpredictable. You may have to cope with sudden flare-ups or worry about new symptoms. 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 to stop you getting bored or frustrated. Keeping active is good for your posture, muscles, joints and bones too. You may not need 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 recognise when you need to rest.

Having a long-term medical condition, such as Crohn’s disease, can make you feel a bit 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 also have Crohn’s disease.

Frequently asked questions

  • If you have Crohn’s disease, this can make you more likely to get bowel cancer. This is most likely to happen if you’ve had Crohn’s disease for a long time. It depends on how bad the inflammation is in your bowel, and how much of your bowel is affected. It’s important to have your bowel checked regularly. If you’re diagnosed with bowel cancer early on, this means you can have treatment before the cancer has a chance to spread.

    Your first bowel screening will be 10 years after you’re first diagnosed with Crohn’s disease. You'll need to have a colonoscopy to check your large bowel for signs of cancer. This involves using a narrow, flexible, tube-like telescopic camera called a colonoscope. If your doctor sees any possible signs of cancer, they’ll take a small sample of tissue that’ll be tested in a laboratory.

    Your doctor will work out how likely you are to develop bowel cancer. They can explain your risk to you. They will check your bowel:

    • every five years if your risk of bowel cancer is low
    • every three years if your risk of bowel cancer is intermediate
    • every year if your risk of bowel cancer is high

    If you have any questions about Crohn's disease and bowel cancer, speak to your doctor.

  • If you smoke, you’re three to four times more likely to get Crohn’s disease than someone who doesn’t smoke. If you keep smoking after you’ve been diagnosed with Crohn’s disease, you’re more likely to have bad symptoms. If you keep smoking after you’ve had surgery for Crohn’s disease, your symptoms are more likely to come back.

    Stopping smoking may mean you’re less likely to have flare-ups in the future. Ask your pharmacist about how to quit smoking. You can be referred to local NHS Stop Smoking Services for support and advice. You’re more likely to quit successfully with help from a one-to-one counselling service, group session or healthcare professional.


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  • Reviewed by Laura Blanks, Specialist Health Editor, Bupa Health Content Team, April 2019
    Expert reviewer, Dr Ian Arnott, Consultant Gastroenterologist
    Next review due April 2022



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