The symptoms of Crohn's disease vary according to its site, (i.e. small or large intestine) and severity. However, the following features occur in most cases.

1. Diarrhoea - sometimes, but not always, with blood.

2. Abdominal pain and tenderness over the intestine, often more severe in the right iliac fossa.

3. Weight loss, and in children failure to grow.

4. Fever.

5. Tiredness.

6. Sores and abscesses around the anus, which have a discharge. These may be the first signs of the disease in some patients.

7. Other symptoms not involving the intestine may occur:

I. Sore mouth due to ulcers on the tongue or inside the cheek
II. Painful, inflamed eyes (uveitis)
III. Painful, stiff or swollen joints, e.g. arthritis, ankylosing spondylitis
IV. Sore, red lumps on the skin (erythema nodosum)