Diagnosis is hard because IBS can have mild or severe symptoms. IBS comes and goes during a patient's lifetime. Moreover, early IBS symptoms and inflammatory bowel disease symptoms are similar, namely pain, constipation and diarrhoea.
The proposed causes of IBS are stress, anxiety and a poor diet. The intestine in IBS sufferers contracts more vigorously after eating, which anti-spasmodic drugs can counteract. Other approaches are a no-milk high-fibre diet and painkillers.