Cows Milk Protein Allergy

Cow’s Milk Protein Allergy CMPA has increased significantly over the last decade, particularly in first world countries. It is primarily a problem of infants and toddlers. This article provides some background and discussion on CMPA. Only 10% of infants will be allergic to milk alone. Most will also be allergic to egg and/or peanuts.


What is it ?

When coming into contact with cow’s milk the most common abnormal reaction is a dermatitis that develops within the hour. This can be generalised or localised to the face and mouth area. Ocassionally the reaction is more severe, with the development of welts and hives and even problems breathing. Some infants can develop a serious enough reaction to require urgent medical help, called anaphylaxis, but luckily this is rare. There are some specific reactions to cow’s milk that is restricted to infants.

Food protein induced enterocolitis syndrome – a disorder of young infants due to cow or soy milk. Present with delayed onset (1 -3 hours after allergen ingestion) of protracted vomiting and sometimes floppiness and pallor that can be misdiagnosed as infection.

Food protein induced enteropathy – presents with milder form of diarrhoea, vomiting and poor weight gain.

Cows milk protein can sometimes be a factor in those infants who have eczema. Dairy products will sometimes make eczema significantly worse, but on the other hand totally avoiding dairy does not usually prevent a child from developing eczema.

This food allergy is usually cofined to infants and young children. 85% of those who have CMPA will grow out of this allergy as they get older.

Other dairy problems

Many mothers and child care workers believe that other symptoms such as vomiting, reflux, infant irritability, colic are due to cow’s milk allergy. Although in some instance this is due to dairy it is not a true allergy, but is more an intolerance. See the article above on food allergy in general for more discussion.

How does it occur ?

For some reasons that are not entirely clear the presence of the dairy protein triggers a reaction in the immune system that makes the body think it is under attack. The offending protein links up to an antibody called IgE. The IgE reacts with cells under the skin and in the body which release lots of chemicals that cause the allergy symptoms such as dermatitis. This is called an IgE reaction. Severe IgE reactions cause anaphylaxis.

When Does it Occur ?

Some infants are exposed to the diary protein when it crosses the placenta. Sometimes it is during breastfeeding. This is called sensitisation.

Diagnosing using Skin Prick testing

One of the most accurate ways of detecting CMPA is through skin prick testing. The forearm has a drop of cow’s milk protein extract impregnated just under the skin and if there is the development of a small insect bite like mark then this is said to suggest allergy to Cow’s milk protein. If there is no reaction at all then it can be assumed there is no risk of IgE reactions. This is usually done along with other food proteins such as egg, soy, peanut.

These tests are generally safe and accurate and if done properly using appropriate distraction techniques are well tolerated by infants toddlers, and children. For those with positive skin prick tests they should be repeated every year to determine if the allergy has disappeared as mentioned.


  • Infants – During the first few months if breast fed then the Mother will need to avoid milk proteins. The strictness will depend a little on how severe the reaction is. As solids are introduced foods will need to be checked to ensure diary products are not included.
  • Toddlers – if history and or skin prick testing show ongoing problems with dairy then totally avoiding diary continues.

As mentioned most toddlers will grow out of CMPA. If a skin prick test becomes negative then it is safe to perform an oral challenge especially if previous reactions were simply skin reactions. For those rare infants who have serious cow’s milk protein reactions (anaphylaxis) then oral food challenges should only be done under strict medical supervision.

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