The symptoms of IBD vary depending on the area of involvement; extent and severity of disease, and whether any complications have arisen, but abdominal pain, diarrhoea, the passing of blood and fatigue are commonly experienced.

Other signs and symptoms may include nausea and vomiting, constipation, a low-grade fever, weight loss and nutritional deficiencies.

In Crohn's disease, symptoms usually have a gradual onset over many months or years, whereas ulcerative colitis tends to be develop more quickly.

Sometimes symptoms occur from several other conditions (some inflammatory) that develop outside of the IBD, although not everyone will have these problems. These affect the skin (mouth ulcers, tender red bumps or blisters on the lower legs), the joints (pain, swelling and stiffness) and the eyes (redness, tenderness and ocular changes).

The liver and bile ducts can also be affected, but symptoms are not usually present until problems have reached an advanced stage.