Allergen Introduction Timing Guide (2026): The Updated AAP Approach

The advice on when to introduce allergens has changed substantially over the past 15 years. The old recommendation (delay peanuts and other common allergens until age 2 or 3) was reversed in 2017 when the NIAID published the LEAP trial findings, showing that early peanut introduction in high-risk infants reduced peanut allergy rates by roughly 80 percent. Subsequent research has extended that logic to most major allergens. In 2026, the standard approach is to introduce common allergens between 4 and 6 months (or whenever solids start) and keep them in the diet regularly thereafter. This guide walks through what each allergen requires, what to watch for, and how to do it safely.

A note before specifics: every baby’s situation is different. Babies with severe eczema, a known egg allergy, or a strong family history of food allergies should be evaluated by an allergist before introducing peanut or other common allergens. Consult your pediatrician.

The big nine allergens to know

The FDA added sesame to the major allergen list in 2023, making it the 9th designated allergen alongside the original 8:

1. Peanut
2. Tree nuts (walnut, cashew, almond, pecan, pistachio, hazelnut, Brazil nut, macadamia)
3. Cow’s milk
4. Egg
5. Wheat
6. Soy
7. Fish (cod, salmon, tuna, etc.)
8. Shellfish (shrimp, lobster, crab, scallops)
9. Sesame

Together these cause over 90 percent of food allergies in US children. Other foods can cause allergic reactions but at much lower population frequency.

The general approach

The current AAP and NIAID approach for most babies:

1. Start solids around 6 months (or 4 to 6 months in some situations under pediatrician guidance).
2. Introduce one new food at a time, including allergens.
3. Wait 2 to 4 days before introducing the next new food to watch for reactions.
4. Once introduced and tolerated, keep allergens in the diet regularly (1 to 3 times a week minimum). Brief gaps are fine but long absences can let tolerance fade in some cases.
5. Avoid introducing new foods just before bed or far from home in case a reaction occurs.

The “introduce and maintain” principle is the part many parents miss. Introducing peanut once at month 6 and then not again for 8 months does not give the immune system the consistent exposure that builds tolerance.

Peanut, the highest-priority introduction

Peanut allergy is the most studied and most clearly preventable in early introduction. The protocol:

• Use thinned peanut butter (mix 1 to 2 teaspoons with hot water until pourable, then cool) or a baby-safe peanut puff product (Bamba is the most widely used).
• Offer 1 to 2 grams of peanut protein per serving (roughly 1 teaspoon of peanut butter or about 9 to 10 Bamba puffs).
• Start with a small amount on the tip of the spoon. Wait 10 minutes. If no reaction, give the rest.
• Maintain 2 grams of peanut protein at least 2 to 3 times a week for at least the first year.

Do not give whole peanuts or thick globs of peanut butter, which are choking hazards under age 4. The goal is the protein, delivered safely.

For babies with severe eczema or known egg allergy, the NIAID recommends allergist evaluation, possibly including a skin prick test or specific IgE blood test, before peanut introduction. Consult your pediatrician.

Egg, often the second introduction

Egg is the second-most-common food allergy in babies and follows similar early-introduction logic. Options:

• Cooked egg, fully scrambled, well-cooked. A piece of hard-boiled egg yolk crumbled onto soft food.
• Whole egg (white and yolk) is the standard introduction.
• Start small, wait 10 minutes, then a fuller portion.
• Maintain regular exposure: 2 to 3 times a week of cooked egg.

Avoid raw egg or undercooked egg until age 2 or older. Some babies tolerate baked egg (in muffins, pancakes) before they tolerate whole cooked egg; this is a known step in egg allergy management but should be guided by an allergist if a reaction has occurred.

Cow’s milk, dairy products

Whole cow’s milk as a drink is not recommended until 12 months. But yogurt, cheese, and butter are appropriate from 6 months onward and serve as dairy allergen introduction.

• Plain whole-milk yogurt (Greek or regular) is a useful early dairy.
• Mild cheese (mozzarella, cheddar) shredded or thin-sliced.
• Cooked dairy in foods (mac and cheese, scrambled egg with cheese).

Babies with confirmed cow’s milk protein allergy may need a hypoallergenic formula or extensively hydrolyzed formula. Consult your pediatrician.

Wheat, soy, sesame

These three are often grouped because they appear in many foods that babies already eat.

• Wheat: Iron-fortified wheat cereal, bread crusts, well-cooked pasta cut small. Introduce by 6 to 8 months.
• Soy: Tofu cubes, edamame mashed (skins removed), soy yogurt. Soy formula counts as soy exposure.
• Sesame: Thinned tahini stirred into yogurt or oatmeal, sesame seed crackers ground or crushed.

Sesame became a designated US allergen in 2023, which is why packaged foods now list it as a top allergen. The introduction approach is the same as peanut: small amount, watch, then maintain.

Tree nuts, fish, shellfish

These three are often delayed because they appear less often in typical baby foods.

• Tree nuts: Same delivery as peanut. Thinned nut butters (almond, cashew, walnut) or finely ground nuts mixed into oatmeal. Introduce one tree nut at a time.
• Fish: Flaked cooked salmon, cod, or tuna (limit tuna to 1 serving a week due to mercury, per FDA). Watch for bones.
• Shellfish: Shrimp cut very small, well-cooked. The most common shellfish allergy emerges in older children, but early introduction follows the same logic.

For fish during pregnancy and infancy, the FDA “best choices” list (salmon, cod, tilapia, shrimp) is safe at 2 to 3 servings per week. Avoid high-mercury fish (king mackerel, marlin, swordfish, shark, bigeye tuna).

What an allergic reaction looks like

Mild to moderate reactions (most common):

• Hives or red blotches on the skin
• Redness or swelling around the mouth
• Vomiting once or twice
• Mild swelling of the lips or face
• A few coughs or sneezes

Severe reactions (medical emergency):

• Difficulty breathing, wheezing, or noisy breathing
• Tongue or throat swelling
• Repeated vomiting
• Drowsiness, lethargy, or limpness
• Pale or bluish skin
• Loss of consciousness

For severe reactions, call 911 immediately. Do not wait. Have Benadryl (diphenhydramine) on hand if your pediatrician recommends it; for severe reactions, epinephrine is the treatment, and it requires an EpiPen or similar device.

A practical introduction schedule

A common pattern in the first 8 weeks of solids:

• Week 1: avocado, oatmeal, banana (low-allergen, easy first foods)
• Week 2: sweet potato, peas, peanut butter (thinned, small amount, watch)
• Week 3: maintain peanut, add scrambled egg
• Week 4: maintain peanut and egg, add yogurt or cheese
• Week 5: add wheat (iron-fortified wheat cereal or pasta)
• Week 6: add soy (tofu)
• Week 7: add sesame (thinned tahini)
• Week 8: add fish (cooked salmon or cod)

Continue maintenance exposure to each allergen 1 to 3 times a week. Tree nuts and shellfish can be staggered in around weeks 9 to 12.

For the broader context, see our baby-led weaning vs purees comparison and high chair styles comparison.

Frequently asked questions