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Crohn's disease

Crohn’s disease is a form of inflammatory bowel disease. We take a look at symptoms, causes and treatment options

Terrible stomachache
Crohn’s disease is one of the two most common types of inflammatory bowel disease (IBD). It is thought to affect one in every 650 people in the UK, making it more common than many people realise.1

The other most common type of IBD is ulcerative colitis. Ulcerative colitis is more common than Crohn’s disease, affecting an estimated one in every 420 people in the UK.1

Inflammatory bowel diseases are lifelong conditions that are estimated to affect around 500,000 people in the UK, although many people go undiagnosed, meaning that the true number could be higher.2

Crohn’s disease can cause painful and debilitating symptoms that slowly erode the quality of life of those people that live with it. While there’s not currently a cure for Crohn’s disease, early diagnosis and prompt treatment can make it much easier to live with the condition.

We help many people with Crohn’s disease at our Circle Health Group hospitals, offering fast diagnosis and effective treatment. Our expert team of consultant gastroenterologists are on hand to help them manage their Crohn’s and enjoy life to the fullest. 

“With early diagnosis and intervention, patients with Crohn’s disease are able to live normal, active lives.”

Dr Iqbal Khan, consultant gastroenterologist at Three Shires Hospital

Crohn’s disease is a type of inflammatory bowel condition. It causes inflammation throughout the digestive system, rather than just in the bowel.

While Crohn’s disease affects people of all ages, the symptoms most often start in childhood or adolescence. However, it can also manifest later in life, particularly among female smokers.3

There isn’t currently a cure, but there are treatments that can help those with the condition manage their symptoms and prevent it from affecting their quality of life.

Unfortunately, there is no definitive answer as to why some people develop Crohn’s disease and others don’t.

Genetic causes of Crohn’s disease

However, genetics do appear to play a role. A study by the National Human Genome Research Institute found that having a close relative with Crohn’s disease increases the chances of an individual developing the condition.

  • 20% of people with Crohn’s disease have a close relative with a form of inflammatory bowel disease
  • If one parent has Crohn’s disease, a child has a 7–9% risk of developing it too, but if both parents have it, this risk increases to as much as 35%4

Other causes of Crohn’s disease

Research has also indicated that there are a number of other factors that could influence the development of Crohn’s disease, including poor diet and nutrition, smoking, taking non-steroidal anti-inflammatory medications, and prolonged periods of stress.

It’s also possible that viruses or bacteria could trigger the disease too. This is because when the body is affected by a harmful microorganism, the immune system attacks it to fight it off, and it’s possible that the immune system attacks the cells in the digestive system too.

However, there isn’t currently significant evidence to state that any of these reasons alone are a definitive cause of Crohn’s disease. 

“Many people think that poor diet is the only cause of inflammatory bowel diseases and flare-ups, but there is no special diet for patients with Crohn’s,” explains Dr Khan. “If you find specific foods are making your symptoms worse, avoid them, but otherwise following a healthy, balanced diet is the best thing to do – unless otherwise advised by your consultant.”

There are a variety of symptoms associated with Crohn’s disease. These can vary in severity, and they can come and go, with many patients experiencing periods of remissions between flare-ups of the condition.

When Crohn's disease symptoms develop, it usually happens gradually, but some people will experience a sudden onset that takes them by surprise. 

Common symptoms of Crohn’s disease include:

  • Diarrhoea
  • Fatigue
  • Abdominal pain and cramping
  • Fever
  • Blood in bowel movements
  • Mouth sores
  • Reduced appetite
  • Unexplained weight loss
  • Pain or drainage near or around the anus as a result of inflammation from a fistula (a tunnel that develops in the skin)

In severe cases of Crohn’s disease, additional symptoms may also develop, including:

  • Anaemia (iron deficiency)
  • Kidney stones
  • Inflammation of the skin, eyes and joints
  • Inflammation of the liver or bile ducts
  • Delayed growth/sexual development in children

Crohn’s disease symptoms can range from mild to severe. They will also vary from one person to another — Crohn’s disease is very individual.

Many people are surprised to learn that there are different types of Crohn’s disease. Some are more common than others. The correct diagnosis will help ensure that you get the best treatment for you as quickly as possible.

The type of Crohn’s disease that you have can also affect which symptoms you are more likely to experience. It’s important to note that many people experience inflammation in multiple parts of the digestive system, meaning that they can be diagnosed with more than one type of Crohn’s.

Terminal ileal and ileocaecal Crohn’s disease

These are two of the most common forms of Crohn’s disease. Terminal ileal Crohn’s affects the end of the small intestine, known as the ileum. However, if it also affects the beginning of the large bowel, it is called ileocaecal Crohn’s.

Bloody bowel movements aren’t common, but they may appear very dark or black in colour. Patients also usually suffer from abdominal pain in the lower right side of the belly, diarrhoea and weight loss. Blood tests may flag up anaemia as a possible cause of your symptoms.

Small bowel Crohn’s disease

Also known as ileitis or jejunoileitis depending on which part of the small bowel is affected, this type of Crohn’s disease typically affects children and young people.

Again, blood tests may suggest low iron levels, and patients will normally experience gradual but unexplained weight loss, along with loose bowel movements and abdominal pain.

Colonic Crohn’s disease

When Crohn’s disease occurs in the large intestine or large bowel, it can be referred to as Crohn’s Colitis, but this isn’t the same as ulcerative colitis.

Instead, inflammation means that the colon is unable to hold as much waste as normal and so patients tend to experience very frequent bowel movements and a sudden urgency to pass them. Blood and mucus may be present in the stools, too.

Gastroduodenal Crohn’s disease

Sometimes Crohn’s disease occurs in the upper part of the digestive system, including the duodenum, stomach or even oesophagus.

This type of Crohn’s disease is quite rare, and it can be accompanied by Crohn’s in other parts of the digestive system too. Patients with this type of Crohn’s can experience indigestion, nausea with or without vomiting, loss of appetite and pain.

Perianal Crohn’s disease

Many patients with Crohn’s disease will experience inflammation around the anus, either on its own or alongside the disease affecting other areas. This common type of Crohn’s disease can cause a range of unique symptoms that often become noticeable before those associated with intestinal signs of the condition.

Signs of perianal Crohn’s disease include:

  • Tears or splits in the anal canal, called fissures, that can result in pain and bleeding while passing stools
  • Skin tags and haemorrhoids around the anus
  • Anal abscesses that can become painful and cause fevers
  • Narrow tunnels or passageways developing between the gut and skin, called fistulas

Unsurprisingly, perianal Crohn’s can have a devastating effect on a patient’s quality of life. Without prompt treatment, there is a real risk of bowel incontinence and even a loss of the back passage which could result in the need for a permanent stoma bag.  

Oral Crohn’s disease

A very rare form of Crohn’s disease, oral Crohn’s affects the mouth and is sometimes called orofacial granulomatosis. It is most often seen in children and adolescents and results in swollen lips, mouth fissures and sometimes ulcers.

Oral Crohn’s disease is thought to be caused by nutritional deficiencies such as iron, folate and B12.

If you notice any persistent changes in your bowel habits, or any of the following symptoms, we recommend that you make an appointment with your GP as soon as possible:

  • Abdominal pain
  • Blood in your bowel movements
  • Nausea
  • Vomiting
  • Ongoing diarrhoea that doesn’t respond to over-the-counter diarrhoea relief medications
  • Unexplained fever lasting more than a couple of days
  • Unexplained weight loss

Your GP will almost certainly arrange for you to undergo some diagnostic testing to assess the likelihood that you are suffering from Crohn’s, before referring you to a consultant gastroenterologist for confirmation and treatment.

In the very earliest stages of the diagnostic process, your GP will probably refer you for blood testing.

This is because a full blood count will reveal if your inflammatory markers are high — something which is indicative of Crohn’s disease, as well as other health conditions. A rising platelet count is another marker for inflammatory disease, and this will likely be checked for also.

Finally, your GP may ask for a stool sample for analysis. At this point, if the results of your diagnostic testing point towards an inflammatory bowel disease, you’ll be referred to a consultant gastroenterologist.

There is no single test that can be used to diagnose Crohn’s disease. Instead, your consultant gastroenterologist will perform a variety of different evaluations to confirm both that you are suffering from Crohn’s, and which variety you are affected by.

Here are just a few of the tests that you may need to undergo:

Blood tests

Although your GP may have already requested blood tests, your consultant may also ask you to have further samples taken as part of the diagnostic process. This is because blood tests reveal important information about how well your body is functioning.

Some of the blood tests that may be requested could include a full blood count, liver function tests, measuring electrolytes, urea and creatinine in the blood, and more.

Stool sample

Stool samples might not be pleasant to collect, but they can be invaluable for determining whether a flare-up of an inflammatory bowel disease like Crohn’s has been caused by an infection.

You’ll only need a small sample, about the size of a walnut, collected in a clean, screw-top container.


An endoscopy is a minimally invasive test that enables your consultant to look directly at the digestive system, without needing to open you up.

An endoscope is a long, thin tube with a camera and light on one end. It can be inserted into the body via a very small incision — usually either via the mouth to look at the top end of the digestive system, or rectally to look at the lower end of the digestive system. As it passes through, the light illuminates inside your body while the camera feeds back live images, which appear on a screen in the room.

In some cases, an endoscopy is also used to take a sample of part of the digestive system. This is called a biopsy and involves scraping cells from the lining of the gut so that they can later be examined under a microscope.

If necessary, the endoscope can also be used to remove any polyps (small growths) which may be present, and to dilate (using balloons) narrowing caused by inflammation called strictures.

An endoscopy is usually performed using local anaesthetic, though sedation may be possible for particularly anxious or nervous patients. Your consultant will explain in more detail how you will need to prepare and what to expect from this common and effective diagnostic test.

Capsule endoscopy

More recently, some healthcare providers are now offering cutting-edge capsule diagnostics, which work in a similar way to an endoscopy but without the tube.

Instead, a pill containing a micro-camera is swallowed, and this captures images throughout the digestive process.

Consultation and physical examination

Of course, your consultant will also speak to you in-depth about the symptoms that you have been experiencing and how they are affecting your day-to-day life.

It may also be necessary for you to have a physical examination, particularly if your consultant has reason to believe that you are affected by perianal Crohn’s.

The good news is that there are many potential treatments for Crohn’s disease. Which treatment(s) your consultant will recommend for you will primarily depend on the part of your digestive system that has been affected, and the severity of your condition.

As with most diseases, the earlier treatment begins, the better the outcome for the patient usually is.

Crohn’s disease medication

Medications are always the first line of treatment for Crohn’s. There are several different types of Crohn’s disease medication available — these may be used alone or in combination to provide the greatest relief from the disease.

Firstly, patients may be given steroid medications. These counteract inflammation and start working within just a few days of being taken. They are usually administered orally, although in some cases injectable steroids may be recommended instead.

Immunosuppressants are another highly successful treatment for Crohn’s disease. As their name suggests, these work by reducing the activity of your immune system so that it doesn’t attack the healthy cells of your digestive system.

Again, these can be taken orally or injected, and must be administered exactly as directed. Common side effects include nausea, vomiting and increased risk of infections and liver problems and you may be asked to have regular blood tests to monitor these side effects.

Biological medicines are the strongest type of drug prescribed for Crohn’s disease, and usually only recommended after other medications have failed. That’s because they are administered via injection or IV drop and can cause a wide range of potentially more serious side effects.

Crohn’s disease surgery

Surgery for Crohn’s disease is normally only recommended for one of two reasons.

The first is because medications are proving unsuccessful in keeping your Crohn’s under control and you are still suffering from debilitating symptoms. This is usually the most common reason for a patient with Crohn’s to undergo surgery.

The second is because the patient has started to develop strictures. These are areas of narrowing in the intestines caused by repeated cycles of continued inflammation and healing triggering the production of scar tissue.

Over time, this scar tissue can accumulate and cause narrow areas where obstructions (which can be life-threatening) can occur. Surgery involves placing a balloon into the area via an endoscope, which is then inflated to dilate the available space. However, in some cases, it is necessary to remove small sections of the intestine or bowel instead.

It is important to note that it’s not possible to remove large sections of the small bowel since this can interfere with nutrition absorption.

Temporary ileostomy

Sometimes, patients may also need a temporary ileostomy. This is where the small bowel is diverted through an opening in the abdomen, called a stoma, and waste material is collected in a bag.

This may be recommended to give the large intestine (colon) time to heal and recover following surgery. 

“Our aim is to avoid surgery if we can,” explains Dr Khan. “With early diagnosis, we can help people to avoid severe treatments and learn to manage their Crohn’s with minimal medical intervention.”

Crohn’s disease isn’t usually life-threatening except in very severe, undiagnosed cases.

Although extremely rare, there have been cases where Crohn’s disease has been fatal. This has happened in cases of undiagnosed or untreated Crohn’s, where the chronic inflammation that occurs causes severe complications such as acute infection, intestinal obstruction or colorectal cancer.

However, for the vast majority of patients, the risk of developing these complications is very small. As with all diseases, early diagnosis and treatment is crucial to living well with Crohn’s disease.

Studies have found that you may be more likely to get bowel cancer if you have Crohn’s disease.5

The risk is initially very low, but the longer you have the condition, the higher your risk becomes. For example, after 10 years with Crohn’s, you have around a 1 in 100 chance of developing bowel cancer. However, this increases to a 1 in 5 chance after 30 years.

If you have had Crohn’s disease for some time, you may be recommended to have regular bowel cancer screenings. Your Circle Health Group team will discuss this with you in more detail.

A diagnosis of Crohn’s disease can be worrying, but with the right medical support and care from Circle Health Group Hospital teams, patients can quickly learn to manage their symptoms and enjoy a full and active life.

If you would like more information specifically about Inflammatory Bowel Disorders including Crohn’s, Dr. Khan recommends that you visit the website for the National Association for Crohn’s and Colitis where you can discover a variety of resources.

Alternatively, please make an appointment with the friendly and discreet gastroenterology team at one of our Circle Health Group hospitals today. You can book an appointment online or call us on 0141 300 5009.

Content reviewed by Dr Iqbal Khan in May 2022. Next review due May 2025.

References and further reading

  1. Crohn’s disease, Crohn’s & Colitis UK
  2.  Inflammatory bowel disease, UK Parliament Committees
  3.  High rates of smoking especially in female Crohn’s disease patients and low use of supportive measures to achieve smoking cessation – data from the Swiss IBD cohort study, Journal of Crohn’s and Colitis
  4.  About Crohn’s disease, National Human Genome Research Institute
  5. Bowel cancer and IBD, Crohn’s & Colitis UK

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