What exactly is a Cow’s Milk Protein Intolerance (CMPI)?

What exactly is a Cow’s Milk Protein Intolerance (CMPI)?

Cow’s milk protein intolerance (CMPI) is defined as an abnormal reaction by the body’s immune system to one or both of the proteins, Casein & Whey found in Cow’s Milk.  It is not to be confused with Lactose Intolerance which is the inability to digest the carbohydrate (milk sugar) found in all mammals’ milk, including human breast milk. The immune system normally protects our bodies from harm caused by bacteria or viruses. In CMPI the immune system reacts unusually to the protein found in cow’s milk. This reaction can cause injury in the stomach and intestines.

It’s common to develop a CMPI by having a parent or sibling with an allergic disease (like asthma, eczema, and seasonal allergies). Breastfeeding seems to protect infants from developing CMPI.

Different types of Cow’s Milk Protein Intolerance

Cow’s milk protein intolerance can be divided into ‘immediate reaction’ and delayed reaction’ types. The two types have different symptoms associated with each.

Immunoglobulin E, is the antibody responsible for causing the allergy symptoms in humans, I.e. hives, rashes, wheezing and runny nose. In Immediate cow’s milk protein allergy, symptoms usually start within 2 hours of drinking cow’s milk. In delayed CMPI, symptoms happen later, from 48 hours to 1 week after drinking cow’s milk.

What are the signs and symptoms of Cow’s Milk Protein Intolerance?

Signs and symptoms of cow’s milk protein intolerance are very diverse. The symptoms will usually develop within the first week of starting cow’s milk in their diet. Most infants can show signs that involve the skin or the digestive system, including vomiting, abdominal pain, blood in the stools, and diarrhoea. Skin manifestations include hives and eczema. Babies can also present with wheezing, irritability, facial swelling, and poor growth due to poor absorption of nutrients.

Red flags include increased tiredness or lethargy, fevers, severe vomiting or diarrhoea, not tolerating any feedings, weight loss, and blood in the stools.

How is Cow’s Milk Protein Intolerance diagnosed?

A health practitioner will want to listen to the history symptoms and perform a physical examination to help determine diagnosing CMPI. Describing what your child is experiencing to the doctor is very important in making the diagnosis of this disease. The timing of the symptoms in relation to starting feeds with cow’s milk protein is also key in diagnosis. Whether there is a family history of allergies, asthma, or eczema can be helpful for diagnosis.

CMPI also is diagnosed after seeing how your child responds to the elimination of cow’s milk from the diet. You may be asked to keep a diary or try a prescribed elimination diet.

Test in children to diagnose Cow’s Milk Protein Intolerance?

Checking for blood in the stool of infants suspected of having CMPI can be helpful in diagnosing this disorder. Blood tests and other invasive studies are not always helpful in diagnosing cow’s milk protein intolerance. Your doctor may recommend tests to rule out any other problems.


The treatment of CMPI includes eliminating cow’s milk protein from the infant’s diet. Elimination diets are usually started with extensively broken down formulas. These formulas are made up of broken down proteins and are able to be digested without an immune reaction. These formulas will work in 90% of patients with CMPI. In some patients, it is necessary to use amino-acid based formulas, which are formulas containing the individual building blocks of proteins.

In breastfed infants with CMPI, the mother must exclude all dairy and soy products from her diet if she continues to breastfeed. This may be difficult, and is helped by having a dietitian discuss hidden sources of dairy and soy with the mother prior to starting the elimination diet.

Giving infants goat’s milk or sheep’s milk will not improve CMPI. Soy milk also is not recommended. Many infants will have similar allergic reactions to the proteins in these milks or soy-based formula and they do not carry enough nutritional value to be exclusively used in an infants diet.

What if my child has Cow’s Milk Protein Intolerance?

Fortunately, cow’s milk protein allergy resolves in 90% of children by the age of 6 years. 50% of infants will have tolerance at age 1 year, and more than 75% will have resolution by 3 years of age.

Most infants that are started on cow’s milk-free formulas or breastfed by a mother on a cow’s milk-free diet will need to remain on the diet for about 6-12 months. At that point, the child can be challenged with cow’s milk, and if they have no reactions, milk can be put back into the child’s diet.

Previous article Guide to healthy breastfeeding diet for reflux babies