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What to consider when prescribing for lactose-intolerant adults

UK Medicines Information summarises the evidence for this frequently asked question:

Individuals who have lactose intolerance have reduced or absent activity of the enzyme lactase. In such patients, lactose can cause painful and persistent gastrointestinal (GI) symptoms (abdominal bloating, flatulence, diarrhoea, nausea and abdominal cramps) when it is ingested.

The lactose content of oral medicines is generally small in comparison with the amount present in some dietary substances;  most pharmaceuticals provide less than 2g of lactose per day. Therefore, unless a person has severe lactose intolerance, it is unlikely that lactose in a conventional oral solid dosage form will cause severe GI symptoms. Findings from one double-blind randomised controlled study suggest that lactase deficiency should not be considered a contraindication to the use of medicines containing 400mg of lactose or less per dose.

The authors of a UK study suggest that the lactose content of medicines should be considered in addition to dietary sources in the management of patients with lactose intolerance because patients often take more than one medicine and cumulative exposure to lactose can occur.

For patients with severe lactose intolerance, the lactose content of any medicines should be determined before they are prescribed. The amount of lactose may vary by manufacturer, product, formulation and strength.

Although there are few published case reports, some patients may experience discomfort when taking lactose-containing medicines and this can affect adherence to treatment — changing the route of administration, the brand or using an alternative option may be necessary. Liquid preparations of most medicines are lactose-free and may provide an alternative option in some cases.

This FAQ is taken from a “Medicines Q&A” produced by UK Medicines Information. The full document, including references, is available from (prepared June 2013). NHS Evidence is provided by the National Institute for Health and Care Excellence and incorporates content formerly held in theNational electronic Library for Medicines 


Citation: Clinical Pharmacist DOI: 10.1211/CP.2013.11129489

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