We investigate the difference between lactose intolerance and a milk allergy

If your baby seems to continuously struggle through a feed and cries and moans straight afterwards, you might suspect lactose intolerance, or a milk allergy. But how do you know for sure? By Tammy Jacks


Because digestive problems like gassiness, cramps and bloating are fairly common in babies, it can be quite tricky, as a parent, to identify whether the problem is serious or not.

Registered dietitian and spokesperson for the Association for Dietetics in South Africa, Nathalie Mat, answers some common questions to help determine whether your little one is lactose intolerant, or if it’s a milk allergy.

ALSO SEE: Understanding the difference between a food allergy and a food intolerance

What is the main difference between a milk allergy and lactose intolerance?

Lactose intolerance is the inability of the digestive system to break down lactose, the main carbohydrate in milk. Between 60 and 70% of the world’s adult population lose the ability to break down lactose at some point. However, most babies are born with enough of the enzyme lactase in the  and true lactose intolerance only develops from the age of five. Temporary lactose intolerance can occur if a little one has an underlying condition such as gastroenteritis, but this resolves as the condition does.

On the other hand, cow’s milk protein allergy is when a little one’s immune system reacts to a component in the milk. The initial symptoms may look similar, but the underlying causes are very different.

What are the main symptoms of lactose intolerance – and of milk allergy? How do they differ?

Lactose intolerance

If you suspect your child is lactose intolerant, a main symptom is diarrhoea, which usually occurs within an hour after a feed. The diarrhoea may be green instead of yellow (if your baby is exclusively breast or bottle feed). Other symptoms of lactose intolerance include:

  • Stomach bloating, pain and cramping
  • Frequent colds
  • Nausea (although it’s hard to identify this symptom in little ones)

Milk allergy

When the immune system is producing a particular group of antibodies against the milk (IgE antibodies) the symptoms that occur are generally quite fast after ingestion of the milk and can be quite severe. These include:

  • Rash or itchy skin
  • Wheezing
  • Pain and tummy cramps
  • Diarrhoea
  • Low blood pressure
  • Shock and altered levels of consciousness, which is extremely alarming for parents.

The symptoms of a non-IgE mediated allergy (which is the other type of milk allergy) could take longer to develop and can be very similar. Some other common conditions include:

  • Constipation
  • Reflux
  • Colic
  • Vomiting
  • Severe flatulence
  • Severe eczema

How soon do these symptoms start?

Symptoms can flair up as soon as your baby is exposed to milk, whether she’s breastfed or formula fed. But they can also develop over time which makes it difficult to diagnose.

What to do if you suspect lactose intolerance

If you think your little one might be lactose intolerant, the first step is to speak to your clinic nurse or doctor. It’s important to remember that if your child has a tummy bug or some sort of gastroenteritis, the lactose intolerance will be temporary.

However, if doctors confirm that your baby has a disease of the small intestine such as celiac disease, she may do well on a low lactose formula until the inflammation resolves.

ALSO SEE: 5 baby tummy troubles and how to treat them

What to do if you suspect a milk allergy

In terms of prevention, the best strategy is to breastfeed exclusively. However, this isn’t always possible. If you have a family history of allergies and you can’t breastfeed, you can choose a hypoallergenic formula as your starting point.

Hypoallergenic formulas are partially broken down to reduce the likelihood that your little one will develop an allergy to the protein, but these become redundant once your little one has already been exposed to standard formula. This means that your child’s milk allergy will be confirmed by exclusion of the milk, but your doctor won’t want to do this unnecessarily as dairy is a very nutritious source of food for babies and shouldn’t be excluded unless under the supervision of a health professional.

ALSO SEE: 5 nutritional benefits of milk for kids

TOP TIP: Your breastfeeding diet and allergies

If your baby fusses a lot during or after a feed, many people might suggest that you avoid dairy, certain vegetables or spices. However, Nathalie says you should think twice about making unnecessary exclusions to your diet. If there’s a history of allergies in your family, choose a paediatrician with a special interest in allergies so that you can get up-to-date information on how to diagnose the problem. “The field of allergy management has changed considerably in the last 10 years, so you might see a lot of conflicting information on allergy management in books and online depending on how up-to-date the source is,” warns Nathalie.

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