Cow’s milk protein allergy (CMPA) [What is CMPA] is the commonest food allergy in babies and young children. It usually starts at an early age, during the first few months of an infant's life. It is not always easy to make a quick diagnosis since the symptoms are very varied and not specific to CMPA. [Diagnosing and treating CMPA in babies].

How can you, as parents, detect this dietary problem? What are the warning signs? Focus on the symptoms of CMPA.

There are two types of cow’s milk protein allergy: “IgE-mediated CMPA” and “non-IgE-mediated CMPA”. While the first type may persist as the child grows older (about 20% of cases), the second type will always improve relatively quickly.

Does your child have IgE-mediated CMPA?

IgE-mediated CMPA is the least common cow's milk protein allergy in children. The allergic reaction is due to the production of “IgE” antibodies, which target the cow's milk proteins (CMP) ingested by the child. Below are a few keys to help you identify it. 

The symptoms of IgE-mediated CMPA

The symptoms of this allergy vary from one individual to another. They usually take the form of acute signs, which may sometimes be serious in babies. Your baby may have CMPA if they present one or more of the following reactions: 

• Skin reaction: itching, skin redness, urticaria (hives), angioedema (swelling),
• Digestive reaction: angioedema of the mouth, nausea, projectile vomiting, severe abdominal pain, acute diarrhoea,
• Respiratory reaction: rhinitis, bronchospasm (contraction of the airways), asthma, conjunctivitis, 
• Other: malaise, loss of consciousness, drop in blood pressure, anaphylactic shock.

The onset of symptoms of IgE-mediated CMPA

The onset of symptoms is usually rapid in babies: a few minutes to 2 hours after the intake of cow's milk protein. 

Diagnosing IgE-mediated CMPA

If CMPA is suspected, the doctor will carry out the following tests to confirm the diagnosis: 

• A “skin-prick” test

A drop of the baby's usual milk is placed on their arm. A small skin-prick is then made through the drop. In IgE-mediated CMPA, a wheal (local swelling reaction) quickly develops.  

• A “CMP RAST” blood test

In this test, the IgE antibodies to milk normally found in demonstrated IgE-mediated CMPA are measured in a small amount of blood taken from the child. It the test detects the presence of these antibodies, the child is said to be “sensitive to CMP”. However, it should be noted that this does not necessarily mean the child is allergic. 

• "An “oral challenge test (OCT)”

After symptoms have disappeared following a cow's milk protein avoidance diet, the child is given a little milk and watched to see whether or not the symptoms of CMPA reappear. This test is rarely performed because it can be dangerous for young babies. But don’t worry: when it is performed, it is supervised and carried out by professionals in a hospital setting.

For IgE-mediated CMPA to be diagnosed, taking cow's milk protein must cause symptoms to appear within a short period of time. If laboratory tests are positive but there are no symptoms, then the child is said to be sensitive to CMP rather than allergic. 

If your child has symptoms that may indicate CMPA, you should contact a healthcare professional without delay to seek a diagnosis. Only a professional will be able to advise on how to manage babies with allergic reactions. 

Does your child have non-IgE-mediated CMPA?

The majority of children with CMPA have the non-IgE-mediated form. In this type of allergic reaction, no IgE antibodies are produced. It is the child's own immune system cells that are involved, working together to try to eliminate the cow's milk proteins. A number of elements may lead you, as a parent, to suspect this possibility, but it is more difficult to diagnose than IgE-mediated CMPA.

The symptoms of non-IgE-mediated CMPA

The symptoms of this form of allergy are generally chronic. If your child has any of the following reactions, it is possible that they may have developed an allergy of this type: 

• Skin reaction: itching, skin redness, eczema,

• Digestive reaction: gastroesophageal reflux (GER), colic, feeding difficulties, abdominal pain, chronic diarrhoea, presence of blood and mucus in their stools, constipation, anitis (inflammation of the anal area), anal fissures,

• Respiratory reaction: chronic cough,

• Other: anaemia (lack of red blood cells), iron deficiency (lack of iron), poor weight gain, disturbed sleep.

The development of symptoms of non-IgE-mediated CMPA

Symptoms develop from a few hours to a few days after taking milk or a food containing milk (or its introduction, during the complementary feeding - or weaning - period). Therefore the link between symptoms and milk consumption is sometimes difficult to establish.

Diagnosing IgE-mediated CMPA 

Different tests can be used to detect this type of CMPA: 

• Negative skin-prick and CMP RAST tests

• The use of a “patch test”: a small aluminium cup filled with milk is placed on the child’s skin. It is kept in place for 48 hours and then compared with a control patch test, to detect allergy or otherwise. This method is rarely used, and its reliability is questionable.

It can sometimes be tricky knowing whether a child has non-IgE-mediated CMPA since there is no lab test to detect it. In addition, the late onset of symptoms makes its diagnosis difficult. To eliminate any doubt, it is recommended to carry out a test by totally avoiding CMP for a period of 4 weeks and watching to see if the signs disappear. If symptoms come back again after reintroducing CMP, the child has non-IgE mediated CMPA.

Although some of the symptoms of CMPA may seem particularly alarming, rest assured that the allergy does not last forever in babies. In the meantime, your baby’s doctor can offer specific treatment based on their profile and the diagnosis made (adapted diet for the mother and breastfed baby [CMPA and breastfeeding], special infant formula for bottle-fed babies, avoidance of foods containing milk proteins, particularly during the complementary feeding (weaning) phase [Complementary feeding and CMPA in children]. Once the infant has recovered, you can start reintroducing dairy products into their diet. [Reintroducing dairy products after CMPA]

Annexes :

Fiocchi A, Schunemann H. WAO Special Committee on Food Allergy. Diagnosis and Rationale for Action against Cow’s Milk Allergy. The DRACMA guideline. WAO Journal 2010; S1 (April), 1-105

C.Dupont, J-P Chouraqui, D de Boissieu, et al. Comité de nutrition SFP. Prise en charge diététique de l’allergie aux protéines du lait de vache. Arch Pediatr 2011;18:79-94

Vandenplas Y, Marchand J, Meyns L. Symptoms, Diagnosis, and Treatment of Cow’s Milk Allergy. Curr Pediatr Rev. 2015;11(4):293-7.


Dupont, C. ; Chouraqui, J.P. ; Linglart A. et al. Committee on Nutrition of the French Society of Pediatrics. Nutritional management of cow’s milk allergy in chidren: an update. Arch Pediatr, 2018, 25, 236–43.

Bocquet A, Dupont C, Chouraqui JP, et al. Committee on Nutrition of the French Society of Pediatrics (CNSFP). Efficacy and safety of hydrolyzed rice-protein formulas for the treatment of cow’s milk protein allergy. Arch Pediatr. 2019 May;26(4):238-246.

Mpedia, APLV : l’Allergie aux Protéines du Lait de Vache, https://www.mpedia.fr/art-aplv-allergie-proteines-lait-vache/