Lactose intolerance

There is often confusion between cow’s milk allergy and lactose intolerance, but they are very different conditions.

Lactose is a sugar found naturally in animal milk such as cow’s milk. Lactose intolerance is caused by reduced levels of the digestive enzyme, lactase. Since lactose, the milk sugar, is not fully broken down and therefore not digested properly, it remains within the digestive tract where it is processed by bacteria in the body resulting in bloating and digestive discomfort.

There are two types of lactose intolerance:1-2

  • Primary lactose intolerance. This is rarer than secondary lactose intolerance and results from an inherited deficiency of the enzyme lactase
  • Secondary lactose intolerance. This is more common and occurs following an infection in the gut such as gastroenteritis
Symptoms of lactose intolerance2

Symptoms can include:

  • Bloating
  • Excess wind
  • Stomach rumbling
  • Stomach pain
  • Nausea
  • Diarrhoea
Diagnosing lactose intolerance2

Lactose intolerance can be diagnosed by a simple test that measures blood sugar levels before and after consuming lactose.

Management of lactose intolerance1,2

For every baby, the management of lactose intolerance can vary. As food intolerances are often managed by food avoidance or elimination it’s essential your baby maintains a full and varied diet, so always ensure you consult with a healthcare professional before any food groups are eliminated.

Primary lactose intolerance is a life-long condition and management includes:2

  • Adaptation of your baby’s diet to help identify which foods your baby can and cannot eat, and how much lactose they are able to tolerate
  • Lactose-free yoghurt and cheese

Secondary lactose intolerance can be transitory and management may include:2

  • Reducing the amount of lactose in your baby’s diet for a few weeks or months
    • If you are breastfeeding you will be able to carry on, however, if you are bottle feeding you may have to switch to a lactose-free infant formula under the guidance of your healthcare professional
  • Lactose-free yoghurt and cheese
  • After a couple of weeks, following a low lactose / lactose-free diet your baby’s gut should be sufficiently better to allow the re-introduction of lactose into their diet. However, this should only be done under the guidance of your healthcare professional

If you have any concerns, please discuss these with your
healthcare professional.


  1. Webster-Gandy J et al. (Eds) Oxford Handbook of Nutrition and Dietetics 1st edition. Oxford Publishing; Oxford 2006 pp 514-515.
  2. Great Ormond Street Hospital, 2007: Accessed 14th August 2013.

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RXANI140098 Date of preparation: March 2014