Prescribing in lactose intolerance and how to identify lactose free medicines.

Helen Davis, Director, North West Medicines Information CentrePublished

Why lactose in medicines is important for healthcare professionals to consider, and how to check lactose content and identify lactose free medicines.

Lactose in medicines

Lactose is widely used in tablets and capsules where it acts as a diluent or filler. It may also be found in dry powder inhalers, lyophilized products, sugar coating solutions and some liquid preparations.

Published reports are rare, but lactose in medicines may cause people with lactose intolerance discomfort and therefore affect whether they take their medication. To avoid lactose, different routes of administration, brands or alternative medications may be necessary.

Healthcare professionals should be aware of the possible effects of lactose in medicines. The presence of lactose in a medicine, together with medical assessment, should be considered as a possible underlying cause of apparent gastrointestinal (GI) intolerance to medications.

Checking the lactose content of medicines

Healthcare professionals can reassure patients that the lactose content of oral medicines is generally small (less than 2g per day) compared to the amount of lactose in food, particularly dairy products.

Unless an adult has severe lactose intolerance, it is unlikely that lactose in a conventional oral solid-dosage form (like tablets or capsules) will cause severe GI symptoms.

For people with severe lactose intolerance, the healthcare professional should determine the lactose content of any medicines before prescribing.

How to find the lactose content of medicines

You can check product information for licensed medicines using the Summary of Product Characteristics (SmPC) or Patient Information Leaflet (PIL), to see if lactose is listed.

SmPCs and PILs for most UK medicines are available on the emc website or the Medicines and Healthcare products Regulatory Agency (MHRA) Products website Manufacturer’s websites may also have SmPCs and PILs.

To determine the exact amount of lactose in a medicine you will need to contact the relevant manufacturer of the product, since this detail is not usually provided in the product information. The amount of lactose may vary by manufacturer, product, formulation, or strength.

For ‘Specials’ and unlicensed medicines, where an SmPC or PIL may not be available, you will usually have to contact the manufacturer directly.

To identify lactose-free products you can carry out an advanced search of SmPCs on the emc website.

Follow these steps to find lactose free products on the emc

What is lactose intolerance

Lactose is a natural sugar found in animal milk that is broken down in the small bowel by the enzyme lactase. People with lactose intolerance have reduced or absent activity of this enzyme. This means they find it more difficult to digest lactose in milk or milk containing products.

When undigested lactose reaches the colon it draws in fluid and is fermented by enteric bacteria. This may result in painful and persistent GI symptoms such as abdominal bloating, wind, diarrhoea, nausea and abdominal cramps.

Lactose intolerance is not the same as cow’s milk allergy, although some symptoms do overlap.

When do symptoms occur

Not everyone with a lactase deficiency has symptoms of lactose intolerance.

Most people with lactose intolerance do not need a severely restricted or lactose-free diet.

Symptoms can vary depending on the amount of lactose ingested, a person’s ability to digest lactose and the amount and type of colonic bacteria.

In people with the most common type of lactase deficiency (primary) the development of symptoms depends on how much lactose they need to ingest before the available lactase is saturated.

Types of lactose intolerance

There are several types of lactose intolerance or lactase deficiency (hypolactasia) and the condition may be temporary or permanent.


  • The most common form. Occurs as affected individuals begin to produce less lactase as they age. Usually starts at around 2 years of age, but symptoms may not occur until years later, if at all.


  • Occurs following injury to the small bowel either from infection (such as gastroenteritis) or diseases that impair lactase production such as  inflammatory bowel disease or coeliac disease.


  • Less common types are congenital lactase deficiency or developmental lactase deficiency.

Further information

More detailed information on lactose intolerance is available from a variety of online sources. Examples include;

For healthcare professionals

For members of the public