What is Crohn’s disease?

Crohn’s disease starts with an abnormal response by your immune system, which causes the inflammation that can lead to Crohn’s symptoms

Crohn’s disease starts with an abnormal response by your immune system, which causes the inflammation that can lead to Crohn’s symptoms

When your Crohn’s disease is active, the signs and symptoms could include:

  • Abdominal pain – intermittent and often cramping. The abdomen may be sore when touched. Abdominal pain may feel like a dull, constant ache depending on the location of inflammation.

  • Diarrhoea – some people have diarrhea many times a day and need to wake up at night to go to the bathroom.

  • Fever – a high fever may indicate a complication.

  • Unintended weight loss – ongoing symptoms, such as vomiting or diarrhoea, can lead to substantial weight loss.

Your Crohn’s disease symptoms may range from mild to severe. They may develop gradually or seem to come on without warning. They may even seem to go away (be in remission) for a little while, then return.

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:


  • About 5% to 20% of patients have a close relative with either Crohn’s disease or ulcerative colitis3

  • A person’s risk of having Crohn’s disease is about 10X greater if they have a relative with it3

  • If the relative with Crohn’s disease is a brother or sister, a person’s risk of having it is 30X greater3

  • 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

Diagnosing Crohn’s disease – it’s not easy

Crohn’s disease has always been difficult to diagnose, because symptoms vary from patient to patient, and because it can be similar to other conditions. Doctors evaluate the patient’s history and physical exams, as well as one or more laboratory tests such as blood tests, stool tests, barium X-ray, colonoscopy, biopsy, computerised tomography, and video capsule endoscopy. However, with more up-to-date methods used by gastroenterologists who specialize in Crohn’s disease, it may be easier to get a definitive diagnosis.

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