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Crohn's disease - symptoms, diagnosis, treatment

Crohn’s disease is a chronic (long-term) inflammatory disease of the bowel (intestines). It primarily affects the small and large bowel, but can occur anywhere in the digestive tract. The inflammation causes uncomfortable and bothersome symptoms and may result in serious damage to the digestive tract. Abdominal pain, diarrhoea and weight loss are the most obvious symptoms. Making a definitive diagnosis is difficult, possibly requiring many different tests performed over a long period of time.

General information

Crohn’s disease is one of the two major types of inflammatory bowel disease (IBD), the other being ulcerative colitis. The main difference between the two conditions is that, whereas Crohn’s disease can affect any part of the digestive tract, ulcerative colitis affects only the large bowel and the rectum.

Both Crohn’s disease and ulcerative colitis are believed to be autoimmune diseases, where the body reacts against its own tissues.

The number of people with Crohn’s disease in New Zealand is not known but it has been estimated that nearly 17 in every 100,000 people in Canterbury have the disease, which is one of the highest reported rates in the world. Regional population differences may partially explain the high rate, as Crohn’s disease is more common in Caucasian people than in Maori or Pacific Island people.


The precise cause of Crohn’s disease is unknown. There are, however, several established risk factors, including the following: 

  • Family history (genetics)
  • Smoking
  • Use of oral contraceptives
  • Ethnicity
  • Environment
Interaction between the predisposing genetic factors (making a person more inclined to develop the condition), environmental factors, host factors (eg: a person’s immune system function), and a triggering event (eg: bacterial infection) may be responsible for the development of the disease.
Although diet may affect the symptoms in patients with Crohn's disease, it is unlikely that diet is responsible for the disease.
There is a clear genetic predisposition for Crohn’s disease. People with a relative who has the condition have 10-times higher likelihood of developing the disease than that of the general population. People are 30-times more likely to develop the condition if the relative with Crohn's disease is a brother or sister. It is also more common among relatives of people with ulcerative colitis.
Environmental factors, especially cigarette smoking, are also clearly involved in this disease. Tobacco smoking doubles the risk of both initial and recurrent Crohn’s disease.
Improved food storage and reduced food contamination may also contribute to the development of Crohn’s disease. This is the so-called ‘hygiene hypothesis’. It proposes that the reduction in abdominal infections in developed countries has resulted in altered immune responses in the digestive tract. Bacterial infections that otherwise might only cause short-term disease instead may trigger a massive inflammatory response in the digestive tracts of susceptible individuals.

Signs and symptoms

Most people with Crohn’s disease are diagnosed during late adolescence and early adulthood (15-30 years of age), with a second spike in numbers occurring between the ages of 60 and 70 years, mainly in women.
Symptoms depend on the location and severity of the inflammation. Unpredictable symptomatic flare-ups and remissions characterise the long-term course of the disease.

Typical symptoms in a person with Crohn’s disease are chronic diarrhoea and abdominal pain and tenderness. Other Crohn’s disease symptoms include: 

  • Rectal bleeding
  • Fever
  • Weight loss, and loss of appetite
  • Nausea, vomiting
  • Malnutrition, and vitamin deficiencies
  • Tiredness, lethargy
  • Bone loss (osteoporosis)
  • Depression, anxiety (associated with coping with the condition)
  • Stunted growth in children (which may occur many years before digestive symptoms appear)
Additionally, the area around the anus may be affected by ulcers, abscesses, fissures (small ulcerated cracks) or fistulas (small abnormal holes in the wall of the intestines or rectum).


Crohn's disease is suspected in people who have experienced symptoms of abdominal pain, diarrhoea, and weight loss over a period of weeks or months. There is no single test that can establish the diagnosis of Crohn's disease with certainty, and Crohn's disease often mimics other conditions. For these reasons, it may take time and several investigations to arrive at a definite diagnosis of Crohn’s disease.
Proper clinical separation from ulcerative colitis is important because the two conditions are treated differently. Ulcerative colitis causes inflammation only in the lower digestive tract (large bowel, rectum, or both), while Crohn's disease may cause inflammation anywhere in the digestive tract, including the mouth and anus. Another difference is that, in Crohn’s disease, inflamed segments of the intestine may be separated by healthy segments, giving the condition characteristic ‘skip lesions’.
The first part of the diagnosis involves the doctor taking a full medical and family history. A thorough physical examination is also conducted. Blood tests may be ordered to look for a low blood count (anaemia) that may result from rectal bleeding, to measure the severity of inflammation, and to detect vitamin or mineral deficiencies. A bowel motion specimen may be needed to exclude infection as the cause of the symptoms being experienced.
Most people require part of their intestine to be examined, either by direct or indirect inspection. Direct inspection is carried out by endoscopy - a procedure in which a small flexible tube (endoscope) with a fibre-optic camera at its tip is inserted through the anus (colonoscopy or sigmoidoscopy) or mouth (gastroscopy). The doctor is able to see the lining of the rectum and colon on a television screen and can look for signs of inflammation that may indicate Crohn’s disease. Small samples (biopsies) of the lining of digestive tract can be taken for analysis. Endoscopic visualization and biopsy are essential in the diagnosis of Crohn’s disease.
Indirect inspection involves the use of computerised tomography (CT) scan, which is a type of computerised X-ray, and barium X-ray studies, in which a chalky substance (barium) is swallowed or administered into the rectum and colon and X-rays taken. The barium, which can be seen on the X-rays, improves the contrast of the X-ray images.


Because there is no cure for Crohn’s disease the primary goals of treatment are the following: 

  • To achieve the best possible control of the inflammation with the fewest adverse effects from medication
  • To permit life to be lived as normally as possible
  • In children, to promote growth with adequate nutrition

Medication is frequently effective in calming down flare-ups for long periods, and surgery can bring prolonged relief of symptoms that are not controlled with the use of medication.


Medications can relieve the symptoms of Crohn’s disease and reduce the chances that complications develop by bringing the inflammation under control. Most importantly, controlling the inflammation gives the digestive tract an opportunity to heal.
Because Crohn’s disease is a chronic condition, many people will need to take medications for long periods of time, either to bring the disease under control or to maintain remission once the symptoms have disappeared.
A combination of medications is often required. The choice of medications used depends on the location of the inflammation, the severity of symptoms, and whether the aim is to treat a flare-up or to prevent further flare-ups. The types of side effects experienced, which can vary for different people, may also be a factor in the choice of medication used.
Four main categories of medication are used to treat inflammation in Crohn’s disease:
Anti-inflammatory agents: aminosalicylates, such as mesalazine (Pentasa) and sulphasalazine (Salazopyrin), are usually prescribed for mild-to-moderate Crohn’s disease and are used to prevent flare-ups; corticosteroids, including budesonide (Entocort) and hydrocortisone acetate (Colifoam), are usually prescribed in short courses for active moderate-to-severe Crohn’s disease. These medications act by reducing inflammation. The aminosalicylates and corticosteroids can be taken by mouth (orally) and into the rectum (as an enema or suppository).
Antibiotics: such as ciprofloxacin (Cipflox), are used in the treatment of mild-to-moderate disease. It is thought that antibiotics work by altering the bacterial population of the intestine. They may also have an effect on the immune system.
Immunomodulators: including methotrexate (Methoblastin) and azathioprine (Imuran) are sometimes used to treat moderate-to-severe Crohn’s disease, disease that does not respond to corticosteroids, and to prevent flare-ups. These medications work by suppressing the immune system.
Disease-modifying agents: such as infliximab (Remicade) and adalimumab (Humira) are used in the treatment of active moderate-to-severe Crohn’s disease that has not responded to other medications. These medications act by disrupting the inflammatory process. Their use is somewhat restricted because they are expensive.
Other medications may be prescribed to address specific symptoms such as chronic diarrhoea and abdominal cramps.


Unlike ulcerative colitis, Crohn’s disease does not have a surgical cure. Most people with Crohn’s disease will, however, require surgery at some point in their lifetime either to control symptoms or to correct complications of the disease. 
Major surgery, called resection, may be needed to remove severely inflamed or damaged portions of the small or large intestines. Abscesses or fistulae around the anus can be treated using local surgical drainage procedures.
People can be free of disease and symptoms for some time, often years, after a resection, and enjoy a marked improvement in their quality of life. In many people, however, Crohn's disease eventually returns, affecting previously healthy digestive tract. Half of patients can expect to have a recurrence of symptoms within four years of surgery. Certain drugs (eg: mesalazine) can reduce the chance of the disease returning after surgery.


Crohn’s disease present in the small intestine can impair the digestion and absorption of essential nutrients from food passing through the digestive tract. During flare-ups, many people also try to avoid eating in order to prevent further symptoms. The resulting malnutrition worsens the tiredness and fatigue and can eventually lead to weight loss.
A well-balanced and nutritious diet is essential for anyone with Crohn’s disease to prevent malnutrition and maintain good health. A healthy diet is even more important for growing children and adolescents with Crohn’s disease who may experience delayed growth or pubertal development without adequate nutrition. Vitamin (eg: vitamin D) and mineral (eg: iron and calcium) supplements might be necessary in some people. Fibre supplementation may be beneficial in some people with Crohn’s disease – fibre helps the healing of inflamed regions of the digestive tract.
Diet also plays a role in the symptoms of Crohn’s disease. There is no specific Crohn’s disease diet that is recommended for all people, but most people with the disease are aware of what foods make their symptoms worse and what foods lessen their symptoms. Some people find that eating smaller portions at meal times helps to lessen some symptoms.
In a of study of Caucasian New Zealanders with Crohn’s disease, foods most often considered to be beneficial for symptoms included white fish, salmon and tuna, gluten-free products, and boiled potatoes and sweet potatoes. Foods most often considered to make symptoms worse included grapefruit, nuts, chilli or chilli sauce, cream, salami, high energy drinks and beer. It was not possible to identify specific foods that should be avoided by all people with Crohn’s disease.

Further support

For further support and information get in touch with Crohn’s & Colitis New Zealand or visit their website.

Crohn’s & Colitis New Zealand Charitable Trust
Phone: 0800 ASK IBD (0800 275 423)


Crohn’s & Colitis New Zealand (2011) Crohn’s Disease (PDF). Wellington: Crohn’s & Colitis New Zealand Charitable Trust.
Gearry, R.B., Day, A.S. (2008) Inflammatory Bowel Disease in New Zealand Children – a Growing Problem. NZ Med J;121(1283):5-8.
O'Toole, M.T. (Ed.) (2012) Crohn’s Disease. Mosby’s Dictionary of Medicine, Nursing & Health Professionals (13th ed.). St Louis: Elsevier Mosby.
Schoenfeld, A, Wu, G.Y. (2010) Crohn’s Disease. New York: WebMD LLC.
Triggs, C.M., et al (2010) Dietary factors in chronic inflammation: food tolerances and intolerances in a New Zealand Caucasian Crohn’s disease population. Mutation Research 690(1-2):123-38.


Created: May 2013


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