This is a condition caused by abnormal muscular contractions affecting the large or small intestine. Symptoms include pain and discomfort in the abdomen, which change location, disturbed bowel movements with diarrhoea, then normal movements or constipation, heartburn and a bloated feeling due to flatulence. These symptoms are produced without any signs of structural disorder or obvious cause.

Sometimes, symptoms develop after a gastrointestinal tract infection. Stress and anxiety are believed to be a contributory factor and certain foods or drinks may worsen the condition in some people.