Can My Baby Be Allergic to My Breast Milk? Yes. Here's What To Do.

This article was originally posted by Trillitye Paullin, PhD, a molecular biologist and mother to two beautiful daughters with severe food sensitivities. She is the founder of Free to Feed, a place for parents to find answers to their questions about infant food sensitivities and empower them to continue their breastfeeding journey. Trillitye is also available for on-demand advice as an Expert on SocialMama.

So you suspect your breastfed infant has a food intolerance and is reacting to proteins in your breast milk, now what?  First, consult with your pediatrician and determine if referrals to an allergist or gastroenterologist are warranted.  In conjunction with your medical team, the following steps can help guide your journey. 

Does my baby have food intolerance/allergies?

Before jumping into a game plan, lets discuss what warrants it in the first place. The following symptoms can be indicative of an infant food intolerance or allergy: reflux, vomiting, rash, eczema, diarrhea, constipation, mucous stool, bloody stool, failure to thrive, colic, lethargy, and airway restriction [1].  Since these range widely, it is important to consider other contributing factors such as teething, vaccines, or illness before taking action to fix a food problem that may not exist.  Additionally, some symptoms which exist solely, such as reflux or colic, may not be attributed to food allergies and options should be discussed with your medical professional.  Commonly, two or more symptoms occur when baby is reacting to dietary proteins in your breast milk [1].

Taking Action

This is not a one-size-fits-all medical issue.  The best course of action is different for every mother, infant, and family situation.  Here, we outline two courses of action: removing one food at a time or removing all common culprits at once from a mother's diet.  The reason why these two approaches are recommended are based on the pros and cons of each.  When removing only one at a time, it is much easier to tell which is the offending food and it can be much easier on mom.  Conversely, removing several foods at once can help baby recover faster from symptoms but it will take longer to deduce which items are the problem and such a restrictive diet can be difficult for mom. 

Consideration 1: Symptoms

These decisions are often based on symptom severity.  Milder symptoms can often be addressed by trialing individual protein elimination until identifying the culprit.  Severe symptoms are best addressed by removing most possible culprits and slowly adding back one at a time after symptoms have subsided.  For example, a family whose infant has reflux and mucousy stool may want to trial one at a time while a case of severe bloody stool, projectile vomiting, and constant colic may decide to take the second approach and remove several things at once. 

Consideration 2: Dietary Ability

Everyone’s food situation is different.  Mothers who plan to remove many food items at once need to consider their nutritional needs and the availability of alternative foods.  A helpful outline on less-allergenic food substitutions with similar minerals and vitamins can be found here.  Maternal malnutrition is a significant concern if mom cannot access or afford different foods to bridge the nutritional gap. 

Consideration 3: Mental Health

There are two opposing maternal mental health considerations.  On one hand, continued infant symptoms can be frustrating, depressing, and worrisome.  On the other, excessively restrictive diets can be frustrating, depressing, and worrisome.  See a theme here?  It is vital that moms choose a path which is feasible for their long-term mental health.  Breastfeeding is wonderful, but having happy parents is wonderful too.  Awareness is key. 

How to Remove Individual Foods From Your Diet

When removing an individual food item, understanding timing is vital.  What to cut, how long to cut, and if/when to cut the next thing are main questions.  Each answer will depend on your situation.  We have outlined the top infant food intolerances/allergies below.  This is in order of prevalence, so start at the top of the list and choose what to eliminate based on experience.  If you are a strict vegan, skip on down to soy as you have already eliminated dairy.  If you consume dairy (even lactose free), start there. 

Research indicates that ingested food proteins peak in breast milk concentration in approximately 2 hours and steadily decrease from there.  While there are always outliers, most ingested proteins will clear mother’s system within 24 hours

The next part of the equation is infant symptoms.  How long it will take to see improvement varies greatly depending on infant sensitivity and length and quantity of exposure (a lot of soy over a long period of time versus a little in a short period).  Read this article about allergy timing to better understand how this all works.  Essentially, complete healing can take several weeks.  That being said, if you have indeed removed the real allergy food you should see either a plateau (same) or an improvement in symptoms within a week. 


The biggest misstep in this process is moving on to the next food without properly removing the current target.  Imagine, you have eliminated dairy and see steady increase in symptoms instead of improvement.  You decide to remove soy, then egg, then wheat…on and on.  Several months or weeks go by without improvement when it suddenly dawns on you that your [insert surprise here] contains dairy.  Back to square one.  That is why it is sooooo important to ensure heavy scrutinization of everything you ingest before removing the next item.  Beverages, supplements, medications, and seasonings are common hidden allergen sources [2].  Keeping a detailed food log during this time can help you pinpoint hidden allergens or what your next target should be.