Breast Milk Sensitivity

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What you need to know

​​Can a baby be allergic to breast milk?

Research shows that a mother's milk is only slightly affected by the foods she eats. Breastfeeding mothers can eat whatever they have eaten during their lifetimes; they do not need to avoid certain foods. Babies love the flavors of foods that come through in your milk. Sometimes, though, a baby may be sensitive, not allergic, to something you eat, such as dairy products like milk and cheese.  Soy, eggs, wheat, corn, beef and nuts are also common causes of food sensitivity. Talk with your baby's doctor if you think your baby is sensitive to something you are eating.

Food allergy versus food intolerance

There is a difference between a food intolerance and having a food allergy.  To find out more, please see: American Academy of Allergy Asthma & Immunology.

Milk intolerance

Cow's milk protein is one of the most common causes of food sensitivity in a baby who is breastfeeding. Cow's milk protein intolerance is a reaction by the body's immune system to a protein found in cow's milk. A milk allergy or milk protein intolerance is different from lactose intolerance. People who are lactose intolerant do not have the ability to break down lactose, the sugar present in milk and dairy products.  If the baby is sensitive to dairy in your diet, lactose free dairy products will not help. Milk is in many foods in our diets.  Removing milk and milk products in the diet is the first line of treatment. Many infants will have an intolerance to soy proteins as well.

Soy intolerance

Soy is the second most common cause of food sensitivity in a baby who is breastfeeding. Typically, soybeans alone are not a major food in our diets, but soybeans are widely used in the many processed food products we eat.  Soybeans are a member of the legume family, and are widely used in processed food. They are broken down into a powder or oil and added to commercially prepared foods to provide protein and flavor.  It is best to read all product labels carefully before purchasing and eating them.

Other food sensitivities

Eggs, wheat, corn, beef, and nuts are also common causes of food sensitivity. Table 1 and Table 2 list information regarding ingredients on labels to avoid if your baby has a food sensitivity or allergy. 

MSPI Food Graph for milk and soy food label ingredients.

Other Food Graph for eggs, wheat, corn, peanuts and nuts food label ingredients.


Milk Soy Protein Intolerance (MSPI)

MSPI is a temporary intolerance to the proteins in milk and soy. Both breast-fed and formula-fed babies can develop an intolerance to cow's milk and / or soy proteins. “As many as 2 to 7% of babies under one year of age have intolerance to cow's milk, and in our area, 60% of those babies will also develop intolerance to soy proteins."(7) A food intolerance may often run in families, with more than one child or a parent needing a special diet. 

It is unclear why MSPI is more frequently seen in the Midwest Regions of the United States. Other regions across the United States may possibly call it by another name like cow's milk protein intolerance (CMPI), food protein induced colitis, or allergic colitis. 

MSPI symptoms

Food sensitivity symptoms vary from infant to infant.  The symptoms can include:

  • ​fussiness or excess crying before, during and after a feeding
  • ​stools may be infrequent, watery, have mucous, or be bloody
  • ​reflux
  • ​spitting up
  • ​nasal congestion
  • ​skin rash, eczema, hives, dry skin
  • ​weight loss
  • ​repeated vomiting
  • ​sudden waking with discomfort

These signs do not mean the baby is allergic or sensitive to your breast milk itself, only to something you are eating. Babies who are highly sensitive usually react to the food the mother eats within minutes or within 4 to 24 hours afterwards. Some symptoms show up 3 to 4 days later. If you stop eating whatever is bothering your baby, the problem usually goes away on its own. Talk with your baby's doctor about any symptoms.

If your baby ever has problems breathing, call 911 or go to your nearest emergency room.

The baby's symptoms should improve within as little as 3 to 7 days after removing the food intolerant from mom's diet. It may take up to two weeks for the baby's stomach / intestines to heal from any irritation caused by the intolerance. Cow's milk protein can stay in mom's body for 1 ½ to 2 weeks, and then it may be another 1 ½ to 2 weeks for the protein to get out of the baby's system.

Fussiness is one of the most common symptoms of a food sensitivity or intolerance.  Fussiness before eating because of hunger, during the feeding and then more fussy as they become more uncomfortable can be common. “Children with MSPI may cry 18 hours or more a day and may develop weight loss, congestion, repeated vomiting, reflux, and certain kinds of skin rashes. They also may have changes in appetite, including refusing food or wanting to eat all the time, irritability / fussiness, and blood or mucous in their stools."(7) Some babies frequently “grunt" as if they are having a hard time passing stool, but stools are soft. This may be a sign of intestinal inflammation.

Diagnosis and treatment

Diagnosing MSPI is sometimes difficult, as there is not a definite test. Diagnosis is mainly by reviewing the history of the baby's symptoms and a dietary trial without milk and / or soy products. Your baby's physician may check for blood in the baby's stool.

Treatment: There is no medication to treat MSPI or a food sensitivity. As a treatment, the breastfeeding mom removes the food intolerances from her diet. Committing to a strict, time-consuming diet is challenging but worthwhile. Continuing to breastfeed is still the best nutrition for your baby and the immunities breastfeeding provides will assist in the healing process for your baby. A variety of foods are available by making recipes from scratch, substituting milk/dairy and soy-free products. “Babies with MSPI also do better if solid foods are not introduced until around 6 months of age. At that time, solid foods can be introduced in a slightly different order than for babies without MSPI."(7) Ask your healthcare provider in what order to introduce solid foods.


Talking with a dietician early on or prior to starting a food-restricted diet is very beneficial. The dietician can direct you to certain food items and brands that are milk and soy free, and help find hidden sources of dairy and soy in foods and drinks. The dietician will also make sure you are getting the nutrients that you need while breastfeeding and suggest non-dairy food sources of calcium.  Bring a family member or friend with you to your visit to make sure all your questions and concerns are answered, and to educate them on what foods you can eat.

Keeping a food log will also help the dietician locate hidden sources.  It is very important to keep a food log of everything you eat and drink along with the baby's symptoms.  In some babies, it may take 3 to 4 days for the symptoms of intolerance to a food to show up. You can then look back for any new item you ate or drank to locate the cause of the symptoms.

Some new moms find a strict food diet very overwhelming. If you are feeling anxious, overwhelmed or struggling emotionally, please talk with your physician. Joining a MSPI support group is very beneficial as you receive emotional support and helpful hints about food, recipes, and restaurants. There are several Facebook MSPI groups that are helpful and supportive.

Formula-fed babies must switch to an expensive dairy and soy free formula. “These formulas are made up of broken down proteins and are able to be digested without an immune reaction. These formulas will work in 90% of patients with a cow milk protein intolerance."(3)

“Most infants that are started on cow's milk-free formulas or breastfed by a mother on a cow's milk-free diet will need to remain on the diet for about 6-12 months. At that point, the child can be challenged with cow's milk, and if they have no reactions, milk can be put back into the child's diet."(7) Check with your baby's doctor about when to introduce milk and soy into their diet. If breastfeeding, introduce the milk or soy product to the baby to see if there is a reaction. If you eat the milk or soy product, it will be in your breast milk for a longer period of time. 

Food label reading

Food Labels are required to state if a food product contains one or more of the eight major food allergens: peanuts, tree nuts, milk, egg, wheat, soy, fish, and shellfish.

The label must include the allergen in the ingredient list or state that it “may contain" or “processed in a facility that processes" or “processed on equipment with" the allergen.

Read all product labels carefully before purchasing and eating them.  This takes time at first, but becomes easier as you get used to looking for certain ingredients. Products and ingredients can change without warning, so read every label, every time.

Eating out

Eating out at a restaurant is a challenge while on a food sensitivity diet. Plan ahead before you go out:

  • Check the restaurant website for a list of allergy contents;
  • Call the restaurant (avoid busy meal times) and speak to the manager or chef to inquire about how they prepare dishes and the oils they cook with.  Some meat products are cooked in butter.  Ask to see/check the labels of their prepackaged food;
  • Be specific when requesting food preparation, and tell them about the food sensitivities of your baby;
  • Ask if you may bring your own salad dressing in;
  • Check all foods. If you order a sandwich like a hamburger, the hamburger patty may be ok to eat but the bun may not.


Food and food products are constantly changing, manufacturers may change their products without notice. Always read the label. Check medication and vitamin labels as well, as they may contain milk or soy ingredients.  Some of your own favorite recipes can be made milk and soy free, by using milk and soy free products. Find more information for food, recipes and other subjects at Breastfeeding Resources.


Documents used in the development of this content:

  1. Breastfeeding and everyday life. [Online] January 20, 2015 
  2. About Food Allergies  FARE Food Allergy Research & Education [Online] July 24, 2014
  3. Cow's Milk Protein Intolerance  GI Kids [Online] August 14, 2014  
  4. Otto, Elizabeth Soy Protein Intolerance Symptoms [Online] 12 31, 2014 
  5. Dairy and other Food Sensitivities in Breastfed Babies [Online] August 14, 2014 
  6. ABM Clinical Protocol #24: Allergic Proctocolitis in the Exclusively Breastfed Infant Medicine, The Academy of Breastfeeding 2011, Breastfeeding Medicine, pp 435-440 
  7. What is MSPI?  Complete Children's Health [Online] August 21, 2014  
  8. Milk (and Soy) Free Diet for the Breastfeeding Mother  Lincoln Pediatric Group [Online] August 14, 2014 
  9. Recognizing Cow's Milk Protein Allergy in Infants - Evidence Shows Eliminating Milk and Soy Can Help Judith C Thalheimer, RD, LDN 2012, Today's Dietitian, p 14 (Vol 14 No 3 P 14) 
  10. Diagnosis and management of cow's milk protein allergy in infants Elisabeth De Greef, Bruno Hauser, Thierry Devreker, Gigi Veereman-Wauters, Yvan Vandeplas 1, Brussels, Belgium: World Journal of Pediatrics, 2012, Vol 8
  11. Gastrointestinal Food Allergy in Infants  Hideaki Morita, Ichiro Nomura, Akio Matsuda, Hirohisa Saito, and Kenji Matsumoto 3, sl : Allergology International, 2013, Vol 62
  12. Infant Food Allergy: Where Are We Now Joneja, Janice M 49S, sl: Journal of Parenteral and Enteral Nutrition, 2012, Vol 36
  13. A Review on the Diagnosis and Management of Food-induced Gastrointestinal Allergies R Meyer, C Schwarz, N  Shah 1, sl : Current Allergy & Clinical Immunology, 2012, Vol 25 ​