Signs Your Breastfed Baby Has a Cow's Milk Allergy

Breastfeeding infants can develop allergies to foods they’re exposed to through their mother’s breastmilk. One example is cow’s milk. When unaddressed, a cow’s milk protein allergy can seriously affect a baby’s health and development.

Food allergies in infants can be tricky to diagnose, but it’s important to identify them as soon as possible, says University Hospitals family medicine nurse practitioner and internationally board-certified lactation consultant Jennifer McKinnon, DNP, APRN, IBCLC. Once diagnosed, the breastfeeding mom can make adjustments to her diet so that she can continue to breastfeed and her baby can thrive.

Cow’s Milk Allergy vs. Lactose Intolerance

A cow’s milk allergy is different from lactose intolerance, though they may share similar symptoms. A cow’s milk allergy triggers an immune response to the proteins found in milk (casein and whey). Lactose intolerance is a non-immune sensitivity to the lactose, or sugar, found in milk.

Lactose intolerance causes symptoms like fussiness, gas, blood or mucus in stool, nausea, spit up and diarrhea. While exposure to lactose may cause your baby discomfort, it will rarely cause any long-term problems.

A cow’s milk allergy can cause serious problems in a baby’s development, such as poor weight gain, weight loss and failure to thrive, explains Dr. McKinnon. Common symptoms may include:

• Hives
• Swelling under the skin, especially around the eyes or mouth
• Swelling of the tongue or throat
• Wheezing or respiratory distress
• Low blood pressure (hypotension)
• Vomiting

Cow’s milk allergies affect less than 0.5 percent of breastfeeding infants, compared to 2–7.5 percent of formula-fed infants. Infants are at greater risk for a cow’s milk allergy if one or both parents has a food allergy, hay fever, asthma or eczema. Infants with asthma and/or eczema also have a higher likelihood of developing a food allergy.

Diagnosing a Milk Allergy

If your baby is experiencing symptoms, it’s important to talk with your child’s healthcare provider before eliminating dairy or other potential allergens from your diet.

“What I’ve commonly seen is the risk of misdiagnosing and prematurely abandoning breastfeeding or severely limiting mom’s diet, thinking the baby is allergic to certain things,” says Dr. McKinnon.

If your child’s healthcare provider suspects a cow’s milk allergy, they may first recommend trying an elimination diet or specialty formula to help determine if an allergy is present. In some cases, they may refer you to a pediatric allergist for further testing, which could include a skin prick test and/or an antibody blood test known as an immunoglobulin E (IgE) test.

Eliminating Dairy From Your Diet

If a milk allergy confirmed, breastfeeding moms will need to eliminate all cow’s milk and cow’s milk products from their diet. In addition to avoiding typical dairy products like milk, cheese, butter and yogurt, she will need to read food labels carefully and avoid products with ingredients derived from cow’s milk.

Look for labels that say “may contain milk” or ingredients such as:

• Casein
• Caseinate
• Galactose
• Ghee
• Lactose
• Lactulose
• Nougat
• Quark
• Recaldent
• Rennet
• Simplesse
• Whey

It can take up to two weeks for an allergen to be eliminated from breastmilk, and it may take two weeks or more to fully resolve all symptoms.

What to Eat Instead

The four main nutrients in cow’s milk are calcium, potassium, vitamin D and protein, so breastfeeding moms who eliminate dairy should focus on foods high in these. Some good choices include chia seeds, soy milk, nuts, dried figs, tofu, lean meat, fish, beans, fortified orange juice and sunflower seeds.

Dr. McKinnon notes that vitamin D is the one vitamin that can’t pass to a baby through breastmilk, so all breastfed infants should be supplemented with 400 IU of vitamin D a day if at least half of their feedings are breastmilk.

Most infants eventually outgrow their cow’s milk allergy, so you may be able to reintroduce dairy as they get older. Dr. McKinnon generally recommends that moms reintroduce some dairy into their own diet first and see how the baby does. This can be followed by cooking dairy into other foods before giving baby straight dairy products.

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