The Top 9 Allergens: A Parent's Complete Introduction Guide

Key Takeaways

Nine foods account for approximately 90 percent of all food allergies in children: milk, eggs, peanuts, tree nuts, soy, wheat, fish, shellfish, and sesame.
Current evidence strongly supports early introduction of allergens (starting around 4-6 months) rather than delaying them.
Introduce one new allergen at a time, with 2-3 days between each new allergen to identify the source of any reaction.
After successful introduction, maintain regular exposure – at least 2-3 times per week – to sustain tolerance.
Most allergic reactions in infants are mild, but knowing the signs of anaphylaxis and having a plan is essential.

Why Early Allergen Introduction Matters

If you became a parent before 2015, your pediatrician likely told you to delay introducing common allergens until your child was 1, 2, or even 3 years old. That advice has since been overturned. A landmark body of research – most notably the LEAP study for peanuts and the EAT study for multiple allergens – demonstrated that early introduction reduces allergy risk rather than increasing it.

The updated guidelines from the American Academy of Pediatrics (AAP) and the National Institute of Allergy and Infectious Diseases (NIAID) now recommend introducing allergenic foods early in the complementary feeding period, alongside other first foods. This represents one of the most significant reversals in pediatric nutrition guidance in decades.

Understanding which foods are major allergens, how to introduce them safely, and what to watch for empowers you to approach this stage with confidence rather than anxiety.

The Nine Major Allergens

The Food Allergen Labeling and Consumer Protection Act (FALCPA) identifies nine major allergens that must be declared on food labels in the United States. As of January 2023, sesame was added to the list, bringing the total from eight to nine.

1. Cow’s Milk

Prevalence: The most common food allergy in infants and young children, affecting approximately 2-3 percent of children under 1 year. Most children outgrow it by age 5.

Introduction: Cow’s milk protein can be introduced through yogurt, cheese, or milk cooked into foods starting around 6 months. Note that whole cow’s milk as a beverage is not recommended until 12 months – this is a nutrition guideline, not an allergy guideline. The proteins are the same whether the milk is in yogurt or a cup; it is the nutritional displacement of breast milk or formula that concerns pediatricians.

How to serve: Start with a small amount of plain, full-fat yogurt (about 1 teaspoon). Yogurt is often well-tolerated because the fermentation process partially breaks down the milk proteins. Soft cheese (like ricotta) is another early option.

2. Eggs

Prevalence: Affects about 1-2 percent of children. Most outgrow it by age 5.

Introduction: Introduce well-cooked egg (both white and yolk) starting around 6 months. Raw or undercooked egg should not be given to babies or young children due to Salmonella risk, separate from allergy concerns.

How to serve: Scramble an egg thoroughly and offer small, soft pieces. For younger babies, you can mix a well-cooked egg into a puree. Start with a small amount – about 1 teaspoon of scrambled egg.

Note: Some children are allergic to egg white protein but tolerate egg baked into foods (like muffins or bread). This is because heat denatures certain proteins. However, for initial introduction, offer recognizably eggy food so you can identify a reaction clearly.

3. Peanuts

Prevalence: Affects about 1-2 percent of children. Unlike milk and egg, peanut allergy is less commonly outgrown – only about 20 percent of children with peanut allergy resolve it by school age.

Introduction: Introduce peanut protein between 4 and 11 months. High-risk infants (severe eczema or egg allergy) should see an allergist first.

How to serve: Thin smooth peanut butter with water or breast milk to a yogurt-like consistency. Alternatively, mix peanut butter powder into purees or offer peanut puff snacks. Never offer whole peanuts (choking hazard until age 4).

4. Tree Nuts

Prevalence: Tree nut allergies affect about 1 percent of children and are among the most common causes of fatal anaphylaxis. The most common tree nut allergies are to cashew, walnut, and almond.

Introduction: Introduce tree nuts around 6 months, one type at a time. Being allergic to one tree nut does not necessarily mean allergy to all tree nuts, but cross-reactivity is common (especially between cashew and pistachio, and between walnut and pecan).

How to serve: Thin almond butter, cashew butter, or other nut butters with water or breast milk. Finely ground nut meal can be mixed into oatmeal, yogurt, or purees. Never offer whole or chopped nuts.

5. Soy

Prevalence: Affects about 0.4 percent of children. Most outgrow it by age 10.

Introduction: Introduce soy around 6 months. Soy is present in many foods, so early introduction often happens incidentally.

How to serve: Offer soft, cubed tofu (silken tofu is easiest for young babies – it can be mashed or offered as slippery cubes). Edamame, if shelled and mashed, is another option for older babies. Soy yogurt works well too.

6. Wheat

Prevalence: Wheat allergy affects about 0.4 percent of children. It is distinct from celiac disease (an autoimmune condition triggered by gluten) and from non-celiac gluten sensitivity.

Introduction: Introduce wheat around 6 months through soft, cooked pasta, infant cereal, or soft bread.

How to serve: Cook thin pasta (like orzo or small shells) until very soft. Offer small pieces of soft bread or toast strips soaked in breast milk or formula. Wheat-based infant cereal mixed to a thin consistency is another easy option.

7. Fish (Finned Fish)

Prevalence: Affects about 0.1 percent of children, but prevalence increases with age and fish allergy is often lifelong.

Introduction: Introduce well-cooked fish around 6 months. Fish is an excellent source of omega-3 fatty acids and protein.

How to serve: Offer flaked, well-cooked fish (like salmon, cod, or tilapia) with all bones carefully removed. Mash or puree for younger babies. For older babies, soft flakes work well. Choose low-mercury species: salmon, tilapia, cod, pollock, and catfish are good options. Avoid high-mercury fish (king mackerel, swordfish, shark, tilefish, bigeye tuna).

8. Shellfish (Crustaceans and Mollusks)

Prevalence: Affects about 1-2 percent of the population, but is more common in adults than children. Shellfish allergy is rarely outgrown.

Introduction: Introduce well-cooked shellfish around 6 months. Shrimp and crab are common first introductions.

How to serve: Finely chop or shred well-cooked shrimp, crab, or lobster. For young babies, mash or puree into a smooth consistency. Ensure all shell fragments are removed. Avoid raw or undercooked shellfish for all children.

9. Sesame

Prevalence: Sesame allergy affects an estimated 0.2 percent of children in the United States and appears to be increasing. It was added to the list of major allergens requiring label disclosure in 2023.

Introduction: Introduce sesame around 6 months.

How to serve: Thin tahini (sesame seed paste) with water or breast milk and mix into purees or oatmeal. Tahini is the easiest and safest form of sesame for babies. You can also offer hummus, which typically contains tahini. Avoid whole sesame seeds for young babies, as they can be difficult to swallow.

Building an Introduction Schedule

Introducing nine allergens sounds daunting, but it is manageable with a simple system. Here is a sample 6-week schedule that covers all nine, assuming you start around 6 months:

Week 1: Cow’s milk (yogurt) – offer Monday, check through Wednesday.

Week 2: Egg (scrambled) – offer Monday, check through Wednesday. Continue offering yogurt 2-3 times during the week.

Week 3: Peanut (thinned peanut butter) – offer Monday, check through Wednesday. Continue egg and yogurt.

Week 4: Tree nut (thinned almond butter) – offer Monday, check through Wednesday. Continue peanut, egg, and yogurt in rotation.

Week 5: Soy (tofu) and wheat (soft pasta) – by now you have a sense of your baby’s tolerance pattern. You can introduce two in one week (not on the same day) if you are comfortable.

Week 6: Fish (flaked salmon), sesame (tahini), and shellfish (minced shrimp) – again, not on the same day.

After all allergens are introduced, the priority shifts to regular exposure. This is often the harder part – maintaining consistent inclusion of all nine allergens in the weekly rotation.

Recognizing Allergic Reactions

Mild Reactions

Hives (red, raised welts) around the mouth, face, or body
Redness or mild swelling around the mouth
Runny nose or sneezing
Itchiness
One or two episodes of vomiting
Mild diarrhea

A mild reaction warrants a call to your pediatrician but typically does not require emergency care. Your doctor may recommend continuing the food, pausing it, or referring to an allergist.

Severe Reactions (Anaphylaxis)

Widespread hives or flushing
Swelling of the tongue, lips, or throat
Difficulty breathing, wheezing, repetitive coughing
Vomiting combined with other symptoms
Pale or bluish skin
Loss of consciousness
Limpness or unresponsiveness

Anaphylaxis is a medical emergency. Call 911 immediately. If prescribed, administer epinephrine (EpiPen Jr). Do not wait to see if symptoms improve on their own.

The Difference Between Allergy and Intolerance

Food intolerance (like lactose intolerance) involves the digestive system and causes symptoms like gas, bloating, and diarrhea. Food allergy involves the immune system and can cause hives, swelling, and anaphylaxis. The introduction process described here is focused on identifying true allergies, which are immune-mediated.

What If Your Baby Has a Reaction?

If your baby has a confirmed allergic reaction to a food:

Stop offering that food and contact your pediatrician.
Get a referral to a pediatric allergist for testing and management.
Learn to read labels for that specific allergen. The nine major allergens must be clearly identified on U.S. food labels by law.
Continue introducing other allergens unless your allergist advises otherwise. Being allergic to one food does not mean avoiding all allergens.
Ask about oral immunotherapy (OIT) if appropriate. For some allergies (particularly peanut), OIT – gradually increasing exposure under medical supervision – may be an option.

What TinyPlate Does Differently

TinyPlate builds allergen introduction directly into your child’s meal plan. Rather than managing a separate allergen calendar, the app tracks which allergens have been introduced, which are pending, and ensures regular exposure to previously tolerated allergens. If your child has a confirmed allergy, you can flag it and the app will exclude that allergen from all future meal suggestions.

The app also accounts for the interaction between allergen introduction and overall meal planning – making sure your baby is still getting variety, balanced nutrition, and age-appropriate textures while working through the allergen checklist.

Download TinyPlate free on the App Store

Sources

Togias, A., et al. “Addendum Guidelines for the Prevention of Peanut Allergy in the United States.” NIAID, 2017.
Du Toit, G., et al. “Randomized Trial of Peanut Consumption in Infants at Risk for Peanut Allergy” (LEAP Study). NEJM, 2015.
Perkin, M.R., et al. “Randomized Trial of Introduction of Allergenic Foods in Breast-Fed Infants” (EAT Study). NEJM, 2016.
American Academy of Pediatrics. “Food Allergies in Children.” HealthyChildren.org.
U.S. Food and Drug Administration. “Food Allergies: What You Need to Know.” FDA.gov, updated 2023.
FARE (Food Allergy Research and Education). “About Food Allergies.” FoodAllergy.org.
Sicherer, S.H., and Sampson, H.A. “Food Allergy: A Review and Update on Epidemiology, Pathogenesis, Diagnosis, Prevention, and Management.” JACI, 2018.