Introducing allergens to your baby is one of the most stressful parts of starting solids — especially for USA moms worried about peanut allergies. The old advice was to wait until age 1, 2, or even 3 to introduce peanuts, eggs, and shellfish. But the latest research from the American Academy of Pediatrics (AAP) shows the opposite: early introduction between 4-12 months can actually HELP reduce allergy risk.
In this guide, we’ll break down the exact timeline for when to introduce the top 9 allergens by age, how to do it safely at home, what warning signs to watch for, and include our free printable allergen timeline chart with babyfoodbyage.com logo for your fridge.
Important: This is educational information only and not medical advice. Always consult your pediatrician before starting allergens, especially if your baby has severe eczema or a family history of food allergies.
Why Early Introduction Matters (200 words)
A landmark study called the LEAP study found that babies at high risk for peanut allergy who ate peanuts early (between 4-11 months) had an 81% lower risk of developing peanut allergy by age 5 compared to babies who avoided peanuts.
This changed everything. Now the AAP and CDC recommend:
Start solids around 6 months when baby shows readiness signs: sitting with support, good head control, showing interest in food, opening mouth for spoon.
Don’t delay allergens. Introduce them in the first year.
Once you introduce an allergen and baby tolerates it, keep offering it regularly 2-3 times per week to maintain tolerance.
The top 9 allergens account for 90% of food allergies in the USA. They are: peanut, egg, dairy (milk), wheat, soy, fish, shellfish, tree nuts (almond, cashew, walnut), and sesame. Sesame was added as the 9th major allergen in the US in 2023.
Our chart organizes them by easiest and safest to start with by age.
The Timeline by Age
4-6 MONTHS: Start Here – Peanut, Egg, Dairy
These three are the most researched for early introduction and easiest to prepare as soft purees.
1. Peanut: Use smooth peanut butter thinned with breastmilk, formula, or warm water until it’s a thin puree. Never give whole peanuts or chunky peanut butter — choking hazard. Start with 1/4 teaspoon mixed into oatmeal or yogurt. You can also use peanut powder. Offer in the morning so you can watch for reaction all day.
2. Egg: Well-cooked scrambled egg, finely mashed, or hard-boiled egg yolk mashed with water. Both egg white and yolk can cause allergy, but you can introduce whole well-cooked egg. Many pediatricians say start with yolk but current guidance allows whole egg. Again start with 1-2 teaspoons.
3. Dairy: Plain, full-fat, pasteurized yogurt or soft cheese like ricotta. No cow’s milk as a drink before age 1, but yogurt and cheese are fine. Dairy in yogurt form is lower allergy risk and has probiotics.
6-9 MONTHS: Next Wave – Wheat, Soy, Fish
Baby is now eating more textures, better head control, trying mashed and soft lumps.
4. Wheat: Soft cooked pasta, infant wheat cereal, or soft bread strips toasted and cut into thin strips for baby-led weaning. Wheat is often already introduced via cereal. Watch for vomiting, rash, or persistent fussiness.
5. Soy: Tofu (soft, mashed or small soft cubes for finger food), or soft-cooked edamame mashed. Tofu is a great protein for babies and easy to prepare.
6. Fish: Low-mercury, boneless, fully cooked flaked fish like salmon or cod. Salmon is ideal because it’s high in DHA for brain development. Make sure no bones. Start with 1-2 tablespoons flaked finely.
9-12 MONTHS: Last Three – Shellfish, Tree Nuts, Sesame
These are often introduced later because they are higher choking risks or more potent allergens, but still before age 1.
7. Shellfish: Cooked shrimp or crab, finely chopped, fully cooked. Shrimp is low-mercury and high protein. Chop very finely and mix into puree or serve as tiny soft pieces. This is often a cultural food — introduce if it’s in your family diet.
8. Tree Nuts: Almond or cashew butter, very thinly spread and diluted (same method as peanut butter). Never whole nuts before age 4-5 due to choking. Thin nut butter into oatmeal. Some families use small amount of finely ground nuts mixed into foods.
9. Sesame: Tahini (sesame paste) thinned with water, or smooth hummus (contains tahini). Sesame is now a top allergen and is in many foods. Hummus is an easy way to introduce.
How to Introduce Safely – The 4 Rules
One at a time, 3-5 day wait: Introduce only one new allergen at a time and wait 3-5 days before adding another. This way if there is a reaction, you know which food caused it. Some pediatricians now say 2-3 days is enough.
Daytime, not bedtime: Always introduce new allergens in the morning or at lunch, never before bed. You need to watch for 2+ hours for immediate reactions, and some delayed reactions can happen hours later.
Start tiny: Start with ∼1-2 teaspoons of the new allergen mixed into a familiar food your baby already tolerates (like oatmeal or sweet potato). If no reaction after 2 hours, you can offer a bit more next time.
Keep offering: Once tolerated, keep offering that allergen regularly 2-3 times per week. Tolerance is not one and done — you need to maintain it.
Always have children’s antihistamine available and know where your nearest ER is, but do NOT give medicine before introducing as it can mask a reaction.
Warning Signs – When to Seek Help
Most allergic reactions happen within minutes to 2 hours. Call 911 if severe.
Mild to moderate signs:
Rash, hives, or redness around mouth, face, or skin
Mild swelling of lips or face
Vomiting, diarrhea, or persistent fussiness/crying after eating
Runny nose or sneezing
Severe signs (Anaphylaxis) – CALL 911:
Swelling of lips, tongue, or throat
Wheezing, coughing, trouble breathing, or hoarseness
Pale skin, lethargy, or collapse
Vomiting with other symptoms
If your baby has severe eczema or known egg allergy, talk to your allergist first — they may want to do testing or supervised introduction in office for peanut.