crohnsCrohn's disease is an ailment that causes inflammation of the lining of any part of the digestive system, which can start at your mouth and end in your back passage. Most commonly it occurs in the small intestine (ileum) or the large intestine (colon) and involves an immune reaction. In Crohn's disease, the ileum becomes inflamed, which makes it difficult to digest food which can lead to a lack of nutrients in the body, further suppressing the immune system. At its worst sufferers of Crohn's disease can develop malnutrition.

If Crohn's disease simply affects the small intestine, diarrhoea and undernourishment are the result. When the large intestine is also inflamed, diarrhoea can be severe. Diarrhoea combined with malnutrition may lead to anaemia and low levels of essential vitamins which can cause serious problems for many people, especially children.


Symptoms of Crohn's disease vary between sufferers and depend on which part of the digestive system is inflamed. Some people will only ever have mild symptoms, others will have severe symptoms. The most common are:

  • Recurring diarrhoea
  • Stomach pain especially after eating
  • Fatigue (extreme tiredness)
  • Unintended weight loss
  • Blood and mucus in your faeces (stools)

Less common symptoms include

  • Fever of 38°C (100°F) or above
  • Feeling or being sick
  • Joint pain and swelling (arthritis) or areas of painful, red and swollen skin – usually on the legs
  • Inflammation and irritation of the eyes (uveitis)
  • Mouth ulcers

Symptoms tend to come and go and sometimes sufferers can enjoy long periods of no or few symptoms: this is known as remission. Unfortunately it will be followed by times when symptoms flare up again.


The exact cause of Crohn's disease is currently unknown although researchers suggest it could be due to a number of factors. Genetics for example is one factor. Approximately 3 in 20 people with Crohn's Disease have a close relative who is also a sufferer and certain ethnic groups are more at risk than others.

Another factor to consider in Crohn's Disease is a problem with the immune system. Normally the immune system protects us against harmful bacteria while "friendly bacteria" help us to digest food. In Crohn's disease, the immune system tries to kill all bacteria, regardless of whether they are friendly or not. This causes most of the inflammation associated with the disease. Previous infection may also be an issue, with some researchers suggesting that sufferers of Crohn's Disease are seven times more likely to have traces of a bacterium called Mycobacterium avium subspecies paratuberculosis (MAP) in their system. MAP is commonly found in cows, sheep and goats and is known to survive the pasteurisation process (where milk is treated with heat to kill bacteria), so it is possible that people have become infected with MAP by drinking milk from contaminated animals.

Other factors include smoking, and environmental factors. Crohn's disease is a "disease of the rich" meaning it is more prevalent in the developed world. It has become more widespread as people have become wealthier since the 1950s. This may be because in the West, children grow up in germ-free environments, so their immune system does not fully develop due to a lack of exposure to childhood infections.


There is currently no cure for Crohn's disease; however treatment can improve or reduce the symptoms. The first port of call for treatment is steroid medication (corticosteroids) which reduces inflammation including prednisolone tablets or hydrocortisone injections. The dose is reduced as symptoms improve because of side effects such as weight gain, and thinning of the bones. Milder steroids are available but are less effective. Medicines to suppress your immune system (immunosuppressants) may also be used but again there are side effects including vomiting, fatigue and liver problems.

If you have severe Crohn's disease biological therapies can be used to reduce symptoms. These are powerful immunosuppressants, medication which has been developed using naturally occurring biological substances, such as antibodies and enzymes. These medicines can cause allergic reactions such as temperature, itchy skin, aches and pains, and problems swallowing.

Surgery is sometimes recommended to reduce symptoms. Resection involves removing the inflamed area of the intestine and stitching the healthy sections together, while alternatively, a temporary surgical procedure known as ileostomy will divert digestive waste away from the large intestine to give it a chance to heal. During this operation, the end of the small intestine (the ileum) is disconnected from the colon and re-routed through a hole made in the abdomen, which is known as a stoma. An external bag is attached to the opening to collect waste products and after a few months a second operation reverses the procedure.

Possible Complications

Complications of Crohn's disease include fistulas (channels that develop between two sections of the digestive system), or intestinal narrowing (stricture) both of which need to be treated with surgery. A stricture is caused by scarring of the intestines which can then begin to block and you will not be able pass stools. Left untreated, the bowel can rupture. A fistula is where scarring causes excessive inflammation and ulcers develop. Large fistulas can become infected and cause symptoms such as pain, fever, blood in the stools and leakage of stools into your underwear.
Other complications can include: osteoporosis; iron deficiency anaemia; vitamin B12 or folate deficiency anaemia and rare skin reactions. Some people with Crohn's disease have a slightly increased risk of developing colorectal cancer in later life.

Diagnosing Crohn's Disease

Initial diagnosis of Crohn's disease can be problematic as it has similar symptoms to several other conditions. Your GP will want to know about your diet, any traveller's diarrhoea you may have had, what medication you are taking and your family medical history. Your GP will run standard tests such as pulse and blood pressure checks, height and weight, take your temperature, and examine your tummy. You will probably have blood tests which can check for anaemia, inflammation and infection. You may be asked to provide a stool sample to check for blood and mucus or other infections.

A colonoscopy test will be used to examine the inside of your colon. This involves inserting a long flexible tube with a camera on the end, known as an endoscope, into your colon through your back passage (rectum). A biopsy can be taken at the same time. Alternatively a wireless capsule endoscopy may be used which involves swallowing a small capsule. This transmits images to a recording device worn on a belt or in a small shoulder bag. A few days after the test, the capsule passes out in your stools.

Other tests that may be run include magnetic resonance enterography/enteroclysis (MRE) and tomography enterography/enteroclysis (CTE) scans which use a contrast liquid to show your small intestine during the scans. A small bowel enema (SBE) and small bowel follow through (SBFT) are two similar tests that have traditionally been used to examine the whole of the inside of the small intestine. During an SBE/SBFT, a local anaesthetic spray is used to numb the inside of your nose and throat. A tube is passed down your nose and into your throat, before being threaded into your small intestines and barium is passed down the tube. The barium coats the lining of your small intestines so that they show up clearly on X-rays.

Foods to avoid

Certain foods trigger intestinal symptoms, so Crohn's Disease sufferers need to manage their diets which will in turn ease symptoms of wind, bloating, abdominal pain, cramping and diarrhoea. The foods that trigger symptoms differ for each person with Crohn's disease but can include alcohol, milk and dairy products, spicy food, fatty food, raw vegetables and high-fibre foods. A low- fibre with low-residue diet can help to ease symptoms so avoid corn hulls, nuts, raw fruit, seeds and vegetables.

It is recommended that Crohn's disease sufferers follow a high-calorie, high-protein diet, eat regular meals, plus an additional two or three snacks, and take doctor-recommended vitamin and mineral supplements.

Keeping a daily food diary can help you to self-manage Crohn's disease. Simply note what you eat and when and then record any symptoms you have in the aftermath. Experiment with leaving items out of your diet or increasing others that do not exacerbate the problem.

Image credit: wavebreakmediamicro / 123RF Stock Photo

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