Food allergies and intolerances in breastfed babies
Food allergies and intolerances in breastfed babies
Post Author
Post Author

Dahlia Rimmon, MS, RDN
Editorial Manager
Medically reviewed by
Medically reviewed by

Nicole Silber, RD, CSP, CLC
Dietitian

Dr. Ali Alhassani, MD, FAAP
Pediatrics and Sleep Training Expert



A quick note before we dive in: if your child ever has severe allergy symptoms like wheezing or difficulty breathing, hives (rash) across their body, fast heartbeat, irritability, or swelling of their lips, mouth, throat, or tongue, these can be signs of a medical emergency. Call 911 right away.
What are food allergies?
Food allergies occur when the immune system reacts to proteins in certain foods and causes an allergic reaction. Although they are most common in infants and children, food allergies can develop at any age. While any food has the potential to cause an allergic reaction, the majority are triggered by nine common allergens:
Cow’s milk
Wheat
Egg
Soy
Sesame
Tree nuts
Peanuts
Fish
Shellfish

Signs and symptoms of a food allergy
Skin reaction: Hives, itching, rash with bumps, swelling of the face, mouth, and lips.
Breathing reaction: Sneezing, wheezing, difficulty breathing, anaphylaxis.
Stomach reaction: Abdominal pain, nausea, vomiting, diarrhea.
Symptoms of a food allergy can range from mild to severe and typically appear soon after eating the allergenic food (a reaction can occur within minutes). Any reaction that interferes with breathing is a medical emergency and requires immediate attention.
What are food intolerances?
Food intolerances, or sensitivities, are different from food allergies because they do not involve an allergic reaction (no immune response) to a protein. Instead, they typically result from an inability to properly digest or metabolize certain nutrients. In children, this may be due to a congenital or acquired enzyme deficiency. One example is lactose intolerance, where the body lacks lactase, the enzyme required to digest lactose, a sugar found in dairy products. As a result, consuming dairy can lead to uncomfortable symptoms such as bloating, gas, or diarrhea.
Signs and symptoms of a food intolerance
Abdominal pain or discomfort
Gas
Bloating
Nausea
Upset stomach
Rash
Can babies be allergic to breast milk?
Babies aren’t allergic to breast milk itself, but they can react to certain proteins from the mother’s diet that pass into the milk. The most common trigger is cow’s milk protein. Some babies may also react to soy, especially if they have a cow’s milk allergy, due to something called cross-reactivity—where the immune system mistakes one protein (like soy) for another (like dairy).
It's important to note that allergy testing in young infants is unreliable or inconclusive, so it can be challenging to diagnose. “Often it is by process of elimination and monitoring symptoms after removal of the potential allergen or irritant,” explains Nicole Silber, RD, CSP, CLC, Pediatric Registered Dietitian at Summer Health.
Cow’s milk protein allergy (CMPA)
Cows’ milk protein allergies (CMPA) are common in babies. In fact, about 3% of babies in the United States infants develop a food allergy in the first year, and more than half (53%) have a cow’s milk protein allergy. This means babies will have allergic reactions to dairy products and breast milk that contains cow’s milk proteins.
Signs of a milk protein allergy in babies may include:
Blood or mucus in stools
Itchy rash or hives
Swelling on the face, mouth, and lips
Nasal congestion
Vomiting
Diarrhea
Poor growth
Lethargy (extreme sleepiness, tiredness, or low activity)
If your breastfed baby is diagnosed with a cow’s milk protein allergy, you’ll need to eliminate all sources of cow’s milk from your diet or switch to a hydrolyzed infant formula. This requires carefully reading food labels and avoiding all dairy ingredients, including milk, cheese, butter, yogurt, and products containing casein or whey. It's important to be vigilant, as cow’s milk proteins can be found in many processed foods.
How does a mother's diet influence breast milk?
When a mother is breastfeeding, her body prioritizes the nutritional quality of the breast milk, pulling nutrients from her own stores to ensure the baby receives what they need. In fact, if a mother is low in nutrients like calcium or vitamin D, her body may draw from her bones to maintain the milk’s nutritional content. “This is a reason why a good multivitamin supplement is important for breastfeeding mothers,” says Silber. Additionally, trace amounts of proteins from the mother's diet can pass into breast milk, which may trigger allergic reactions or intolerances in sensitive babies.
Elimination diet
Elimination diets are used to help identify food allergies or intolerances by removing specific foods and monitoring for symptom improvement. For breastfeeding mothers, this involves cutting out potential allergens from their diet to see if their baby’s symptoms improve. Cow’s milk and soy are the most common culprits and are usually eliminated first. This process requires paying close attention to food labels, as milk and soy are common ingredients in many processed foods.
If symptoms persist, and under the guidance of a pediatrician, the mother may need to eliminate additional common allergens such as eggs, wheat, peanuts, tree nuts, fish, shellfish, and sesame. Once the baby’s symptoms improve, foods can be reintroduced one at a time to identify the specific trigger(s).
It can take up to four weeks for allergenic proteins to fully clear from both the mother’s system and for a baby’s symptoms to improve. Because the diet can become quite restrictive, it’s important to maintain the mother’s nutritional balance and mental health during this time. Once the baby’s symptoms improve, foods can be reintroduced one at a time to identify the specific trigger(s). Some babies end up being unable to tolerate breast milk (or a full elimination diet becomes too challenging for a mother) and require a hydrolyzed or partially hydrolyzed formula.
Can food allergies or intolerance be outgrown?
Many children can outgrow food allergies as their immune systems mature. The most common allergens that children outgrow by age 5 are milk, eggs, soy and wheat. However, allergies to peanuts, tree nuts, and fish are less likely to be outgrown and often persist into adulthood. Regular follow-up with a pediatrician or allergist can help monitor progress and determine when, or if, it’s safe to reintroduce certain foods.
Oral Immunotherapy (OIT) is a medical treatment supervised by an allergist that aims to help children build tolerance to specific food allergens. Your pediatrician can help determine if your child is a good candidate for OIT and refer you to a qualified specialist.
Can I prevent food allergies in my child?
Early introduction of common food allergens is one of the most effective ways to help prevent food allergies. Current research supports introducing allergenic foods around the time your baby begins eating solids, typically around 6 months of age. Lowering the risk of developing a food allergy includes early exposure and repeated exposure (if there’s no allergic reaction).

FAQs
What are the most common foods that cause allergies or intolerances in breastfed babies?
Cow’s milk and soy are the most common foods to elicit an allergic reaction in babies. .
How can you distinguish between an allergy and intolerance if symptoms overlap?
Often it depends on the context, source, and symptoms. For example, a 2-month-old baby who vomits after every feed may have milk protein allergy, while a 7-year-old who develops belly pain, bloating, or flatulence after every dairy consumption likely has lactose intolerance. A reaction to berries or other non-allergenic foods is likely a food intolerance. If you child has a reaction to any food, consult with your pediatrician for further guidance.
Is eczema a sign of food intolerance and/or food allergy?
Eczema may be a sign of a food allergy.
Is colic related to food allergies or intolerances?
It can be. However, colic is not fully understood, and there are many possible reasons why babies develop colic.
Will gassy foods cause my baby to be gassy?
Not necessarily. While proteins from your diet can pass into breast milk, fiber does not. High-fiber, gas-producing foods like cauliflower or beans typically won’t cause gas in your baby. If your baby does seem uncomfortable after you eat certain foods, it’s more likely due to a protein in that food rather than its fiber content. That said, every baby is different. Some may consistently react poorly to specific foods, even if there's no clear medical explanation. If you notice a pattern, it may be worth removing that food from your diet to see if symptoms improve.
If you have questions about food allergies or intolerances, reach out to your local or Summer Health pediatrician for support. Summer Health is a pediatric telehealth platform offering 24/7 care, providing answers for everything from urgent concerns to everyday questions about your child’s health.
A quick note before we dive in: if your child ever has severe allergy symptoms like wheezing or difficulty breathing, hives (rash) across their body, fast heartbeat, irritability, or swelling of their lips, mouth, throat, or tongue, these can be signs of a medical emergency. Call 911 right away.
What are food allergies?
Food allergies occur when the immune system reacts to proteins in certain foods and causes an allergic reaction. Although they are most common in infants and children, food allergies can develop at any age. While any food has the potential to cause an allergic reaction, the majority are triggered by nine common allergens:
Cow’s milk
Wheat
Egg
Soy
Sesame
Tree nuts
Peanuts
Fish
Shellfish

Signs and symptoms of a food allergy
Skin reaction: Hives, itching, rash with bumps, swelling of the face, mouth, and lips.
Breathing reaction: Sneezing, wheezing, difficulty breathing, anaphylaxis.
Stomach reaction: Abdominal pain, nausea, vomiting, diarrhea.
Symptoms of a food allergy can range from mild to severe and typically appear soon after eating the allergenic food (a reaction can occur within minutes). Any reaction that interferes with breathing is a medical emergency and requires immediate attention.
What are food intolerances?
Food intolerances, or sensitivities, are different from food allergies because they do not involve an allergic reaction (no immune response) to a protein. Instead, they typically result from an inability to properly digest or metabolize certain nutrients. In children, this may be due to a congenital or acquired enzyme deficiency. One example is lactose intolerance, where the body lacks lactase, the enzyme required to digest lactose, a sugar found in dairy products. As a result, consuming dairy can lead to uncomfortable symptoms such as bloating, gas, or diarrhea.
Signs and symptoms of a food intolerance
Abdominal pain or discomfort
Gas
Bloating
Nausea
Upset stomach
Rash
Can babies be allergic to breast milk?
Babies aren’t allergic to breast milk itself, but they can react to certain proteins from the mother’s diet that pass into the milk. The most common trigger is cow’s milk protein. Some babies may also react to soy, especially if they have a cow’s milk allergy, due to something called cross-reactivity—where the immune system mistakes one protein (like soy) for another (like dairy).
It's important to note that allergy testing in young infants is unreliable or inconclusive, so it can be challenging to diagnose. “Often it is by process of elimination and monitoring symptoms after removal of the potential allergen or irritant,” explains Nicole Silber, RD, CSP, CLC, Pediatric Registered Dietitian at Summer Health.
Cow’s milk protein allergy (CMPA)
Cows’ milk protein allergies (CMPA) are common in babies. In fact, about 3% of babies in the United States infants develop a food allergy in the first year, and more than half (53%) have a cow’s milk protein allergy. This means babies will have allergic reactions to dairy products and breast milk that contains cow’s milk proteins.
Signs of a milk protein allergy in babies may include:
Blood or mucus in stools
Itchy rash or hives
Swelling on the face, mouth, and lips
Nasal congestion
Vomiting
Diarrhea
Poor growth
Lethargy (extreme sleepiness, tiredness, or low activity)
If your breastfed baby is diagnosed with a cow’s milk protein allergy, you’ll need to eliminate all sources of cow’s milk from your diet or switch to a hydrolyzed infant formula. This requires carefully reading food labels and avoiding all dairy ingredients, including milk, cheese, butter, yogurt, and products containing casein or whey. It's important to be vigilant, as cow’s milk proteins can be found in many processed foods.
How does a mother's diet influence breast milk?
When a mother is breastfeeding, her body prioritizes the nutritional quality of the breast milk, pulling nutrients from her own stores to ensure the baby receives what they need. In fact, if a mother is low in nutrients like calcium or vitamin D, her body may draw from her bones to maintain the milk’s nutritional content. “This is a reason why a good multivitamin supplement is important for breastfeeding mothers,” says Silber. Additionally, trace amounts of proteins from the mother's diet can pass into breast milk, which may trigger allergic reactions or intolerances in sensitive babies.
Elimination diet
Elimination diets are used to help identify food allergies or intolerances by removing specific foods and monitoring for symptom improvement. For breastfeeding mothers, this involves cutting out potential allergens from their diet to see if their baby’s symptoms improve. Cow’s milk and soy are the most common culprits and are usually eliminated first. This process requires paying close attention to food labels, as milk and soy are common ingredients in many processed foods.
If symptoms persist, and under the guidance of a pediatrician, the mother may need to eliminate additional common allergens such as eggs, wheat, peanuts, tree nuts, fish, shellfish, and sesame. Once the baby’s symptoms improve, foods can be reintroduced one at a time to identify the specific trigger(s).
It can take up to four weeks for allergenic proteins to fully clear from both the mother’s system and for a baby’s symptoms to improve. Because the diet can become quite restrictive, it’s important to maintain the mother’s nutritional balance and mental health during this time. Once the baby’s symptoms improve, foods can be reintroduced one at a time to identify the specific trigger(s). Some babies end up being unable to tolerate breast milk (or a full elimination diet becomes too challenging for a mother) and require a hydrolyzed or partially hydrolyzed formula.
Can food allergies or intolerance be outgrown?
Many children can outgrow food allergies as their immune systems mature. The most common allergens that children outgrow by age 5 are milk, eggs, soy and wheat. However, allergies to peanuts, tree nuts, and fish are less likely to be outgrown and often persist into adulthood. Regular follow-up with a pediatrician or allergist can help monitor progress and determine when, or if, it’s safe to reintroduce certain foods.
Oral Immunotherapy (OIT) is a medical treatment supervised by an allergist that aims to help children build tolerance to specific food allergens. Your pediatrician can help determine if your child is a good candidate for OIT and refer you to a qualified specialist.
Can I prevent food allergies in my child?
Early introduction of common food allergens is one of the most effective ways to help prevent food allergies. Current research supports introducing allergenic foods around the time your baby begins eating solids, typically around 6 months of age. Lowering the risk of developing a food allergy includes early exposure and repeated exposure (if there’s no allergic reaction).

FAQs
What are the most common foods that cause allergies or intolerances in breastfed babies?
Cow’s milk and soy are the most common foods to elicit an allergic reaction in babies. .
How can you distinguish between an allergy and intolerance if symptoms overlap?
Often it depends on the context, source, and symptoms. For example, a 2-month-old baby who vomits after every feed may have milk protein allergy, while a 7-year-old who develops belly pain, bloating, or flatulence after every dairy consumption likely has lactose intolerance. A reaction to berries or other non-allergenic foods is likely a food intolerance. If you child has a reaction to any food, consult with your pediatrician for further guidance.
Is eczema a sign of food intolerance and/or food allergy?
Eczema may be a sign of a food allergy.
Is colic related to food allergies or intolerances?
It can be. However, colic is not fully understood, and there are many possible reasons why babies develop colic.
Will gassy foods cause my baby to be gassy?
Not necessarily. While proteins from your diet can pass into breast milk, fiber does not. High-fiber, gas-producing foods like cauliflower or beans typically won’t cause gas in your baby. If your baby does seem uncomfortable after you eat certain foods, it’s more likely due to a protein in that food rather than its fiber content. That said, every baby is different. Some may consistently react poorly to specific foods, even if there's no clear medical explanation. If you notice a pattern, it may be worth removing that food from your diet to see if symptoms improve.
If you have questions about food allergies or intolerances, reach out to your local or Summer Health pediatrician for support. Summer Health is a pediatric telehealth platform offering 24/7 care, providing answers for everything from urgent concerns to everyday questions about your child’s health.
References
AAP: Food Allergies in Children: Common Causes and Symptoms
Food Allergy Research and Education: Infancy
AAP: Food Allergies in Children: Common Causes and Symptoms
Food Allergy Research and Education: Infancy
AAP: Food Allergies in Children: Common Causes and Symptoms
Food Allergy Research and Education: Infancy
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