Cow's milk protein allergy and lactose intolerance: What’s the difference?

It is not uncommon to be confused about the difference between a real cow’s milk protein allergy and an intolerance to lactose, but they are actually quite different. They have different symptoms, generally affect different age groups and require different dietary changes.  Find out what the differences are, and when it may be necessary to remove milk protein and dairy completely from your little one’s diet.

What is a food allergy? And what is a cow’s milk protein allergy?

A food allergy happens when the body's immune system, which helps to fight infections, sees the food as an intruder and responds by releasing chemicals like histamine into the body. This is what is known as an allergic reaction and generally results in symptoms like skin irritation, swelling of the lips and sometimes gastrointestinal upset symptoms.  

If your baby has a cow's milk protein allergy, it means your baby's immune system has reacted to the proteins in milk. While cow’s milk protein is one of the most common causes of food allergy in infants (affecting about one in every 50 children), most eventually outgrow their allergy before adulthood. 

Symptoms of any food allergy, including cow’s milk protein allergy, include: swelling of the lips, face or eyes, eczema, breathing problems, diarrhoea, reflux, vomiting or poor weight gain. 

Importantly, dietary management of cow’s milk protein allergy requires complete removal of milk proteins and dairy products from the diet. It is therefore essential to get a correct diagnosis from a healthcare professional and advice from a registered dietitian before making dietary changes.  

Learn more about Cow’s Milk Protein Allergy and how it is diagnosed and treated.

What is a food intolerance? How does a milk allergy differ from a lactose intolerance?

A food intolerance means the body cannot properly digest a certain food, or that particular food might aggravate the digestive system. 

In the case of lactose intolerance, this describes the symptoms related to the incomplete breakdown of lactose, which is the natural sugar found in breast milk and cow’s milk. Lactose intolerance is relatively uncommon in babies. By comparison, cow’s milk protein allergies tend to appear within the first year of life. Some babies can temporarily suffer from lactose intolerance after a gastrointestinal infection, but this will thankfully eventually go away. Generally, symptoms of lactose intolerance are more likely to develop during the childhood to adolescence period becoming more noticeable in adulthood. However, most adults with lactose intolerance can comfortably consume some yoghurt, cheese or a glass of milk when spread out over the day – especially when eaten with a meal. 

It is again important to get a correct diagnosis from a health professional before making dietary changes if you suspect a lactose intolerance. 

Learn more about lactose intolerance and how common it is in children.