What is Crohn’s Disease?

Crohn’s Disease is a condition in which there is swelling, thickening and inflammation of one or more parts of the gastrointestinal tract from the mouth to the bottom (anus). Any part can be affected, but it is more common in the last part of the small bowel and colon.

Symptoms and signs of Crohn’s Disease

The symptoms of Crohn’s Disease depend on the location (where in the gut) and the spread (extent) of the swelling and inflammation in the gut. The symptoms can range from mild to severe. The most common signs and symptoms are:

  • abdominal pain and diarrhoea (most common)
  • blood and mucus in your poo (faeces)
  • unintended weight loss.

Other general signs and symptoms include:

  • loss of appetite
  • extreme tiredness
  • fever
  • vomiting and/or constipation
  • the area in and around the anus is affected by ulcers, abscesses or fistulas (small holes in the wall of the bowel or rectum).

The outlook, or prognosis, for Crohn’s Disease is different for different people and depends on which part or parts of the gut are affected and how often and how severe the flare-ups are .

With this kind of variability, it’s important to assess your Crohn’s Disease symptoms regularly with your doctor.

We’ve created an assessment tool so you can monitor your symptoms and share the results with your doctor. Track your Crohn’s disease symptoms now.

What causes Crohn’s Disease?

The exact cause of Crohn’s Disease is not fully understood but it’s thought to be a result of a combination of factors:

Genetics (family history)

  • About 5% to 20% of patients have a close relative with either Crohn’s Disease or ulcerative colitis
  • While several genes were found to be associated with Crohn’s Disease, many people who carry these genes do not develop Crohn’s Disease.


  • Immune responses in the GI tract can be due to exposure to foreign substances in the environment
  • Inflammation can also be triggered by microorganisms and intestinal bacteria
  • Certain foods can aggravate symptoms in some people, but there have been no studies to suggest that diet can either cause or treat Crohn’s Disease.

Immune system

  • Researchers believe substances in the intestines are mistaken for invading substances (antigens)
  • To combat these antigens, your immune system causes temporary inflammation, which is reduced as you regain health.

Talk with your doctor

We’ve put together a checklist that you can take along to your gastroenterologist visit to discuss symptoms and treatment options.

Download your ‘Getting ready for your gastroenterologist visit’ guide

Download your guide