Is your baby reacting to something in your milk?

AngelaRD, LDN, CBS

Read time: 8 minutes

What should I know about an allergy or intolerance in my breastfed baby?

  • Learn the difference between an allergy and a food intolerance or sensitivity
  • Know the signs and symptoms of food allergy or intolerance in breastfed infants
  • Learn which foods are the most common allergens or culprits in food intolerances
  • How to manage your food intake to help alleviate your baby’s symptoms

Breastmilk is incredible – it offers a complete form of nutrition for infants, and offers a range of benefits for health, growth, immunity, and development.1 The nutrients in your breastmilk come directly from what’s circulating in your blood, meaning that the nutrients and compounds you absorb from the food you eat are then passed along to your baby.

While being truly allergic or reacting to something in mom’s milk is rare in babies, a small percentage of mothers do notice a difference in their babies’ symptoms or behavior after eating certain foods.

What’s the difference between an allergy and an intolerance or sensitivity? 

Sometimes these terms are used interchangeably, but an allergy and an intolerance/sensitivity are very different.  According to the American Academy of Allergy Asthma and Immunology (AAAI), an allergy is when the immune system reacts to a food, whereas an intolerance happens during digestion.2  Allergies generally have more severe symptoms, often causing skin reactions or difficulty breathing.  Food intolerances occur when we have difficulty digesting a food, which often result in gastro-intestinal symptoms.

With an allergy, the culprit food often needs to be taken out of the diet completely to avoid symptoms.  Food intolerances however may allow for a small amount of the offending food to be eaten without any reactions.  This is the ‘threshold’ amount: the lowest amount of the food you can eat without having symptoms.

Read more: Major Allergens: While Pregnancy and Breastfeeding

Which foods might cause an allergic reaction?

In general, food allergens include cow’s milk, soy, eggs, peanuts, wheat, tree nuts, fish, and shellfish.3  In children, the most common allergens are peanuts, milk, tree nuts, and shellfish.4, 5

What are the symptoms of a food allergy in babies?

Food allergies affect about 7.6% of children in the United States.4

The most common symptoms of an allergy in breastfed infants are eczema (a scaly, red skin rash) and bloody stool (with no other signs of illness). You might also see hives, wheezing or other breathing problems, nasal congestion, swelling of a body part (tongue, lips, face), throat tightness, pale skin, vomiting or diarrhea.6

If you notice any of these symptoms, be sure to call baby’s pediatrician right away. While you can likely manage most food allergies in your breastfed infant by changing your diet, there are some cases in which using a hypoallergenic formula may be required.

Here are some tips for Managing Gas in Breastfed Babies

Which foods might cause a food intolerance or sensitivity reaction?

You may have heard that eating foods that make you gassy will also cause gastrointestinal distress for your baby, or that eating foods like onion, garlic and cruciferous vegetables will cause colic. While there is no significant data to support such an association, there are some mothers who do notice certain foods make their babies fussier than usual.  This may be a food intolerance or sensitivity.

There is a much wider variety of foods that may trigger a reaction when it comes to food intolerances; but it’s important to note that food sensitivities in babies are much less common than food allergies.

Foods that may cause reactions include: Fructose, lactose and other FODMAPs (easily fermented carbohydrates found in a variety of foods), wheat, histamine (often found in processed meats, cheeses, and some produce), and food additives.7

What are the symptoms of a food intolerance in babies?

The most common symptom of a food sensitivity in babies is a change in their bowel habits.  Extra gas, bloating, diarrhea or constipation, fussy after eating, mucous in the stool, or crying excessively may indicated baby is not doing well with a food you’re eating.

Note that if your little one has excessive crying that continues on a daily basis and lasts for long periods, that may indicate colic rather than food sensitivity.8 Talk with your pediatrician about this possibility, if eliminating various foods has no effect on your child’s symptoms.

Read: Managing Colic in Babies

What can I do if my baby is reacting to something in my diet?

The ultimate goal is figuring out which food is affecting your baby.  An elimination diet can help identify which food may be causing the allergy or food sensitivity.9 This means removing possible allergens from your diet for 2 to 3 weeks each while you continue breastfeeding.

There are two ways to go about an elimination diet:

Take out one potential allergen or intolerant at a time: If there is one food strongly suspected as the culprit, you can choose to take out just that one food. Watch to see if your baby’s symptoms subside. Should baby’s symptoms get better, keep that food out of your diet.  If baby’s symptoms remain the same over the course of 3 weeks, you can begin eating that food again and then eliminate a different allergen.

Take out all potential allergens or intolerants at once: If you are unsure which food is causing the problems, all allergens or possible culprit foods can be taken out for the 2 to 3 weeks and then added back in one at a time.

For a possible food intolerance or sensitivity, add one food back in over the course of 3 days – this is the challenge period. The first day eat a small amount, the second day eat a medium amount, the third day eat a larger amount.  Doing it this way shows you if baby has a threshold.  Sometimes you can eat a small amount of an offending food without it bothering your little one.

Remember that for a food allergy, it is likely the food must be taken out completely from your diet.

If your baby shows symptoms during any of the challenge days, stop the challenge and take the food back out of your diet.  Don’t trial a new food until all your baby’s symptoms are gone.  If there are no symptoms during the challenge period, you can eventually eat this food again! For now, take it back out of the diet after its 3 day challenge and wait to add it back in after you’ve challenged all culprit foods.10

Keep a good log of the foods you’ve challenged, symptoms, and amounts you’ve eaten!

You can continue breastfeeding despite the symptoms as long as your baby continues to grow and put on weight during this process.

If you plan on trying an elimination diet, especially a multi-food elimination, be sure to work with a registered dietitian. This will help ensure you are still getting all the nutrition you and your baby need as well as help navigate hidden sources of allergens.  Foods like milk, soy, and corn can hide in all sorts of pesky places.

Our Happy Baby Experts are dietitians and infant feeding specialists, they can help you meet your breastfeeding goals while keeping both you and baby happy and healthy.  Chat with them now!

Trying to figure out what to eat while also taking out all allergens? Check out this Meal Plan for Allergen Free Eating. 

Does breastfeeding help protect against allergies?

While more research is needed, some studies have indicated that breastfeeding exclusively for at least four months may help to reduce the risk and severity of food allergies, even in families with a history of them.11, 12

So if your little one does show an intolerance or allergy early, know that it may resolve on its own before they turn one and that continued breastfeeding may help to safeguard against allergies later on.

What should I do if baby is reacting to my breastmilk?

Contact your pediatrician

Bring your baby in for a checkup. You’ll want to rule out any other causes for her symptoms, check baby’s growth and weight gain, and make sure baby is not losing excessive blood if your little one experiencing bloody stool. Your doctor can also discuss the possibility of confirming the presence of an allergy with a skin prick test.

If your child is diagnosed with a food allergy, remember to ask about reintroducing the food later. Most kids will grow out of food allergies, sometimes by their first birthday.

Keep a food and symptom journal

We know it’s hard to find time to eat in those first few months, let alone write down what made it into your mouth, but tracking your intake alongside your baby’s symptoms is a good way to shed light on any possible reactions.

Just remember that foods we eat remain in our bodies for long periods of time. So while a journal can be helpful to pinpoint the onset of symptoms when you first eat the offending food, know that your baby’s symptoms can persist for several days or up to 2 weeks, even if you don’t eat that particular food again.

Try an elimination diet

If you notice an adverse reaction in your baby after you eat certain foods, try removing that food from your diet and watch for improvement.

Start with cow’s milk. The most frequent allergic reaction in breastfed babies is a milk protein allergy.5 Remember, it takes time for your body to be completely free of the offending food, so make sure you’ve removed all sources of the food for at least two weeks.

Seek support

Changing your diet can be hard.  Finding a registered dietitian who can help make adjustments to your diet will help take some stress out of this process.   Additionally, may lactation consultants are familiar with helping make these adjustments as well and also ensuring baby is getting what they need.

Let’s Chat!

We know parenting often means sleepless nights, stressful days, and countless questions and confusion, and we want to support you in your feeding journey and beyond.

Our Happy Baby Experts are a team of lactation consultants and registered dietitians certified in infant and maternal nutrition – and they’re all moms, too, which means they’ve been there and seen that. They’re here to help on our free, live chat platform Monday through Friday, from 8am–6pm ET, and Saturday and Sunday, from 8am–2pm ET. Chat Now!

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