Cow’s Milk Protein Allergy and Lactose Intolerance Explained

milk allergy and lactose intolerance explained


There can be a lot of confusion surrounding food allergies and intolerance. Many people know a little about it, but when it comes down to explaining it are not 100% sure what each mean and what the differences are. Quite often when I say my children cannot have milk, people will say ‘oh are they lactose intolerant?’, and then I get a blank stare when I reply that they are allergic to the protein in milk. Of course many readers of this site will already know all about it. I believe that education about food allergies and intolerance can go a long way to clearing up the myths and increasing allergy awareness in a positive way.

So here’s the science bit:

Allergy – an allergy is an immune response to a substance e.g. dust, pollen, foods. Even a tiny amount of the substance can trigger this response. The body identifies the allergen as harmful and produces antibodies to protect against it.  The response is usually an inflammation of the airways, skin, intestines or sinuses. The response can vary from person to person, in some it can cause minor irritation and in others it can be extremely serious – anaphalactic shock which is life threatening. 

Intolerance – an intolerance is an inability to take a particular food without suffering adverse effects. It is not an immune response and not life threatening.

The main differences between a food allergy and a food intolerance are:

  • An allergy usually develops within minutes of eating the food, and an intolerance can develop many hours later.
  • An allergy can be triggered by a tiny morsel of food (or an airborne particle in the case of nut allergies) whereas usually an intolerance would need a larger amount of that food for symptoms to develop.
  • An allergy can be life threatening, whereas an intolerance cannot.


Cow’s Milk Protein Allergy CMPA

Cow’s milk protein allergy can be divided into two types:

The first has always been called Cow’s milk protein allergy and is immediate and is now called IgE-mediated because the antibody immunoglobulin E is present and causes the symptoms seen with allergies.

The second type has traditionally been named cow’s milk protein intolerance and can now also be called Cow’s milk protein allergy non IgE mediated as it does not have the antibody present and symptoms are not immediate.

Cow’s Milk Protein Allergy CMPA (Cow’s Milk Protein Allergy IgE mediated)

Cow’s milk protein allergy is an immune response to the protein in milk, as with other allergies it can range in severity from mild to severe and it can be life threatening.  Symptoms can be a rash, hives, swollen lips, cramps, diarrhoea, vomitting and difficulty breathing. It occurs within 2 hours of consuming the milk. Milk allergy can be extremely serious and within minutes can cause anaphylaxis.

Cow’s Milk Protein Allergy non IgE mediated (previously known as Cow’s Milk Protein Intolerance CMPI)

The symptoms are eczema, stomach cramps, diarrhoea and vomitting. They can occur from a few hours after ingesting the milk to a few days after. This is more common in children than in adults and many children will grow out of it before the age of 5 or 6.


Lactose Intolerance

Lactose Intolerance is the other main issue people can have with milk products. Lactose is the sugar found in milk, some people cannot digest this sugar due to lack of the enzyme lactase in their system. The symptoms can be bloating, flatulence and diahorrea. It is not life threatening.



Information taken from

Irish Food Allergy Network – Milk

HSE – Diagnosing Food Allergy

HSE – Lactose Intolerance

NHS – Dairy Foods



Add a Comment

Your email address will not be published. Required fields are marked *