Crohn's disease

Crohn’s disease is one type of a condition called inflammatory bowel disease (IBD).
New Zealand has the third highest rate of inflammatory bowel disease in the world with the number increasing at an alarming rate. It is estimated to affect 15,000 New Zealanders.

What is Crohn's disease?

It is a lifelong condition in which parts of the digestive system become inflamed. Crohn’s disease can affect any part of the gastrointestinal tract from the mouth to the anus. The wall of one or more segments of the gastrointestinal tract becomes thickened, inflamed and swollen.

It most frequently affects the end of the small intestine where it joins with the colon (large intestine). The next most common place of inflammation is the anus. It is a disease that may reappear intermittently with flare-ups between intervals of relative quiescence.

What are the symptoms of Crohn's disease?

Symptoms arising from this disease will vary both in intensity and character and they are very much dependent upon which part of the body has been affected. Most of the symptoms from Crohn’s disease are due to the affects of inflammation.

As a chronic disease, Crohn’s frequently runs a kind of ‘relapsing and remitting’ course meaning there may be long periods of good health alternating with episodes of symptoms lasting for weeks or months.

When the disease is active symptoms can include:

  • Bleeding in the bowel motion
  • Disturbance in bowel movements, such as diarrhoea, constipation, or feeling that your bowel doesn’t empty completely
  • Abdominal pain
  • Weight loss
  • Tiredness
  • Anaemia
  • Pain or drainage near or around the anus due to inflammation from developed abcesses (fistula)
  • Nausea and vomiting

Patients who have non-intestinal Crohn’s disease may present with severe mouth ulcers, difficulty swallowing, indigestion, sore eyes, painful and swollen joints or tender skin rashes.

What causes Crohn's disease?

Despite a great deal of research, the cause of Crohn’s disease remains uncertain. It is not an infectious illness in that it cannot be passed from people with Crohn’s disease to previously healthy individuals. It is thought that individuals have a genetic predisposition to Crohn’s disease and that some sort of “trigger”, such as something infective, perhaps a virus or bacterium, initiates the disease process later in life. Environmental factors also appear to play a role as well as additional risks, the most important of which is smoking.

Crohn’s Disease most commonly affects young adults, but it can affect teenagers and even younger children. A second peak in incidence occurs adults the age of 60. Men and women are equally affected.

Smoking and Crohn's disease

The negative effect of smoking on Crohn’s disease can not be overemphasised. Smoking makes Crohn’s disease more aggressive and more difficult to treat. Patients who smoke are more likely to develop complicated Crohn’s disease, are more likely to need an operation and have early recurrence of their Crohn’s disease after operation.

Smoking makes all medical treatments less effective. The positive benefits of taking a drug like azathioprine can be completely negated by smoking.

Stopping smoking is the single most important thing a patient who has Crohn’s disease can do for their health. Stopping smoking of course has many other important health benefits as well!

For support and guidance on giving up smoking visit

Diagnosing Crohn's disease

Crohn’s disease is diagnosed by a combination of listening to your symptoms, physical examination, and investigation of the bowel by x-ray and/or colonoscopy and biopsies. A pathologist examining a sample of inflamed Crohn’d disease tissue under the microscope may confirm the diagnosis.

How is Crohn's disease treated?

The aim of Crohn’s disease treatment is to reduce the inflammation in the intestine sufficiently to allow normal digestive function to occur. Unfortunately, no known treatment, either medical or surgical, can be guaranteed completely and permanently to eliminate Crohn’s disease. However, medical treatment is frequently effective in settling down flare-ups of the disease for long periods, and surgery often brings prolonged relief of symptoms for those who are not managed with medical treatment.

The management of Crohn’s disease falls between two different branches of medicine, Gastroenterology and Colorectal Surgery. A gastroenterologist is a specialist physician who manages diseases of the digestive system whilst a colorectal surgeon manages these diseases too when they require a surgical solution. 

Non-surgical treatments

A group of drugs called aminosalicylates are often used, often with good effect. These drugs are related to the aspirin that is commonly used and they settle inflammation from within the gut.

More powerful suppressors of the immune system may sometimes be required. These include steroids (prednisolone and hydrocortisone), immune suppressors or immune modulators (azathioprine, 6-mercaptopurine, methotrexate) and biological therapy (infliximab).

Antibiotics such as metronidazole are used to reduce the bacteria that drive the inflammation or to treat abscesses.

A gastroenterologist is very familiar with these drugs and would advise any patient in great detail about them.

Surgical treatments for Crohn's disease

Surgery remains an important part of the management of Crohn’s disease. It is rarely needed from the outset but rather when medical management with drugs has been tried and failed.

When complications from Crohn’s disease occur e.g. fistula, abscess, perforation, obstruction etc, colorectal surgeons are required to address this. Occasionally it is necessary to remove a portion of the intestine which is badly affected by Crohn’s disease, but your Surgeon will endeavour to preserve as much intestine as possible if this becomes necessary.

Your surgeon would very carefully advise you of the role of any surgery, the effects that this will have upon you and any side-effects or consequences of the surgery that has been necessary.

Dietary treatment for Crohn's disease

Crohn’s patients often need the help of a dietitian to ensure that they are getting adequate calories and food constituents to ensure health. There is no specific diet for Crohn’s disease, but often a reduction in fibre in indigestible food will help. This is known as a “low residue” diet.

At Intus, our consultant dietitian, Stephanie Brown, has specialist interest in gastrointestinal health, including Crohn’s disease. Stephanie successfully provides patients with effective and practical strategies to manage symptoms.

Find out more about our Dietary services.

Frequently asked questions

No item of the normal Western diet and no food additives have been found to cause Crohn’s disease, so there is no logical reason for specific exclusion diets. In general, people with Crohn’s disease will benefit from the high nutritional content of a varied and ample diet. This should approach as near as possible to a normal diet, though individuals may wish to avoid specific foods (e.g. nuts) which they know from personal experience will worsen their symptoms.

An acute disease is one which runs a short sharp course like, for example, the ‘flu’. A chronic disease can give trouble over a number of years, although there may be long periods of good health alternating with episodes of symptoms lasting for weeks or months. Crohn’s disease frequently runs this kind of ‘relapsing and remitting’ course. Unfortunately, no doctor can predict when a relapse is likely to occur, nor can they guarantee that the future will be trouble-free, even when all visible evidence of Crohn’s disease has disappeared following medical or surgical treatment.

No, not in the same sense as a characteristic like colour blindness or a disease like haemophilia. However there seems to be some inherited contribution to the development of the disease in that a minority of patients have one or more close relatives with Crohn’s disease. If you have the disorder there is a 10-25% chance that a further family member (child/parent/sibling) will also have or develop Crohn’s disease. The risk that a child will get Crohn’s disease if one of their parents has it is only about 1-2 in a hundred!

Find out more:

The Canterbury Crohn’s and Colitis Support Group are very active and have a large amount of information.

They also provide a very useful handbook for people living with IBD. You can download the handbook here.