Lactose Intolerance

Dealing with Lactose Intolerance in Babies

2 November 2021
Posted by: Chelsea

Many parents have heard of lactose intolerance and wonder both what causes it and how it can be dealt with.

Here we’ll discuss lactose intolerance in babies but as always, do please remember this is NOT qualified medical advice. If you have concerns about your baby’s health you must consult a doctor.

Note also that this is about babies and younger toddlers – older children and teenagers need to be considered separately.

What is lactose intolerance in babies?

Lactose is a complex sugar found in many sources but notably some milk and dairy produce.

Most people, including babies, have something called “lactase” in their stomachs. Lactase is an enzyme that helps us to break down the lactose in food, into forms our bodies can use for energy.

Contrary to some misconception, lactose is present in breast milk too – at around 7%.

However, sometimes babies (and adults) can have problems processing the assimilation of lactose. That usually comes about because the stomach has insufficient lactase to cope. That shortage may come about due to:

  • decreasing levels of lactase in the body – usually starting around 5 years of age but it can happen earlier;
  • genetic problems meaning no lactase is present at all – this is very rare;
  • infections and other causes leading to secondary lactose intolerance – this may be short-term;
  • lactose overload – this is slightly different and is discussed further below.

The symptoms of lactose intolerance in babies

Look out for:

  • lots of wind;
  • bloating and stomach pain;
  • diarrhoea

These symptoms though can always be due to another condition and only a medical professional will be able to diagnose accurately.

You might also see some related symptoms perhaps including:

  • a ‘grizzly’ baby for no obvious reason;
  • not gaining weight at the normal rate;
  • difficulty latchingon to the breast.

Don’t confuse lactose intolerance with a food allergy, though the symptoms may overlap slightly. The latter may result in other symptoms such as rashes, blemishes around the mouth, blood and mucus in faecal matter, swollen and itchy eyes etc.


A lot will depend upon the age of your baby, whether it is breast or bottle-fed and importantly, what your doctor diagnoses as the underlying cause.

For mild lactase shortages, many doctors will not recommend weaning. They’ll probably see the benefits of breast milk outweighing the typically modest consequences of mild lactose issues. If your baby is weaned or bottle-fed, they may recommend some feeding regime/product changes.

If your baby is diagnosed as having no lactase for genetic reasons, they will prescribe a course of specialised treatment.

If the problem is a secondary intolerance due to something like an infection, they may recommend treatment while maintaining the current approach to feeding.

Overloading your baby with lactose

This is a slightly different category and applies when the baby’s lactase is perfectly adequate but is simply unable to cope with the volume of lactose it is receiving.

This can happen to breastfeeding mothers where:

  • the baby switches breasts before the first is fully empty, leading to higher quantities of the more lactose-rich “first milk” being consumed;
  • babies who feed only for short periods even if more frequently.

This is usually solved easily by minor changes in feeding practice.

Older children and teenagers

Lactose intolerance can appear for the first time in slightly older toddlers and teenagers. There may be differences in symptoms and treatment regimes, which your doctor will advise on.

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