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Crohn's Disease (CD)

About Crohn's Disease

In this section, you or a loved one can find out more about medical treatments, research studies and practical information about Crohn’s disease. Read on to find answers to some of your questions as well as links to other information. Being informed is an important first step towards becoming an active decision-maker in your care plan.

What is Crohn's Disease?

Crohn’s disease is an inflammatory bowel disease that causes inflammation and ulcers in your digestive tract. Crohn’s disease (CD) is a long-term (“chronic”) disease that causes all or part of the bowel (gastrointestinal [GI] tract), where food is digested in the body, to become severely inflamed (red and swollen). Crohn’s disease causes sores (ulcers) in the bowel. It is one of the two most common conditions associated with inflammatory bowel disease, the other being ulcerative colitis.

These two conditions should not be confused with irritable bowel syndrome (IBS; also called “spastic colon” or “nervous colitis”), which is a disorder that affects the muscle contractions of the colon. Irritable bowel syndrome does not involve intestinal inflammation and is a much less serious disease than CD or UC. But the symptoms are very similar, which often leads to misdiagnosis.

Crohn’s disease affects all the layers of the bowel wall – causing inflammation and swelling, as well as ulcers. In turn, this irritation may lead to bleeding. It also prevents the bowel from absorbing nutrients from food.

What Causes Crohn's disease?

Scientists do not yet know what causes Crohn’s disease (CD). They suspect that CD inflammation may be caused by a combination of an overactive immune system, environmental factors, the microbiome (bacteria in the colon) and a person’s own genetics. It is not clear what is the direct cause of the inflammation or what causes some people’s immune systems to “go into overdrive” trying to protect the body. One way the immune system tries to protect the body is through inflammation, and the immune systems of people with CD seem to produce over-reactive, poorly controlled inflammation in the GI tract. Scientists believe that once the CD patient’s immune system is “turned on”, it does not know how to properly “turn off”. As a result, inflammation damages the bowel and causes CD symptoms. This failure of the immune system to “turn off” is why the main goal of medical therapy for CD is to help patients regulate their immune system.

While the causes of CD are not known, there is agreement about what does not cause CD. Scientists no longer believe that diet and stress can cause CD. However, stress, certain foods or inadequate nutrition may aggravate symptoms, so easing stress, maintaining a proper diet and good nutrition can really help to reduce the frequency and severity of CD symptoms.

Approval code is A11755626

Scientists suspect that genes may play a role. It is not yet completely understood how or why certain genes or changes in genes are associated with CD, but it is a major focus of current research. People who have a parent, sibling or child with CD have a much higher risk of developing it themselves
Normally, the immune cells protect the body from infection. In people with CD, however, the immune system mistakes food, non-harmful bacteria and other things that are supposed to be in the bowel for substances that pose a threat. In response, it attacks the bowel lining and produces chronic inflammation. This inflammatory reaction continues without proper control, which then damages the bowel wall. When the bowel wall is damaged, CD symptoms occur, such as diarrhoea and abdominal pain.

Risk factors are personal characteristics that are known to be associated with a greater likelihood of having a disease or condition. But these risk factors, such as age or where you live, do not necessarily cause CD. Also, absence of a risk factor may not mean protection from CD.

Risk factors may include:


There is good evidence that the younger you develop the disease, the more aggressive it will be. It is also thought that if you develop the disease early in life, genetics are likely playing an important causative role. If disease onset is later in life, it is thought to be more due to environmental factors.

Isotretinoin acne medication use

Isotretinoin is an oral medication sometimes used to treat scarring acne that does not respond to other treatments. There is conflicting information as to whether isotretinoin use alone or in combination with antibiotics can increase the risk of CD. Some studies have suggested a possible link, while other studies have found no such evidence.

Cigarette smoking

Smoking has been associated with an increased risk of developing CD and also worsening of CD (flare-ups). Smoking also aggravates pain and other symptoms and increases the risk of complications. If you already have CD and still smoke, quitting may improve symptoms. Talk to your doctor about the many available smoking cessation options and support programmes.

Some pain relievers

Ibuprofen, naproxen and Aspirin have been shown to cause sores in the lining of the GI tract (gastrointestinal ulceration) and may make CD worse. Paracetamol poses a much lower risk. Discuss the use of any pain medication with your doctor.


Inflammation of the appendix that is severe enough to require an appendectomy may increase the risk of developing CD within five years after having your appendix out.

What Are the Symptoms of Crohn's Disease?

People with CD suffer a wide range of symptoms, most of them mild to moderate, depending on which part of the colon is affected. The disease is usually relapsing and remitting, which means that there can be periods of disease flare-up (active disease) and remission (temporary end to the medical signs and symptoms).  If you have CD, you may experience any or all of the following symptoms:

  • Diarrhoea (sometimes bloody)
  • Stomach cramps or pain
    o     Where the pain is felt depends on which part of the bowel is affected. The last part of the small bowel (ileum) is the part most likely to have inflammation and scarring.    
            Consequently, a common area of pain is the lower right side of the abdomen – first time pain here is sometimes mistaken for appendicitis. A sudden change or worsening of pain may indicate a complication (see below), so you should speak to your doctor immediately if one is suspected.
  • Unexplained weight loss
  • Fever
  • Dehydration
  • Failure to grow (in children)
  • Fatigue
  • Loss of appetite

The symptoms can be exhausting and may also reduce your appetite. Diarrhoea, cramping and pain can even become worse when you eat because of the increased intestinal activity afterwards. But Crohn’s disease is not the same in everyone. The severity of symptoms varies depending on the level of immune system activity and which areas of the bowel are affected. And symptoms may change over time.

Call a doctor straight away if you have been diagnosed with CD and you have one or more of the following symptoms, because your condition may have worsened:

  • Fever over 38.3°C  (101°F) or shaking chills
  • Lightheadedness, passing out or rapid heart rate
  • Stools that are almost always bloody
  • Severe dehydration, such as passing little or no urine for 12 or more hours
  • Severe stomach pain or severe pain and bloating
  • Evidence of pus draining from the area around the anus, or pain and swelling in the anal area
  • Repeated vomiting
  • Not passing any stools or gas
Are There Other Complications?

The severity of Crohn's disease (CD) symptoms can differ widely from person to person and depends on many factors including how much of the colon is affected. The digestive system is the part of the body that is affected most directly, but complications can potentially affect other parts of the body as well.

  • Bowel blockage: The most common complication of CD is blockage of the bowel. This happens when there is a narrowing (stricture) due to scar tissue that has formed in the wall of an inflamed part of the GI tract. Sometimes the narrowing can cause difficulty in food passing through (a blockage).
  • Ulcers: Chronic inflammation can lead to open sores (ulcers) anywhere in your GI tract, including your mouth, ileum (the part of the GI tract leading to the anus); in the genital area (perineum) and around the anus. These ulcers can be very uncomfortable and in the case of Crohn’s, may sometimes bleed.
  • Fistulas: A fistula is an abnormal connection between different parts of your bowel, between your bowel and skin, or between your bowel and another organ, such as the bladder or vagina. When internal fistulas develop, food may bypass areas of the bowel that are necessary for absorption. With CD, an external fistula can cause continuous drainage of bowel contents to your skin. In some cases a fistula may become infected and form an abscess – this can be life threatening if left untreated. Fistulas around the anal area (perianal) are the most common.
  • Anal fissure: Anal fissures are cracks, or clefts, in the anus or in the skin around the anus where infections can occur. They are often associated with painful bowel movements and can lead to a perianal fistula.
  • Malnutrition: Diarrhoea, abdominal pain and cramping may make it difficult for you to eat or for your bowel to absorb enough nutrients to keep you properly nourished. Anaemia is common in people with CD.
In addition to inflammation and ulcers in the bowel, CD can cause problems in other parts of the body, such as arthritis, inflammation of the eyes or skin, clubbing of the fingernails, kidney stones, gallstones and, occasionally, inflammation of the bile ducts. People with long-standing CD may also develop osteoporosis, a condition that causes bones to become weak and brittle.
Lifestyle Options

For most people, regardless of having Crohn’s disease (CD) or not, exercise, healthy eating and good sleeping habits are recommended. A healthy lifestyle can lead to an enhanced quality of life for most people. Talk to your doctor before making any lifestyle changes.

While diet is not thought to cause CD, people experiencing symptoms of the disease often find some foods aggravating. It may be helpful to keep (and regularly review) a food diary to better understand how your body is reacting to various foods. Many people find soft, bland foods make them feel better than spicy ones. Several small meals may work better then two or three large ones. If you are lactose intolerant, you may want to avoid dairy products.

In addition, chronic diseases like CD tend to increase the body’s energy needs. Since CD can cause a loss of appetite, staying nourished may take extra effort. In general, it is best to maintain a high-quality, well-balanced diet with ample fluids. Working with a registered dietician may be beneficial.

Even light exercise, especially when done regularly, can help reduce stress, improve mood and normalise bowel function.
Complementary Therapy Options

Vitamins and probiotics

As long as their own doctors agree, people with Crohn’s disease (CD) may benefit from vitamin supplements as well as the introduction of “good” bacteria into the intestine.

Mind-body medicine

People with CD may want to manage stress by using methods that focus on the connection between emotions, the body and individual health. Examples include tai chi, biofeedback, hypnosis, yoga and meditation.

Medical Treatments

The goals of medical treatment for Crohn’s disease (CD) are:

  • Absence of symptoms (achieving remission)
  • Preventing flare-ups of disease (maintaining remission)
  • Improving personal quality of life
  • Healing the gut

Medications: The goal of treating CD is to decrease or stop the inflammation. The type of medication that is prescribed depends on the severity of the disease. Common medications that can decrease inflammation are corticosteroids, immunomodulators (e.g. azathioprine, methotrexate, mercaptopurine), and drugs known as biologics, which target specific pathways believed to be involved in the disease. Other medications may include:

  • Antibiotics to prevent or control infection
  • Aminosalisylates
  • Anti-diarrhoeal medications
  • Pain relievers, including paracetamol
  • Iron supplements to control anaemia

Surgery is usually used an option after medical treatment fails. While no one wants to have an operation, sometimes it is the only way to control symptoms when medication is no longer effective.

Surgery options for Crohn’s disease

Surgical options for CD vary and depend on the amount of inflammation in the bowel. If surgery is an option talk to your doctor about what surgery is right for you. Surgeries often used in CD are:

  • Strictureplasty: dilation of narrowed parts of the bowel without removing any tissue
  • Surgery for abscesses: drainage or removal of the abscess
  • Surgery for fistulas: removal of the fistula
  • Resection: removing portions of the bowel
  • Colectomy: removing the colon
  • Proctocolectomy: removing the colon and rectum

Please note that the information on this website should not be used as a substitute for seeking medical advice or treatment from a doctor. You should not use this information to diagnose or treat a medical condition or health problem. Speak to your doctor if you have any questions about your medical condition, symptoms or treatment options.


Crohn's & Colitis UK ; a leading UK charity

The Crohn’s & Colitis Foundation of America (CCFA) is the leader in research, education and patient support for IBD (Crohn’s disease and ulcerative colitis).

The Mayo Clinic is a worldwide leader in medical research and education. This website has complete information on diagnosis, treatment, research and lifestyle recommendations for IBD. Search inflammatory bowel disease, Crohn’s disease or ulcerative colitis on the Web site.


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