Southern Cross Medical Library

Southern Cross Medical Library

Crohn’s disease is a lifelong condition that causes inflammation in the digestive system – most commonly in the bowel.

Diarrhoea and abdominal pain are the most obvious symptoms, which can vary in severity from mild to debilitating. The condition can cause severe damage to the digestive tract over the longer term.

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 Crohn’s disease can affect any part of the digestive tract (from the mouth to the anus) while ulcerative colitis affects only the large bowel and the rectum. Crohn's and ulcerative colitis are estimated to affect around 15,000 New Zealanders.

Diagram of gastrointestinal tract 

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


The cause of Crohn’s disease is unknown. Research suggests it may involve a person’s genes, their immune system, their environment, or a combination of these things. Smoking and diet are also thought to play a role in triggering Crohn’s.

Crohn's disease is more common in people who have family members with the disease, which indicates the role genes may play in a person developing the condition. However, the majority of people who have Crohn's disease do not have a family history of the disease.

Smoking has been demonstrated to double the risk of Crohn’s disease. A diet high in fatty foods and low in fibre may also play a role in the development of Crohn’s disease, while some people find that specific foods affect their symptoms.

Signs and symptoms

Most people with Crohn’s disease are diagnosed in their teenage years or early adulthood (15–30 years of age), with a second spike in numbers occurring between the ages of 60 and 70 years.

Symptoms depend on where in the digestive tract the inflammation is happening, and its severity. Crohn’s is a lifelong condition that typically involves flare-ups followed by periods of remission where symptoms do not occur.

The main symptoms of Crohn’s disease are chronic diarrhoea and abdominal pain. Other 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).

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 may also lead to ulcers in the digestive tract and it increases the risk of bowel cancer.


There is no single test that can establish the diagnosis of Crohn's disease with certainty, as Crohn's disease can have similar symptoms to other conditions.

A doctor may suspect Crohn's disease or ulcerative colitis in a person who has had abdominal pain, diarrhoea, and weight loss over a period of weeks or months (reaching a diagnosis of one or the other is important because the two conditions are treated differently).

Blood tests may be done to look for a low blood count (anaemia, may result from rectal bleeding), measure the severity of inflammation, and detect vitamin or mineral deficiencies. A bowel motion specimen (poo sample) may be needed to test for blood and exclude infection as the cause of the symptoms being experienced.

Most people will need part of their intestine to be examined, either by direct or indirect inspection. Direct inspection is done using a small flexible tube (endoscope) with a fibre-optic camera at its tip which is inserted through the anus (this procedure is known as a colonoscopy or sigmoidoscopy) or through the mouth (gastroscopy).

The doctor is able to see sections of the digestive tract 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 may be taken for analysis in a laboratory.

Indirect inspection involves the use of computerised tomography (CT) scan or barium x-rays. In the latter procedure, barium liquid is swallowed or injected into the rectum to enhance what can be seen in the x-ray images.


There is no cure for Crohn’s disease. The primary goals of treatment are:

  • 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.


Medications can bring inflammation under control, reducing Crohn’s symptoms and possible complications of Crohn’s disease, and giving the digestive tract an opportunity to heal.

Because Crohn’s disease is a lifelong condition, many people will need to take medications for extended periods of time to bring the disease under control and then prevent symptoms from flaring up again.

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:

  • Medications that reduce inflammation. They can be taken by mouth (orally) and into the rectum (as an enema or suppository).
  • Medications that suppress the immune system
  • Antibiotics that are thought to work by altering the bacterial population in the intestine
  • Antibody-based medications that disrupt the inflammation process.

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.

Lifestyle changes

The following lifestyle changes may help control the symptoms of Crohn's disease and extend the time between flare-ups.


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 may avoid eating in order to prevent further symptoms. The resulting malnutrition worsens tiredness and fatigue, and may 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 because without adequate nutrition they may experience delayed growth or puberty. Vitamin and mineral supplements might be necessary in some people. Fibre supplementation may be beneficial in some people with Crohn’s disease — dietary fibre helps the healing of inflamed regions of the digestive tract.

There is no specific Crohn’s disease diet that is recommended for all people, but people with the disease are likely to know some foods make their symptoms worse. Some people find that eating smaller portions at mealtimes 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, energy drinks, and beer.


Smoking increases the risk of developing Crohn's disease and can make it worse in people who already have the disease. Quitting smoking can benefit overall digestive tract health and may provide other health benefits.


Stress can worsen the symptoms of Crohn's disease and may trigger flare-ups. Although it is not always possible to avoid stress, it can be managed through exercise, relaxation techniques, and breathing exercises.

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

Free phone: 0800 ASK IBD (0800 275 423)
Email: [email protected]


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O'Toole, M.T. (Ed.) (2017). Crohn’s disease. Mosby’s Dictionary of Medicine, Nursing & Health Professionals (10th ed.). St Louis, MI: Elsevier.
Ghazi, L.J. (2019). Chron disease (Web page). Medscape Drugs and Diseases. New York, NY: WebMD LLC. [Accessed: 06/07/20]
Su, H.Y., et al. (2016). Rising incidence of inflammatory bowel disease in Canterbury, New Zealand. Inflamm Bowel Dis 2016;22(9): 2238–44.
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 2010;690(1-2):123-38.

Updated: July 2020

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The purpose of the Southern Cross Medical Library is to provide information of a general nature to help you better understand certain medical conditions. Always seek specific medical advice for treatment appropriate to you. This information is not intended to relate specifically to insurance or healthcare services provided by Southern Cross.