Lactose Intolerance in Babies

This is an inability to digest the type of sugar found in milk, called lactose, but it is not an allergy and is treated differently to cow’s milk protein allergy. The NHS Choices website has more about treating lactose intolerance.

What is lactose intolerance in babies?

Lactose is the main sugar found in all forms of milk, whether it's breast milk, formula milk or animal milk. Lactose is an important source of carbohydrates for babies, but in order for the body to use lactose it has to be broken down by an enzyme in the body called lactase.

If your body does not produce lactase, or doesn't produce enough of it, then you can't use the lactose in milk to provide energy – and the undigested lactose can produce uncomfortable symptoms. This is called lactose intolerance.

Lactose intolerance is different from an allergy, where the body mistakes a protein within a specific food as harmful and has an immune response to it. It's not possible to have an allergy to lactose, because lactose isn't a protein.

What are the symptoms of lactose intolerance in babies?

The symptoms of lactose intolerance can vary, especially in babies, but you might notice the following:

  • Diarrhoea
  • Being unsettled
  • Frequent crying
  • Loose, watery stools (may be green/yellow in colour)
  • Trapped wind
  • Flatulence
  • Noisy bowel sounds
  • Vomiting

These symptoms might occur anywhere from a few minutes to a few hours of having milk or milk products. Since the symptoms are so general, and can also be caused by other things, it can be quite hard to spot lactose intolerance in a young baby.

Types of Lactose Intolerance

There are three different types of lactose intolerance:

1. Hereditary lactose intolerance: Baby is born without any of the lactase enzyme. Symptoms tend to occur after the first milk feeds, and can be quite severe.

2. Primary lactose intolerance: Baby is born with the lactase enzyme, but the amount gets smaller over time and symptoms increase. The baby might be able to have small amounts of milk, but over time lactose free baby formula alternatives may need to be used. 

3. Secondary lactose intolerance: A temporary condition where illness affects how well the body can make the lactase enzyme. Symptoms usually go away after 3-4 weeks.

How is lactose intolerance diagnosed?

If you suspect your baby may have lactose intolerance, it's important to see your GP as soon as possible, to rule out anything else might be causing the symptoms. Your GP may take a medical history, look at how well your baby has been growing and make a note of any symptoms you've noticed. They might also ask you to try giving your little one a lactose-free milk for babies and avoiding weaning foods that contain lactose for a trial period to see if this solves the problem. If it does, your GP may ask you to continue with this diet to stop the symptoms from coming back.

How is it treated and what lactose free formulas are available?

If your baby is diagnosed with lactose intolerance, you'll need to avoid lactose, both in milk and in foods. For very young babies, this will involve switching to a lactose-free formula milk for babies and weaning diet, and they may need additional calcium, magnesium and zinc to replace what they aren’t getting from milk.

For older babies, you may need to swap from a milk-free formula to a lactose-free milk (found in most supermarkets), and check ingredients labels on other foods carefully to make sure they don't contain lactose. Look for the following words on ingredient lists: milk, whey, curds, milk by-products, dry milk solids, non-fat dry milk powder.

With primary lactose intolerance, toddlers can sometimes tolerate small amounts of foods with lactose, such as cheese and yoghurt. In this case, your GP or dietitian can advise you.

This can all sound a bit daunting, but there's a silver lining: removing the lactose usually resolves the symptoms, which leads to a healthier, happier baby. Also, many supermarkets now have quite a good range of lactose-free products.

All HiPP packaging lists cows’ milk as an ingredient and also highlights it in a yellow ‘CONTAINS’ box to make things a bit easier.