Cow's Milk Protein Intolerance
What is cow’s milk protein allergy (CMPA) in the breastfeeding baby? CMPA is a reaction that your baby might have after you eat or drink dairy products (products containing cow’s milk). Common products are milk, ice cream, butter, cheese or yogurt. Most infants with CMPA have a delayed or non-IgE reaction of 2-48 hours after exposure to dairy products. These symptoms may include slow weight gain, wheezing, spitting up, diarrhea (sometimes bloody), constipation, rash, red bottom, eczema, stuffy nose or fussiness. If your baby has any of these symptoms, you or your healthcare provider may suspect dairy products are the cause. Dairy products are the most common cause of allergic reactions.1
In exclusively breastfed babies, other foods may also cause reactions. You may want to keep a food diary for a few days to chart the foods you are eating. For example, the culprit could be soy, eggs, wheat, or other foods. Occasionally, even chocolate or coffee may cause upsets. Sometimes parents must also be detectives!
In exclusively breastfed babies, other foods may also cause reactions. You may want to keep a food diary for a few days to chart the foods you are eating. For example, the culprit could be soy, eggs, wheat, or other foods. Occasionally, even chocolate or coffee may cause upsets. Sometimes parents must also be detectives!
Rarely, immediate symptoms (known as an IgE mediated reaction) occur within minutes to two hours of ingesting dairy containing foods. Symptoms may include swallowing and/or breathing difficulties (anaphylaxis). If you observe an immediate reaction, this is an emergency. Consult emergency services immediately!
CMPA is more common in babies who have been exposed directly to cow’s milk formula. Cow’s milk protein is present in large amounts in standard infant formula. Where possible, removing formula from their diet is the first, most important step.
Dairy products that you consume pass through your breastmilk to your baby in much smaller, trace amounts. Exposure to these tiny trace amounts through breastfeeding may help your baby develop tolerance to cow’s milk protein.2,3 In extreme circumstances, removing dairy products from your diet may be needed to improve symptoms in your breastfed baby. Most studies have found that the average peak concentration of proteins in breastmilk occurs at around 1-4 hours after ingestion of cow’s milk protein. How long food protein stays in breastmilk varies. However, in general, studies show that peanut and cow’s milk proteins are excreted within hours, often 6-12 hours, and certainly within 24 hours.4 Fortunately, breastmilk has many immune and anti-inflammatory factors which can help a baby’s gut heal and function normally after the initial allergic reaction.
If your baby reacts to dairy products you consume, you might try to eliminate all dairy products from your diet for two to four weeks. See if your baby begins feeling better. Read labels on the foods you are eating. Many countries require that milk products and other common allergens are labelled on ingredient lists. Sometimes milk products may be called casein, whey, or lactalbumin. However, ingredient labelling may not be a requirement everywhere. Some families find removing dairy for everyone makes meal planning easier and helps to avoid accidental consumption.
Sometimes you may be told that your baby is lactose intolerant. All mammals produce milk with lactose sugar. Babies produce the enzyme lactase to break down lactose sugar. Most babies can digest lactose (sugar) in breastmilk without a problem. In fact, lactose is important for baby’s development and brain growth! Lactose intolerance usually shows up later in life, after weaning.
Sometimes if babies are unwell, they temporarily stop producing lactase enzymes. They may have looser, altered stools and discomfort caused by temporary lactose intolerance. Continuing to breastfeed or breastmilk feed your baby is recommended. It helps restore gut function.
A much rarer and serious condition, galactosaemia, is where a baby is unable to digest lactose sugar and needs a medically supervised diet. It is usually diagnosed soon after birth. For more information see https://llli.org/news/breastfeeding-and-galactosemia-2/. This condition is very rare.
If your baby improves when you eliminate dairy products, you will still need to make sure you eat enough calcium. Almonds, Brazil nuts, broccoli, calcium fortified orange juice, and other foods are rich in calcium. Ask your healthcare provider about calcium supplements, and, if recommended, which type would be best for you. In some countries, cow’s milk also is an important source of iodine which may be lost if you don’t consume dairy products. Eggs, fish, seaweed and iodized salt are other sources of iodine.
Exclusive breastfeeding for about the first six months and continued breastfeeding with complementary foods for two years or longer is the best way to give your baby the very best start in life.5 Your breastmilk is perfect and contains the exact balance of protein, vitamins, minerals, antibodies, oligosaccharides to promote gut health, and all the essential nutrients and protective factors your baby needs.6 Breastmilk is a living fluid which promotes normal function, healing and growth. Many babies continue to thrive despite mothers never identifying what the allergen may be.
References:
1 American Academy of Pediatrics, “Food Allergies and Intolerances in Newborns and Infants”, 2025. Food Allergies and Intolerances in Newborns and Infants.
2 Garcette et al., “Complementary Bottles During the First Month and Risk of Cow’s Milk Allergy in Breastfed Infants”. Acta Paeditricia, Nov 2021. https://doi.org/10.1111/apa.16195
3 Halkan, S., et al., “EAACI Guideline: Preventing the Development of Food Allergy in Infants and Young Children” (2020 Update). Pediatric Allergy and Immunology 32 (2021): 843–858. https://pubmed.ncbi.nlm.nih.gov/33710678/
4 Schocker, F. et al., “Breastfeeding: Maternally transferred allergens in breastmilk: Protective or Sensitizing?” Molecular Nutrition Food Research 2021. https://doi.org/10.1002/mnfr.202200066
https://onlinelibrary.wiley.com/doi/full/10.1002/mnfr.202200066
5 World Health Organization and the United Nations Children’s Fund (UNICEF) “Baby-friendly Hospital Initiative training course for maternity staff: trainer’s guide” (2020). https://www.who.int/publications/i/item/9789240008892
6 Eidelman, A., “Breastfeeding and the Use of Human Milk: An Analysis of the American Academy of Pediatrics 2012 Breastfeeding Policy Statement.” Breastfeeding Medicine 7, no. 5 (2012): 323–324.
Further Reading:
https://laleche.org.uk/allergies/
https://www.lllc.ca/allergies
https://www.cddft.nhs.uk/services/nutrition-dietetics/children/allergies-food-exclusions/CMPA
Anne Eglash, “Duration of Time that Food Proteins are in Breastmilk”, (August 29, 2025 Podcast 3124). https://lacted.org/podcasts/lactfact-duration-of-time-that-food-proteins-are-in-breastmilk/
Published May 2026.
*Adapted from La Leche League International information.
Dairy products that you consume pass through your breastmilk to your baby in much smaller, trace amounts. Exposure to these tiny trace amounts through breastfeeding may help your baby develop tolerance to cow’s milk protein.2,3 In extreme circumstances, removing dairy products from your diet may be needed to improve symptoms in your breastfed baby. Most studies have found that the average peak concentration of proteins in breastmilk occurs at around 1-4 hours after ingestion of cow’s milk protein. How long food protein stays in breastmilk varies. However, in general, studies show that peanut and cow’s milk proteins are excreted within hours, often 6-12 hours, and certainly within 24 hours.4 Fortunately, breastmilk has many immune and anti-inflammatory factors which can help a baby’s gut heal and function normally after the initial allergic reaction.
If your baby reacts to dairy products you consume, you might try to eliminate all dairy products from your diet for two to four weeks. See if your baby begins feeling better. Read labels on the foods you are eating. Many countries require that milk products and other common allergens are labelled on ingredient lists. Sometimes milk products may be called casein, whey, or lactalbumin. However, ingredient labelling may not be a requirement everywhere. Some families find removing dairy for everyone makes meal planning easier and helps to avoid accidental consumption.
Sometimes you may be told that your baby is lactose intolerant. All mammals produce milk with lactose sugar. Babies produce the enzyme lactase to break down lactose sugar. Most babies can digest lactose (sugar) in breastmilk without a problem. In fact, lactose is important for baby’s development and brain growth! Lactose intolerance usually shows up later in life, after weaning.
Sometimes if babies are unwell, they temporarily stop producing lactase enzymes. They may have looser, altered stools and discomfort caused by temporary lactose intolerance. Continuing to breastfeed or breastmilk feed your baby is recommended. It helps restore gut function.
A much rarer and serious condition, galactosaemia, is where a baby is unable to digest lactose sugar and needs a medically supervised diet. It is usually diagnosed soon after birth. For more information see https://llli.org/news/breastfeeding-and-galactosemia-2/. This condition is very rare.
If your baby improves when you eliminate dairy products, you will still need to make sure you eat enough calcium. Almonds, Brazil nuts, broccoli, calcium fortified orange juice, and other foods are rich in calcium. Ask your healthcare provider about calcium supplements, and, if recommended, which type would be best for you. In some countries, cow’s milk also is an important source of iodine which may be lost if you don’t consume dairy products. Eggs, fish, seaweed and iodized salt are other sources of iodine.
Exclusive breastfeeding for about the first six months and continued breastfeeding with complementary foods for two years or longer is the best way to give your baby the very best start in life.5 Your breastmilk is perfect and contains the exact balance of protein, vitamins, minerals, antibodies, oligosaccharides to promote gut health, and all the essential nutrients and protective factors your baby needs.6 Breastmilk is a living fluid which promotes normal function, healing and growth. Many babies continue to thrive despite mothers never identifying what the allergen may be.
References:
1 American Academy of Pediatrics, “Food Allergies and Intolerances in Newborns and Infants”, 2025. Food Allergies and Intolerances in Newborns and Infants.
2 Garcette et al., “Complementary Bottles During the First Month and Risk of Cow’s Milk Allergy in Breastfed Infants”. Acta Paeditricia, Nov 2021. https://doi.org/10.1111/apa.16195
3 Halkan, S., et al., “EAACI Guideline: Preventing the Development of Food Allergy in Infants and Young Children” (2020 Update). Pediatric Allergy and Immunology 32 (2021): 843–858. https://pubmed.ncbi.nlm.nih.gov/33710678/
4 Schocker, F. et al., “Breastfeeding: Maternally transferred allergens in breastmilk: Protective or Sensitizing?” Molecular Nutrition Food Research 2021. https://doi.org/10.1002/mnfr.202200066
https://onlinelibrary.wiley.com/doi/full/10.1002/mnfr.202200066
5 World Health Organization and the United Nations Children’s Fund (UNICEF) “Baby-friendly Hospital Initiative training course for maternity staff: trainer’s guide” (2020). https://www.who.int/publications/i/item/9789240008892
6 Eidelman, A., “Breastfeeding and the Use of Human Milk: An Analysis of the American Academy of Pediatrics 2012 Breastfeeding Policy Statement.” Breastfeeding Medicine 7, no. 5 (2012): 323–324.
Further Reading:
https://laleche.org.uk/allergies/
https://www.lllc.ca/allergies
https://www.cddft.nhs.uk/services/nutrition-dietetics/children/allergies-food-exclusions/CMPA
Anne Eglash, “Duration of Time that Food Proteins are in Breastmilk”, (August 29, 2025 Podcast 3124). https://lacted.org/podcasts/lactfact-duration-of-time-that-food-proteins-are-in-breastmilk/
Published May 2026.
*Adapted from La Leche League International information.
