Introducing Allergens to Babies: The New Guidelines

For decades, parents were told to delay introducing allergenic foods. The LEAP study in 2015 upended that guidance entirely. We now know that early introduction of peanut products — starting around four to six months, after the baby has tolerated other solid foods — reduces peanut allergy risk by up to 80% in high-risk infants.

Dr. Scott Sicherer, director of the Jaffe Food Allergy Institute at Mount Sinai, helped shape the current AAP guidance: introduce peanut-containing foods (thinned peanut butter, peanut puffs) early, around four to six months. High-risk infants (those with severe eczema or existing egg allergy) should have allergy testing before introduction, but testing is not needed for most babies.

The practical method: mix a small amount of smooth peanut butter with breast milk, formula, or a puree the baby already tolerates. Start with a tiny taste — half a teaspoon. Wait 10 minutes. If no reaction, offer the rest. Do this at home, during daytime hours, not for the first time at daycare or a restaurant.

Egg is the second major allergen to introduce early. Well-cooked scrambled egg (not runny or soft-boiled) can be offered once the baby handles basic purees. Start with a small amount — about a teaspoon — and observe. Tree nuts (almond butter, cashew butter) follow a similar timeline, thinned to an appropriate consistency.

According to a 2023 JAMA Pediatrics review, only 1.6% of infants experience a clinically significant reaction during supervised early introduction. Signs of an allergic reaction include hives (raised red welts), swelling of the face or lips, vomiting, or difficulty breathing. Mild reactions (a few hives around the mouth) are common and not necessarily an allergy — contact irritation from acidic or rough-textured foods can mimic mild allergic symptoms. Persistent or spreading hives, any breathing difficulty, or vomiting warrant immediate medical attention.

Consistency matters more than the initial introduction. The LEAP study showed that children who continued eating peanut products two to three times per week maintained their protection. A single early introduction followed by months of avoidance does not confer the same benefit. Make allergenic foods a regular part of the rotation, not a one-time experiment.