How to Introduce Common Food Allergens to Your Baby

The first six months of your baby’s life are so exciting to witness—your newborn learns to grasp, sit up independently, and reacts to you with laughter and smiles. And in the blink of an eye, your baby reaches another major milestone: eating solids.

If introducing solids weren’t nerve wracking enough, your pediatrician will recommend exposing your baby to common food allergens, as well. Why? Because an early introduction to allergens is the best way to prevent or minimize your child’s allergic reactions in the future. Here’s everything you need to know about safely introducing food allergens to your new eater.

What Causes a Food Allergy?

A food allergy is caused by your body having an abnormal immune response to certain proteins found in specific foods. When someone with an allergy consumes, touches, or inhales the allergenic food, their immune system mistakenly identifies these proteins as harmful substances, and produces an antibody called immunoglobulin E (IgE) to defend against them. Copies of IgE move through the blood and attach themselves to two kinds of cells in the immune system (mast cells and basophils).

When someone with IgE eats or comes into contact with the same food allergen again, the allergenic proteins bind to the IgE antibodies, triggering a flood of chemical substances that cause the telltale signs of a food allergy (skin rashes, itching, swelling, and breathing difficulties).

Why do some people develop food allergies while others don’t? While the specific individual cause isn’t entirely understood, these factors can contribute to their development:

Genetic predisposition. If your family has a history of allergies (and not just food allergies—asthma or seasonal allergies, as well), you may be more likely to develop food allergies.
Immune system dysfunction. An overactive immune system may be more likely to produce an allergic response to harmless substances like food proteins.
Delayed exposure to allergenic foods. New research suggests that early introduction of allergenic foods while first transitioning your baby to solids can help prevent or minimize allergic reactions later.

Keep in mind that food intolerances, like lactose or gluten intolerance, are different from food allergies. Food intolerances do not typically involve the immune system, and instead are caused by an inability to digest certain substances.

What Are the Most Common Food Allergens?

The Food Allergen Labeling and Consumer Protection Act of 2004 (FALCPA) identified nine foods as major allergens:

Milk. Allergy to cow’s milk is one of the most common food allergies, especially in babies and young children. Remember, a milk allergy is different from lactose intolerance, which is the inability to digest lactose (the sugar found in milk).
Eggs. Egg allergies are especially common in children, but most kids outgrow having an allergic reaction to eggs by the time they’re five.
Fish. Fish allergies are more common in adults than children, and an allergy to one type of fish can also indicate an allergy to other types, as well.
Shellfish. Shellfish allergies are also more common in adults, and this includes both crustaceans (shrimp, lobster, and crab, for example) and mollusks (clams, oysters, scallops, and mussels, for example).
Tree nuts. Tree nut allergies are common and aren’t usually outgrown. This includes almonds, walnuts, cashews, and pistachios.
Peanuts. Peanut allergies are generally lifelong, and can be quite severe. Though peanuts are often grouped in with tree nuts, they’re actually a legume—so being allergic to peanuts doesn’t necessarily mean you’d be allergic to a pecan.
Wheat. Wheat allergies are more common in children, and are typically outgrown by adulthood.
Soybeans. Soy is an incredibly common food allergy in infants and children, and an ingredient that’s found in many processed foods, so label-checking is essential. Fortunately, most soy allergies do not persist into adulthood.
Sesame. Sesame is also a very common childhood allergy, and if your child has a sesame allergy, it’s likely they have other food allergies, particularly to tree nuts, as well.

Keep in mind that these are the most common food allergens, but there are other uncommon allergens that can also cause reactions. If you suspect a food allergy, it’s always best to consult with your healthcare provider to undergo the steps necessary for diagnosis and guidance on managing the allergy.

When Should You Introduce Solids to Your Baby?

Before introducing your baby to solid food (including allergens), it’s smart to brush up on the American Academy of Pediatrics (AAP) recommendations. The AAP recommends exclusive breastfeeding for the first six months. Once your baby approaches their half birthday, start looking for signs of readiness, including:

Your baby sits up alone, without support.
Your baby demonstrates head and neck control.
Your baby opens their mouth when food is offered.
Your baby doesn’t automatically push anything out of their mouth with their tongue (loss of the tongue thrust reflex).
Your baby brings objects to their mouth.
Your baby tries to grasp small objects.
Your baby is very interested in watching other people eat.

If you can answer “yes” to most of these questions, your baby is ready to start solids. And don’t forget—timing matters. Plan to introduce food when your baby is happy, not overly hungry, and not tired (generally an hour or so after breast or bottle feeding).

When Should You Introduce Food Allergens to Your Baby?

In 2019, the American Academy of Pediatrics (AAP) updated a clinical report on infant and childhood allergies—it concluded that introducing common allergens (like peanuts, eggs, and fish) early while transitioning to solids helps prevent or minimize allergic reactions later.

In other words, plan to include common food allergens as soon as you begin introducing solids. Just make sure you’re preparing them in a developmentally appropriate manner (your new eater can’t chew and swallow as well as a toddler, so you will need to thin peanut butter with breast milk or formula, for example).

How to Introduce Food Allergens to Your Baby

Consider your family history. Your baby is at higher risk for food allergies if anyone in your baby’s family has a history of allergic diseases (like asthma, eczema, hay fever, or atopic dermatitis). And if your baby has severe eczema themselves, they may be at a higher risk for food allergies, too.
Timing matters. Introducing a food allergen early in the day or midday is ideal—you’ll have plenty of time before putting your little one down for a nap or to bed to watch for any allergic reactions.
Start small. Introduce a small amount of an allergenic food with foods your baby likes and tolerates well (adding a ¼ teaspoon of peanut butter to cereal, or a small bite of scrambled egg served with the meal, for example), and gradually increase the amount served if you don’t observe a reaction.
Introduce one allergen at a time. Add a single common allergen at mealtime (as in don’t offer both yogurt and eggs simultaneously until you know that one allergen is tolerated; otherwise, you won’t know which food triggered the allergic reaction).
Consistent exposure is key. Continue to include allergenic foods at meal time regularly every week (ideally, at least one exposure every day), and aim to expose your baby to as many allergens as possible before their first birthday. Maintaining frequent feedings is necessary for your little one to decrease the likelihood of developing a food allergy.

Tips for Introducing the Most Common Food Allergens

When introducing major allergens, there’s no set order to follow—consistently exposing your baby to allergens is more important than which foods you introduce when. Of course, when feeding your baby any solid food (allergen or not), make sure they’re prepared with your baby’s development in mind, and avoid choking hazards, undercooked meat and fish, and any unpasteurized dairy products.

Here are some ideas for exposing your little one to the nine most common food allergens:

Introducing Milk

Whole milk yogurt
Whole milk cottage cheese
Butter (either melted in a puree, cereal, or oatmeal; spread onto a cracker, toast, or other appropriately prepared food at room temperature)
Cereals that contain “milk powder” in the ingredients list

Introducing Eggs

Very small pieces of scrambled egg
Blending scrambled egg into purees or smoothies
Mashing boiled egg with purees, breast milk, or smoothies

Introducing Fish

Small pieces or flakes of cooked salmon
Blend small amounts of cooked fish into veggie purees
Small pieces or flakes of canned light tuna, such as flapjack

Introducing Shellfish

Small pieces of steamed, sauteed, or roasted shrimp
Small pieces of crab cake (assuming other allergens, like egg and milk, have been introduced)
Clam chowder (assuming other allergens, like egg and milk, have been introduced)

Introducing Tree Nuts

Mix tree nut butter (almond, cashew, or hazelnut) with formula or breast milk
Mix tree nut butter (almond, cashew, or hazelnut) into cereal or oatmeal
Add a small amount of almond flour to purees or smoothies

Introducing Peanuts

Mixing peanut butter into cereal or oatmeal
Mixing peanut butter with formula or breast milk
Peanut butter puffs
Thinly spreading peanut butter on a cracker or toast

Introducing Wheat

Small pieces of soft cooked pasta
Small pieces of pancake or waffle (assuming other allergens, like egg and milk, have been introduced)
Wheat based first cereals

Introducing Soy

Soy yogurt
Small pieces of soft tofu on their own or blended with a puree or smoothie
Create a puree of cooked edamame and breast milk or formula

Introducing Sesame

Hummus thinned with breast milk or formula
Tahini thinned with breast milk or formula (if necessary)
Blend tahini into purees and smoothies

What Warning Signs of an Allergic Reaction Should You Look For?

When introducing new allergenic foods to your baby, it’s important to be aware of potential warning signs of a food allergy. If your little one experiences any of the following symptoms after eating a specific food, it could indicate an allergic reaction:

Skin reactions, including redness, itching, hives, and swelling beneath the skin.
Respiratory reactions, including nasal congestion, runny nose, itching, sneezing, hoarseness, cough, wheezing, and tightness in the chest.
Gastrointestinal reactions, including nausea, reflux, abdominal pain, vomiting, and diarrhea.
Eye reactions, including itchiness, redness, swelling, and tearing.
Mouth reactions, including swelling in the tongue, lips, or throat.
Cardiovascular reactions, including rapid heart beat, low blood pressure, dizziness, and fainting.

These symptoms can vary in severity, and generally, most allergic reactions are immediate (though some can take a few hours or even days to present). If you observe any symptoms, it’s essential to speak with your child’s pediatrician for guidance—they will evaluate your baby’s symptoms, review the timing of the allergen introduction, and may order further testing, if needed.

When symptoms are severe and involve organ systems, it is called anaphylaxis and can be life-threatening—signs are often respiratory, and include hoarseness, wheezing, and difficulty breathing. Seek immediate medical assistance or emergency services if you suspect your child is experiencing anaphylaxis.

What If Your Child Has an Allergic Reaction?

If your baby is experiencing mild or moderate symptoms of an allergic reaction, avoid exposing your child to the suspected allergen, and monitor the reaction (it’s smart to take notes of symptoms and pictures of any skin reactions). Reach out to your pediatrician or healthcare provider, who may suggest giving your child an antihistamine.

How Do You Know If Your Child Has Outgrown a Food Allergy?

If you believe your child has outgrown a food allergy, their pediatrician will refer you to an allergist for evaluation and testing. They’ll consider your child’s medical history, symptoms, and run tests for proper diagnosis. These are the steps involved in assessing whether your child has outgrown a food allergy:

Medical history review. The allergist will evaluate your child’s medical history, including the initial allergic reaction, any subsequent reactions, and the timeline of symptoms. Details about the severity and nature of the reaction will be important in determining the likelihood of outgrowing the allergy.
Allergy testing. The allergist may recommend specific allergy tests to evaluate your child’s allergic response to the suspected food allergen.
- A skin prick test will be performed—a small amount of the allergenic food extract is placed on the skin, and then the skin is scratched or pricked. If a welt or bump develops, it indicates a positive reaction to the allergen.
- Blood tests for specific IgE will be performed—elevated levels of these antibodies suggest an allergic response.
- Your child will do an oral food challenge under supervision—your child will be given increasing amounts of the suspected allergen in a controlled environment.
Continued monitoring. If the initial tests indicate that your child may have outgrown their allergy, the allergist may recommend a period of avoidance, followed by a reevaluation and more testing to monitor their immune response.

Outgrowing a food allergy looks different for every kid, and is impacted by the specific food allergy and the individual immune system. Some allergies, such as milk and egg allergies, are frequently outgrown, while allergies to peanuts, tree nuts, sesame, fish, and shellfish are often lifelong.

Beginning solids with your baby is equal parts exciting and stressful, and introducing allergens to your new eater can feel intimidating (and very high stakes!). Just remember, it’s a vital step to ensuring your child stays healthy and minimizing the risk for future food allergies. As always, it’s never a bad idea to reach out to your pediatrician for extra guidance and support.