If your child has been diagnosed with a cow’s milk protein allergy (CMPA), or you think they might have CMPA, you might be feeling overwhelmed right now. Don’t worry, we’re here to help! In this blog post, we’ll give you all the information you need to know about CMPA.

What is CMPA?
Cow’s Milk Protein Allergy (CMPA) also commonly referred to as Cow’s Milk Allergy (CMA) is a reaction by the immune system to one or more proteins found in cow’s milk. The proteins that most commonly trigger an allergic reaction are beta-lactoglobulin and casein.
How common is CMPA?

Cow’s milk protein allergy is one of the most common food allergies in infants and young children. CMPA affects around 2 – 4.5% of infants under the age of one, and most children outgrow it by the time they reach school age. However, some children will continue to have CMPA into adulthood.
What causes CMPA?
The cause of CMPA is not fully understood, but it is thought to be due to a combination of genetic and environmental factors. Cow’s milk proteins are large and complex molecules that can be difficult for the digestive system to break down.
In some children, the digestive system is “leaky” and allows undigested proteins to pass into the bloodstream. The immune system then reacts to these proteins as if they were foreign invaders, leading to inflammation and the symptoms of CMPA.
CMPA Symptoms
When a child with CMPA ingests cow’s milk, they may experience symptoms such as vomiting, diarrhea, eczema, hives, wheezing, and/or difficulty breathing. In severe cases, anaphylaxis can occur. According to the Guidelines for the diagnosis and management of cow’s milk protein allergy in infants, these are the symptoms of CMPA, along with additional symptom facts about CMPA.
Please note: The symptoms can vary between breastfed and formula-fed infants (see below).
Mild to Moderate Symptoms in Breastfed Infants

- Frequent regurgitation
- Vomiting
- Diarrhea
- Constipation
- Rash
- Blood in stool
- Iron deficiency anemia
- Atopic dermatitis
- Persistent distress or colic
Severe Symptoms in Breastfed Infants
The severe symptoms are similar to the mild to moderate, but also include “Failure to Thrive”. According to Hopkins Medicine, Failure to Thrive is when the child’s weight or rate of weight gain is significantly below that of other children of similar age and sex.
- Diarrhea
- Regurgitation
- Vomiting
- Refusal to feed
- Moderate to large amounts of blood in stool
- Protein-losing enteropathy (protein leaked from GI tract)
- Severe atopic dermatitis
Mild to Moderate Symptoms in Formula-Fed Infants

Gastrointestinal
- Frequent regurgitation
- Vomiting
- Diarrhea
- Constipation
- Rash
- Blood in stool
- Iron deficiency anemia
Dermatological (skin)
- Atopic dermatitis
- Angio-oedema (swelling of lips or eyelids)
- Urticaria (hives)
Respiratory
- Runny nose
- Chronic cough
- Wheezing
General
Persistent distress or colic. Persistent is described as wailing or irritable 3 or more hours a day, at least 3 days a week, for 3 or more weeks.
Severe Symptoms in Formula-Fed Infants

The severe symptoms are similar to the mild to moderate, but also include “Failure to Thrive”. According to Hopkins Medicine, Failure to Thrive is when the child’s weight or rate of weight gain is significantly below that of other children of similar age and sex.
Gastrointestinal
- Chronic diarrhea
- Chronic regurgitation
- Chronic vomiting
- Refusal to feed
- Iron deficiency anemia
- Protein-losing enteropathy
- Enteropathy
- Severe ulcerative colitis
Dermatological (skin)
- Exudative (wet) dermatitis
- Severe atopic dermatitis
- Hypoalbuminaemia-anaemia (low albumin protein levels)
Respiratory
- Acute laryngoedema (larynx swelling)
- Bronchial obstruction
Systemic Reactions
- Anaphylactic shock
If your child has or you suspect has CMPA, and they have any symptoms, take them to a doctor. If the symptoms are severe or seem life-threatening in any way, get emergency medical help right away.
CMPA Rash Images
These images are of children who have been diagnosed with atopic dermatitis. Atopic dermatitis is the most common skin rash that physicians see with CMPA.






How is CMPA diagnosed?
If you suspect your child has CMPA, the first step is to schedule an appointment with your pediatrician. They will likely refer you to an allergist for further testing. There are two main types of tests used to diagnose CMPA: skin tests, and blood tests.
Skin Test
The skin prick test (SPT) involves placing a drop of cow’s milk protein extract on the skin and then making a small puncture in the skin (usually the back or forearm) so that the allergen can enter. If your child is allergic, they will typically develop a wheal (a raised, itchy bump) within 15 – 20 minutes.
Blood Test
Blood tests are also used to diagnose CMPA. These tests measure the levels of Immunoglobulin E or IgE antibodies in the bloodstream. These antibodies or immune system cells are responsible for allergic reactions. High levels of IgE may indicate an allergy.
CMPA Baby Formula
Once diagnosed with CMPA, your child’s Pediatrician may want to switch baby formulas. Read the CMPA Formula Guide next to gain a better understanding of the different types of formulas available.