9 Things You Need to Know About Cow Milk Protein Allergies

Updated: Feb 2

I have been super curious about the cow milk protein allergy since SO many of my clients have babies with milk (and soy and gluten) allergies or intolerance. Studies show that up to 1 in 7 (15%) infants have a cow milk protein allergy – although it may be more like 1 in 20 based on more controlled studies.

Cow Milk Protein Allergy Basics

There is no doubt that moms and dads who have babies with cow milk protein allergy (CMPA) are super educated on this topic. When you have a baby who has a rash, cough, wheezing (scary!), diarrhea, reflux, is inconsolable, or refuses to eat – you are desperate to figure out why! But for those who haven’t dealt with this first hand, let me catch you up on some of the basics.

Formula Fed Babies

Formula fed babies have a higher risk (2-5%) of having a cow milk protein allergy (CMPA) than breastfed babies (0.4-2.1%). This is because there is much less cow milk protein (CMP) in breastmilk than there is in a CMP-based-formula - like 100,000x less! Less protein... less chance to react to it.

Most Common Protein Allergy

CMPA is the most common milk protein allergy. Compare it to soy protein – where just 0.25% of babies have a soy protein allergy (that is 1 in 400)!

CMPA + Soy

Babies who have CMPA are at a higher risk (10-30%) of having a soy protein allergy as well – this is why so many breastfeeding mamas have to eliminate both dairy and soy from their diets. The reason for this...? An antibody specific to CMP has an affinity to a component of soy-based formulas (glycinin).


Babies who have a CMPA are also allergic to goat, buffalo, and ewe milk – but can tolerate camel’s milk (although not sure camel’s milk is readily available?).

Beef Allergy

Babies with CMPA have an increased risk (13-20%) of also having a beef allergy.

*Note – The percentages above are not the amount of increased risk, but rather the percentage of babies who have the cited condition.

Cow Milk Protein Allergy Diagnosis

Figuring out if your baby has a cow milk protein allergy (CMPA) can be a process.

Most babies with CMPA develop symptoms in at least two organ systems –

  • gastrointestinal (50–60%),

  • skin (50–60%) and

  • respiratory tract (20–30%).

Because GI and skin symptoms are very nonspecific (they can occur for a variety of reasons) – determining their cause can be confusing and frustrating. See below to see a list of symptoms that could indicate your baby has CMPA.

Elimination Diet

Currently, an elimination diet is the gold standard for diagnosing CMPA. This means switching your baby’s formula from a CMP-based-formula to an alternative formula, or for a breastfeeding mom, eliminating all foods with CMP from her diet. If symptoms improve after elimination, then reintroduce restricted items to see if symptoms return. Check out the algorithm (from The College of Family Physicians of Canada) for details.

Formula fed babies may actually improve faster (within 72 hours) than breastfed babies (after 7 days) once CMP is removed from their diet. In both breastfed and formula fed babies, however, colitis (inflammation and irritation of the colon which causes blood in stools) can take up to 3 weeks to heal. Some symptoms in formula fed babies may take up to a week to resolve.

NOTE - In order to provide adequate calcium to your baby during the elimination diet, be sure to take calcium supplements (1000 mg per day divided into several doses) each day.

Diagnostic Testing

Is there hope for an actual “test” to assist with diagnosis of CMPA? Studies show that using both a skin prick test and a blood test (of IgE antibodies) can diagnose one type of cow milk protein allergy (IgE mediated – 54%). These tests are often completed by Allergists for babies who have severe allergies – those who could potentially have anaphylaxis if reintroduced to the CMP. However, researchers are currently working on ways to diagnose the other type of CMPA (non-IgE mediated – 46%) with a patch test. Basically – stay tuned. For now, you must eliminate and watch for change.

Reflux and Colic vs CMPA

If your baby has reflux or colic, consider eliminating cow’s milk to see if symptoms improve. Small studies show that 20% of babies with reflux and 60-70% of babies with colic may have these symptoms due to cow milk protein allergy (CMPA).

Since there is currently no definitive test to diagnose CMPA, eliminating CMP from your diet (if breastfeeding) or your baby’s diet (if formula fed) is the best way to determine if your baby has a CMPA, and totally worth a try!


I do have some good news to share! If you are looking for a way to prevent cow milk protein allergy (CMPA), there may be an answer. A research study published in 2017 shows links between Vitamin D levels and CMPA.

Let me explain (this is going to get a little science-y, but hang tight)...

When our immune system works ideally, it attacks foreign things that can cause us harm (like bacteria, viruses, etc), and does not attack things that do not cause us harm (like cow milk protein). So, what keeps this in check? There are cells in our immune system called Regulatory T Cells (Treg cells). A deficit in Treg cells causes our immune system to over-react – and no one likes an over-reactor. Guess what helps create Treg cells – Vitamin D. So, to connect this for you – Vitamin D helps create cells that prevent our immune system from over-reacting to things that do not cause us harm, like certain food proteins.

This study showed that a Vitamin D deficiency (or even insufficiency) early in life is a risk factor for food allergies. Vitamin D levels were significantly lower in children with CMPA allergy (35 ng/mL) vs those without CMPA allergy (48 ng/mL – note 50 ng/mL is considered adequate). Makes sense now that you know how Vitamin D helps our immune system.

So, should you provide a Vitamin D supplement to your baby? All babies need Vitamin D. While it is possible to obtain adequate Vitamin D from sunlight, most babies don’t, and therefore need to get their Vitamin D from their diet. Breastmilk is low in Vitamin D, so breastfed babies should be supplemented with Vitamin D. Formula is fortified with Vitamin D, so no additional supplements are needed for formula fed babies.

Prediction of Tolerance

Although there are pretty standard recommendations for when to reintroduce cow milk to kiddos with cow milk protein allergies (reintroduce cow milk protein at age 1), more current research is showing us that there are factors that can help us predict which children will tolerate CMP sooner than others.

  • A Starting Point – A study from 2004 showed that children ages 2, 3, and 4 with non-IgE-mediated allergies (64%, 92%, 96%) tolerate CMP sooner than children with IgE-mediated allergies (31%, 53%, 63%).

  • Individualized Predictions – A study from 2017 showed that Vitamin D is a good predictor of whether babies will tolerate CMP at age 1. Babies with Vitamin D levels lower than 40 ng/mL predicted that they would still be allergic at age 1.

Take Away – Most pediatricians still recommend trialing CMP at age 1. However based on the 2004 study, you may consider delaying introduction past 12 months if your kiddo has IgE-mediated allergy (or seeing an allergist for recommendations). On the contrary, you may feel more confident reintroducing CMP at 12 months if your munchkin had a Vitamin D level above 40 ng/mL at diagnosis.

Genetic Risk Factors

A shocking number of mamas have shared that multiple children in their family have had an allergy to cow milk protein. Turns out, both genes and your kiddos own health history play a role in your little one’s risk for having a cow milk protein allergy (CMPA).

Babies who have moderate to severe atopic dermatitis (or eczema) have an increased risk of having CMPA – and other food allergies. The risk is actually pretty significant – check it out.

  • The risk of being sensitized to cow milk protein was four times higher in babies with eczema.

  • The risk of being sensitized to egg was an astounding eight times higher in babies with eczema.

This is where genetics comes in – Babies have an increased risk of having allergies, eczema, or asthma if their parents (20-40%) or siblings (25-35%) have allergies, eczema, or asthma.

So if you, your parents or siblings have allergies, eczema, or asthma, you are much more likely to have a CMPA.

Risk For GI Issues Later In Life

I wish I had better news. But unfortunately, the truth is, that cow’s milk protein allergies (CMPA) seemingly puts you at increased risk of having GI issues later in life.

There are a handful of studies demonstrating this unfortunate consequence to the inflammation, changes to the absorption, motility, and bacteria of the intestines, and sensitivity of the abdominal organs, that cow milk protein allergy causes. Check out the details below.

  • A study from 2011 shows kiddos who had CMPA (44%) have an increased incidence of abdominal pain, constipation, and diarrhea compared to those who did not have CMPA (20%).

  • A study from 2010 shows the odds of developing constipation @ 24 months was 1.57 higher in individuals who had CMPA during the first year of life.

  • A study from 2014 shows that 9% of children with food sensitivities (not specific to CMPA) at age 4 and 8 report recurrent abdominal pain.

  • A study from 2017 shows that the odds of developing Irritable Bowel Syndrome (IBS) was 1.54 times higher in children with food allergies – and that these children develop IBS 2.35 years sooner than most individuals with IBS.

  • A study from 2018 shows that the odds of developing GI disorders (most commonly IBS) was 4.39 times higher in children who had allergic proctocolitis (bloody stools d/t CMPA).

This is nothing to lose sleep over. It does not mean that if your kiddo has CMPA he or she is destined have GI issues later in life. It just means that there is an increased risk, and therefore you shouldn’t ignore symptoms if they do arise.

Formula Choice

Formula choice for babies with cow milk protein allergies may influence how soon your baby is able to tolerate dairy products. Check it out.

A study from 2013 showed that use of extensively Hydrolyzed Formula (eHF) supplemented with probiotics (Lactobacillus rhamnosus) accelerated tolerance of cow milk protein. The rate of babies who tolerated CMP at 12 months was significantly higher in babies fed eHF (43.6%) or EHCF + lactobascillus probiotic (78.9%) compared with the other groups: hydrolyzed rice formula (32.6%), soy formula (23.6%), and amino acid based formula (18.2%). Check out more info on The Truth Of Probiotics and Children here.

A study in 2018 showed that babies given soy-based formula lack the healthy bacteria and exposure to protein chains that help break down cow milk protein in the future.

This same study also showed that babies given rice hydrolyzed formula had less of the healthy gut bacteria that utilizes lactose. This could potentially affect tolerance of dairy products when the CMPA is actually resolved – these babies may not be able to tolerate dairy due to lactose intolerance.

At The Dentist

A little side note for those kiddos who have not outgrown their CMPA by the time they go to the dentist and receive fluoride treatments.

Casein (the protein in cow’s milk,) is found mainly in milk, cheese and yogurt. Use of - fancy word alert - Casein Phosphopeptide Amorphous Calcium Phosphate (CPP-ACP) instead of fluoride applications has been increasingly common at some dental offices. Also, CPP-ACP was added to sugarless gum, and some other dental products.

Bottom line - don't be afraid to notify your dentist of your kiddos CMPA and ask about the products they are using.

Knowledge Is Power

I think we can all agree that the cow milk protein allergy really stinks. However, knowledge is power! Be sure to share your new found knowledge with all your mommy and daddy friends who are dealing with a diagnosis (or a protentional diagnosis) of cow milk protein.

Katie Ramirez, RN, BSN, CLC

Born Happy, Owner and Coach

Katie Ramirez is a Registered Nurse, Certified Lactation Counselor, and Coach for parents of babies and toddlers. She has spent more than a decade serving patients at major university hospitals such as Vanderbilt University and Penn State University Medical Centers. Katie now spends her time supporting and empowering parents of babies and toddlers as owner and coach for Born Happy.

Katie is the proud mother of two beautiful children, Roberto (age 5), and Veronica (age 3). She has a passion for health, wellness, and happy children, and believes that, with the necessary knowledge and support, all parents can live happy.

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