How Do I Know If My Baby Has a Cow's Milk Allergy?

Learn about milk allergy symptoms and hypoallergenic formulas

Mother With Curly Brown Hair Feeding Her Baby With Bottle

Cow’s milk allergy, also known as cow’s milk protein allergy (CMPA), is a common childhood food allergy, and infants who have it may have different experiences after consuming the proteins found in cow's milk. If you’re ever concerned that your little one may have it, don’t hesitate to contact your pediatrician.

Key Insights: "How Do I Know If My Baby Has a Cow's Milk Allergy?"

Common Indicators: Colic, bloody stools, eczema, vomiting, diarrhea, gas, or bloating; skin reactions, coughing or wheezing may also occur.
Behavioral Clues: Fussiness, irritability, or excessive crying after feeding could signal a reaction to cow milk proteins. These behaviors often appear shortly after eating.
Confirmation: Your pediatrician may recommend eliminating cow milk protein from your baby’s diet to monitor changes. Skin prick or blood tests may also be used to confirm an allergy.
Next Steps: Ask your pediatrician about switching to a hypoallergenic formula.

Cow’s Milk Protein Allergy Indicators

Indicator	Description
Colic	Prolonged crying (more than 3 hours/day, 3 days/week, for 3+ weeks) in an otherwise healthy baby. Often worse in the evening or night.
Nausea or vomiting	Your baby could feel sick or might vomit excessively.
Reflux	Some babies have more severe reflux, spitting up large amounts, forcefully vomiting, choking, gagging, arching away from the bottle or breast, seeming irritable during or after feeding, or struggling to gain weight.
Diarrhea or unusual poops	Diarrhea can be frequent, watery, foul-smelling loose poops—especially concerning if the baby becomes dehydrated. Breastfed baby poop is usually runny and seedy; formula-fed baby poop is typically thicker. If you notice blood and/or mucus in the stool, contact your doctor right away.
Gassiness	A bloated or firm stomach, clenched fists, stiff or pulled-up legs, and frequent passing of gas can indicate discomfort.
Constipation	Hard, pellet-like stools or infrequent bowel movements. Note: some healthy infants may go for several days without pooping.
Hay fever-like indicators	Sneezing, and an itchy, runny, or blocked nose may be signs of a reaction to cow’s milk.
Anaphylaxis	A rare but serious allergic reaction: indicators include difficulty breathing, fainting, facial swelling, and full-body skin irritation. Seek emergency medical help immediately (call 911).
Eczema or rash	Small red bumps on the face, scalp, hands, or feet that may itch, ooze, crust over, or feel dry and scaly.

Cow’s Milk Allergy Vs. Dairy Sensitivity Vs. Lactose Intolerance

Some cow milk allergy indicators, such as gassiness and diarrhea, are similar to dairy sensitivity indicators. However, cow’s milk allergy, dairy sensitivity, and lactose intolerance are all different.

Food allergies involve the immune system, and in the case of a cow's milk allergy, the body's immune system triggers an adverse response to the protein in cow's milk.

Lactose intolerance in babies and lactose sensitivity have to do with an inability to fully break down or digest lactose, milk sugar. If you're unsure if your child has sensitivity vs CMPA, talk to your pediatrician about the issues your baby is experiencing.

Understanding the Steps to a Cow’s Milk Protein Allergy Identification

If you suspect your baby may have a cow milk protein allergy, following these steps could make identifying the allergy a bit easier, but remember, any number of things could be causing your baby’s behaviors, so it’s best to consult your pediatrician.

Start keeping a diary of your baby’s issues.

Note whether your little one flares up during or after feeding or at certain times of the day.
Keep track of indicators for over 1–2 weeks.
Track which foods your baby is consuming—breast milk, formula, or solids.
Note if your baby gets upset when you try to nurse or offer a bottle or whether they seem uninterested in eating even when you know they’re hungry. Bring your diary to your pediatrician's appointment to discuss your concerns together.

2. Prepare questions for your pediatrician.

3. Test and learn. To confirm if your little one has a cow milk allergy, your doctor may suggest an elimination of diet and food challenge guided by them or another health care professional, such as a dietitian. A skin prick or blood test may also be recommended to gather more data about the body’s immune responses. Do not perform a food challenge on your own –be sure to consult with your doctor first.

4. Your doctor may suggest specific dietary changes. If you’re breastfeeding, ask your doctor if you should take cow milk out of your diet. If you’re formula-feeding, you may be advised on suitable hypoallergenic formulas.

5. If your baby continues to have issues, your pediatrician may refer you to a specialist who can advise you on further next steps or look into other food allergies.

Always speak to a doctor if you’re ever worried about your baby’s health. Get immediate medical help if your baby has trouble breathing, seems faint, or has swelled around their mouth and face.

Cow’s Milk Allergy Management

If your doctor suspects cow milk allergies, they may suggest eliminating cow milk proteins from your baby’s diet. This isn't as daunting as it might sound.

For breastfed babies

Cow milk protein fragments can be passed in breast milk when the mom consumes dairy products. Breast milk still provides the best nutrition for your baby, so you shouldn't stop nursing. You should not remove dairy foods from your diet without speaking to your doctor.

For formula-fed babies

Switching to a hypoallergenic, extensively hydrolyzed formula designed for babies with cow milk allergy may help. Some infants experience a reduction in excessive crying due to colic as early as 24 hours after the switch. Other cow milk allergy indicators—like eczema, reflux, vomiting, and diarrhea—may take longer to improve and are often seen after 3–6 weeks of continued feeding.

As your baby gets older, your doctor may suggest you start reintroducing your child to foods made with cow milk. This should always be done carefully and under a doctor's supervision. Most children outgrow cow's milk allergy eventually,1 so you may not be facing a lifetime of saying no to your child's pleas for ice cream and mac and cheese. In the meantime, there are other ways you can manage CMPA, and the indicators associated with it.