Loperamide is the most common drug taken for diarrhoea but it can cause abdominal pain and constipation in some people. Bile acid sequestrants such as Questran can mop up irritant bile acids that are not well re-absorbed in people with IBS-D and can be very useful when Loperamide is not tolerated, but they have to be taken before meals and balance the dose with the size of the meal as well as the response of the symptoms.  A diet low in fructose (fruit sugar) or lactose (milk sugar) can be very effective in people who do not absorb these sugars well.