Consider features which may suggest an underlying cause - travel abroad, laxative use, other drugs, chronic fatty diarrhoea, previous abdominal surgery, family history of coeliac disease or inflammatory bowel disease, diet and relationship of symptoms to eating, excessive alcohol intake, abdominal pain, weight loss, anxiety, palpitations, tremor, lifelong history of constipation, immunocompromised person, features of systemic disease, systemic illness and rashes.