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Crohn’s disease

What is Crohn’s disease?

Crohn’s disease is a condition that causes inflammation of the digestive system (also known as the gastrointestinal tract or gut).  Inflammation is the body’s reaction to injury or irritation, and can cause redness, swelling and pain.

Crohn’s Disease is one of the two main forms of Inflammatory Bowel Disease (IBD).  The other main form of IBD is a condition known as Ulcerative Colitis (UC). Crohn’s is sometimes described as a chronic condition.  This means that it is ongoing and life-long, although you may have periods of good health (remission) as well as times when symptoms are more active (relapses or flare-ups). In many people the disease runs a benign course with few flare-ups, while other people may have more severe disease. Crohn’s Disease is not infectious.

At present there is no cure for Crohn’s, but drugs, and sometimes surgery, can give long periods of relief from symptoms.

How does Crohn’s affect the gut?

As you can see from the diagram, the gut (digestive system) is like a long tube that starts at the mouth and ends at the anus.  When we eat, the food goes down the oesophagus into the stomach, where gastric (digestive) juices break it down to a porridge-like consistency.

The partly digested food then moves through the small intestine (also known as the small bowel). Here it is broken down even further so that the nutrients (useful parts of the food) can be absorbed into the bloodstream.  The waste products from this process – liquid and non-digestible parts of food – then pass into the colon (also known as the large intestine or large bowel).  The colon absorbs the liquid, and the leftover waste forms solid faeces (stools).  These collect in the last part of the colon and the rectum until they are passed out of the body in a bowel movement.  Crohn’s causes ulceration and inflammation, which affects the body’s ability to digest food, absorb nutrients and eliminate waste, in a healthy way.

Crohn’s can affect any part of the gut but is most likely to develop in the ileum (the last part of the small intestine) or the colon.  The areas of inflammation are often patchy, with sections of normal gut in between.  A patch of inflammation may be small, only a few centimetres across, or extend quite a distance along part of the gut.  As well as affecting the lining of the bowel, Crohn’s may also penetrate deeper into the bowel wall causing abscesses and fistulas (abnormal tracts or passages between organs such as between two sections of bowel, or the bowel and skin).

What are the main symptoms?

Crohn’s symptoms may range from mild to severe and will vary from person to person.  They may also change over time, with periods of good health when you have few or no symptoms (remission), alternating with times when your symptoms are more active (relapses or ‘flare-ups’).  Crohn’s is a very individual condition and some people may remain well for a long time, even for many years, while others may have more frequent flare-ups.

Your symptoms may also vary depending on where in your gut you have Crohn’s. However, the most common symptoms during a flare-up are:

  • Abdominal pain and diarrhoea Sometimes mucus, pus or blood is mixed with the diarrhoea.

  • Tiredness and fatigue this can be due to the illness itself, from the weight loss associated with flare-ups or surgery, from anaemia (see below) or to a lack of sleep if you have to keep getting up in the night with pain or diarrhoea.

  • Feeling generally unwell some people may have a raised temperature and feel feverish.

  • Mouth ulcers

  • Loss of appetite and weight loss Weight loss can also be due to the body not absorbing nutrients from the food you eat because of the inflammation in the gut.

  • Anaemia (a reduced level of red blood cells) You are more likely to develop anaemia if you are losing blood, are not eating much, or your body is not fully absorbing the nutrients from the food you do eat. Anaemia can make you feel very tired.

How will Crohn’s affect my life?

There is no single answer to this question because everyone is different, and people’s experiences vary greatly.  Also, much depends on the severity of your condition and whether your disease is in a quiet or active phase.  With medication, many people with Crohn’s have mild and infrequent symptoms of diarrhoea and pain, and their illness may not affect their lives very much.  Most people follow a course of intermittent relapses (flareups) with periods of well-being (remission) in between, when they can lead a full and complete working and social life.  Less commonly, some people have more frequent or continuous symptoms despite medical and surgical treatment and have to adapt their lifestyle considerably.

How common is Crohn’s disease?

It is estimated that Crohn’s disease affects about one in every 650 people in the UK.

Crohn’s is more common in urban than rural areas, and in northern, developed countries such as Northern Europe and North America, although the numbers are beginning to increase in developing nations.  Crohn’s is also more common in white people of European descent, especially those descended from Ashkenazi Jews (those who lived in Eastern Europe and Russia).

Crohn’s can start at any age, but usually appears for the first time between the ages of 10 and 40, although there is a small peak in the number of people diagnosed over the age of 60.

Recent surveys suggest that new cases of Crohn’s are being diagnosed more often, particularly among teenagers and children.  The reason for this is not clear.  Crohn’s appears to be slightly more common in women than in men.

It is also more common in smokers.

What causes Crohn’s disease?

Although there has been much research, we still do not know exactly what causes Crohn’s disease.  However major advances have been made over the past few years, particularly in genetics.  Researchers now believe that Crohn’s disease is caused by a combination of factors: viruses, bacteria, diet, smoking, certain medications, and stress have all been suggested as environmental triggers, but there is no definite evidence that any one of these is the cause of Crohn’s.

What are the different types of Chohn’s disease?

Crohn’s is often categorised according to which part or parts of the gut are most affected.  Sometimes it can affect more than one part of the gut. The main types are as follows:

Terminal ileal and ileocaecal

Crohn’s in the ileum (the last part of the small intestine) may be called ileal or sometimes ‘terminal ileal’ Crohn’s – because it is affecting the terminus or end of the ileum.  If it also affects the beginning of the large bowel it is known as ileocaecal Crohn’s.   This is one of the most common forms of Crohn’s Disease.  Typical symptoms are pain in the lower right side of the abdomen, especially after eating, diarrhoea and weight loss.  Any bleeding is unlikely to be visible in stools, but stools may appear black and blood tests may show that you are anaemic.

Small bowel

This type of Crohn’s is also referred to as ileitis or jejunoileitis, depending on the part of the small bowel affected.  Abdominal pain and diarrhoea are also typical symptoms of Crohn’s in the small bowel, along with nutrient deficiencies.  Again, the diarrhoea is unlikely to be blood-stained, but you may still have anaemia, and weight loss.  The small bowel is commonly affected in children and young people.

Colonic Crohn’s Disease in the colon (large intestine or large bowel) is often called Crohn’s Colitis

This is also a common form of Crohn’s Disease, but is not the same as Ulcerative Colitis.  The main symptom tends to be diarrhoea, with blood and mucus. Because of the inflammation, the colon cannot hold as much waste as normal and you may have very frequent bowel movements, especially if your rectum is inflamed. You may also have urgency to pass stools and tenesmus (feeling the need to pass a stool although the rectum is empty).

Gastroduodenal Crohn’s in the upper gut

The oesophagus, stomach or duodenum is much less common, but may occur on its own or alongside Crohn’s in other parts of the digestive system. Key symptoms include indigestion like pain, nausea with or without vomiting, loss of appetite, and weight loss and anaemia.

Perianal Crohn’s in the area around the anus (back passage) can occur on its own or at the same time as inflammation in other parts of the body.  It is quite common, and some people notice perianal symptoms before they develop intestinal symptoms.  It causes a number of symptoms, such as:

  • Fissures - these are tears or splits in the lining of the anal canal (back passage), which can cause pain and bleeding, especially during bowel movements.

  • Skin tags - small fleshy growths around the anus.

  • Haemorrhoids (piles) - swollen blood vessels in or around the anus and rectum.

  • Abscesses - collections of pus that can become swollen and painful. They are often found in the area around the anus and can cause a fever or lead to a fistula

  • Fistulas - these are narrow tunnels or passageways between the gut and the skin or another organ. In perianal Crohn’s, fistulas often run from the anal canal to the skin around the anus. They appear as tiny openings in the skin that leak pus or sometimes faecal matter. They can irritate the skin and are often sore and painful but can usually be treated with medication and/or surgery.

Oral Chron's

Chron's can occasionally affect the mouth. True oral Crohn’s is often referred to as ‘orofacial granulomatosis’ and is more likely to affect children, although it is rare. It typically causes swollen lips and mouth fissures. Some people with Crohn’s may develop mouth ulcers during large-ups. This can sometimes be due to nutritional deficiencies such as vitamin B12, folate and iron.

Can Crohn’s have complications within the bowel?

Crohn’s can sometimes cause additional problems in the gut.  These complications include strictures, perforations and fistulas.

  • Strictures ongoing inflammation and then healing in the bowel may cause scar tissue to form, which can create a narrow section of the bowel. This is known as a stricture. A stricture can make it difficult for food to pass through and, if severe, may cause a blockage (obstruction).  Symptoms include severe cramping, abdominal pain, nausea, vomiting and constipation.  The abdomen may become bloated and distended and the gut may make loud noises.

  • Perforations, although rare, inflammation deep in the bowel wall or a severe blockage caused by a stricture may lead to a perforation or rupture of the bowel, making a hole. The contents of the bowel can leak through the hole. This complication is a medical emergency.  Symptoms include severe abdominal pain, fever, nausea and vomiting.  In some cases, the leak will form an abscess.

  • Fistulas - some people with Crohn’s may develop a fistula. A fistula is an abnormal channel or passageway connecting one internal organ to another, or to the outside surface of the body. Most fistulas (also called fistulae) start in the wall of the intestine and might connect parts of the bowel to each other, or the bowel to the vagina, bladder, or skin (particularly around the anus).  A fistula forms when the inflammation in Crohn’s spreads through the whole thickness of the bowel wall and then continues to tunnel through the layers of other tissues.  Fistulas may be treated medically or with surgery.

How does Crohn’s affect other parts of the body?

Crohn’s Disease can also cause problems outside the gut. Some people with Crohn’s develop conditions affecting the joints, eyes or skin. These can be known as extraintestinal manifestations (EIMs) and often occur during active disease, but they can develop before any signs of bowel disease or during times of remission.  Many of these are not very common.

  • Joints Inflammation of the joints, often known as arthritis, is a common complication of Crohn’s Disease. It is most common in those with Crohn’s Colitis (Crohn’s Disease in the colon). The inflammation usually affects the large joints of the arms and legs, including the elbows, wrists, knees and ankles. Symptoms usually improve with treatment of intestinal symptoms, and there is generally no lasting damage to the joints.  Sometimes, the joints in the spine and pelvis become inflamed – a condition called ankylosing spondylitis (or sacroiliitis, in its less severe form). This can flare up independently of Crohn’s.  It often causes pain over the sacroiliac joints, on either side of the lower part of the spine.  Stiffness and pain in the spine itself may eventually lead to loss of flexibility. 

  • Skin Crohn’s can also cause skin problems. The most common skin problem is erythema nodosum, which affects about one in seven people with Crohn’s, and is more common in women than men. It consists of raised tender red or violet swellings 1.5cm in diameter, usually on the legs.  This condition tends to occur during flare-ups and generally improves with treatment for Crohn’s.  More rarely, a condition called pyoderma gangrenosum affects people with Crohn’s Disease.  This starts as small tender blisters or pustules, which become painful, deep ulcers. These can occur anywhere on the skin, but most commonly appear on the shins or near stomas. This condition is sometimes, but not always, linked to an IBD flare-up. 

  • Eyes problems affect some people with Crohn’s. The most common condition is episcleritis, which affects the layer of tissue covering the sclera, the white outer coating of the eye, making it red, sore and inflamed. Episcleritis tends to flare up at the same time as IBD.  The two other eye conditions linked with Crohn’s are scleritis (inflammation of the sclera itself) and uveitis (inflammation of the iris). 

  • Liver Primary Sclerosing Cholangitis (PSC) is a rare disease that affects up to one in 50 people with Crohn’s. It causes inflammation of the bile ducts and can eventually damage the liver. Symptoms include fatigue, itching, jaundice, and weight loss.

Could my symptoms be IBS?

IBS stands for Irritable Bowel Syndrome.  This is a different condition from IBD, although some of the symptoms are similar.  Like IBD, IBS can cause abdominal pain, bloating and bouts of diarrhoea or constipation.  However, it does not cause the type of inflammation typical of Crohn’s or UC, and there is no blood loss with IBS.  However, some people with Crohn’s may develop IBS like symptoms.  They may, for example, get diarrhoea even when their IBD is inactive.  IBS is more common in people with IBD than in the general population.

Can Crohn’s lead to cancer?

You may have a slightly increased risk of bowel cancer if you have had Crohn’s Disease affecting all or most of the colon for more than 8 to 10 years.  Bowel cancer risk is increased further if you have Primary Sclerosing Cholangitis, which also increases the risk of developing cancer in the liver.

What treatments are there for Crohn’s?

Treatment for Crohn’s may be medical, surgical or a combination of both.  If your condition is mild, not having any treatment might also be an option.

Dietary therapy may be another option for some people, particularly children.  Your treatment will depend on the type of Crohn’s you have and the choices you make in discussion with your doctor.

What drugs are used to treat Crohn’s?

Drug treatment for Crohn’s usually aims to reduce symptoms, control flare-ups and achieve remission, and then to prevent a relapse (maintain remission) once the disease is under control.  This can mean that you need to take your medication on an on-going basis, sometimes for many years.  Or you may need only a short course of drugs.

The main aim of drug treatment for Crohn’s disease is to reduce inflammation. The main types of drugs are:

  • Aminosalicylates (5-ASAs) reduce inflammation in the lining of the intestine. Examples include mesalazine, olsalazine, sulphalazine and balsalazide.

  • Corticosteroids (steroids) work by blocking the substances that trigger allergic and inflammatory responses in your body. They include prednisolone, budesonide, hydrocortisone, and beclometasone dipropionate.

  • Immunosuppressants suppress the immune system and reduce levels of inflammation. The main immunosupressants used in IBD are azathioprine, mercaptopurine and methotrexate. They are often used in patients who relapse when they come off steroids.

  • Antibiotics such as metronidazole and ciprofloxacin are sometimes used in Crohn’s disease (for example to treat abscesses or fistulas and after some types of surgery).

  • Biological drugs are the newest group of drugs used to treat Crohn’s. Anti-TNF drugs, such as infliximab, adalimumab, and golimumab target a protein in the body called TNF, preventing inflammation. Another type of biological drug is vedolizumab, which works by stopping white blood cells entering the lining of the gut and causing inflammation.  Ustekinumab, the newest biological drug to be recommended for Crohn’s, works by targeting two specific, naturally occurring proteins which play a key role in inflammatory and immune responses.

What is dietary treatment?

Some people with Crohn’s may be prescribed exclusive enteral nutrition (a special liquid-only diet), usually for 2-8 weeks.  People on this diet do not eat ordinary food or drink because the liquid diet provides them with all the nutrients they need.  Not everyone likes the taste of these specialised feeds, but they do come in a range of flavours.

Some people have found that taking the liquid ice-cold or through a straw makes it easier to drink.  It is commonly used in children because it can improve growth by providing easily digested nutrients.  It may also make it less likely that steroids are needed, by helping to ‘rest’ the bowel and allow it to heal.  Adults are less likely to need exclusive enteral nutrition, but this can be an option for treating flares.

What about surgical treatment for Crohn’s?

Over the last decade, advances such as the development of biological drugs have produced increasingly effective medical therapies for Crohn’s disease.  There have also been changes in the way surgery for Crohn’s is now managed.  For example, extensive resections (wide-spread removal of sections of the intestine) are now less common.  However, surgery remains an important treatment option, often in combination with medical therapies.  Up to 8 out of 10 people with Crohn’s will still need surgery at some point in their lives.

Do I need to change my diet?

There is no clear evidence that any food or food additive directly causes or improves Crohn’s.  Generally, the most important thing is to try to eat a nutritious and balanced diet so that you maintain your weight and strength, and to drink sufficient fluids to stop you getting dehydrated.  If you have a stricture, you may need to avoid eating ‘hard to digest’ or ‘lumpy’ foods that might cause a blockage.

Are there alternative approaches?

Some people with Crohn’s disease have found complementary and alternative medicines (CAM) helpful for controlling symptoms such as abdominal pain and bloating.  However, there are few reliable scientific studies to show the effectiveness of such therapies and it is possible that those people might have gone into remission coincidentally, given the unpredictable course of conditions such as Crohn’s.

Or there may have been a ‘placebo’ effect - there is evidence that if people take a placebo (a harmless inactive substance) but believe that it will help, then their symptoms may improve regardless of the actual effectiveness of that treatment.  Small studies have shown that acupuncture and a herbal medicine containing wormwood may help with Crohn’s disease, but more work is needed in this area.

Does Crohn’s run in families?

Crohn’s does tend to run in families, and parents with IBD are slightly more likely to have a child with IBD.  However, studies show for most people the actual risk is still relatively low.  If one parent has Crohn’s, the risk of their child developing IBD is generally thought to be between 5% and 10% - that is, for every 100 people with Crohn’s having a child, 5 to 10 of the children may develop IBD.  However, we still cannot predict exactly how Crohn’s is passed on.  Even with genetic predisposition - that is, an increased risk because of a person’s genes - additional factors are needed to trigger IBD.

How does Crohn’s affect children and young people?

As many as a quarter of people with IBD are diagnosed when under the age of sixteen.  Over the last few decades a number of studies have shown Crohn’s is occurring more often in children and young people.  There is also evidence to suggest that when Crohn’s begins in childhood the inflammation can be more severe and affect more of the bowel.

Inflammation of the bowel can affect growth patterns and may lead to delayed puberty.  Poor nutrition and prolonged use of steroids can also contribute to the slower growth found in many children with Crohn’s.

Crohn’s disease is a condition that causes inflammation of the digestive system (also known as the gastrointestinal tract or gut). 

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