When to Introduce Peanuts, Eggs, and Other Allergens to Your Baby

What changed, and why

For most of the 2000s, the standard advice was to delay common allergens — peanut until age 3, egg until age 2, cow's milk until age 1 — on the theory that a baby's immune system needed time before it could handle them safely. Food allergy rates kept climbing anyway. The Learning Early About Peanut Allergy (LEAP) trial, published in 2015, tested the opposite approach in infants already considered high-risk (babies with severe eczema, an egg allergy, or both): one group avoided peanut entirely, the other ate peanut protein regularly starting between 4 and 11 months. By age 5, the avoidance group had a peanut allergy rate several times higher than the early-introduction group — an 81% relative reduction in risk. That result reshaped guidance across the AAP, NIAID, and allergist organizations, and a 2026 Pediatrics clinical report reaffirmed the same window: introduce common allergens, including peanut, around 4 to 6 months for essentially all infants, not just those considered high-risk.

The nine major allergens, and a safe first form for each

Roughly 90% of food allergies in the US trace back to nine foods. None of them need to be avoided or saved for later — the goal is introducing each one in a form your baby can actually swallow safely at their current stage, not a specific order between them.

How to introduce a new allergen

1. Pick a time of day when you can watch your baby for a couple of hours afterward — not right before a nap, bedtime, or when you're about to leave the house.
2. Offer a small amount first, not a full portion — a half-teaspoon of thinned peanut butter mixed into puree is enough for a first try.
3. Watch for a reaction over the next 2 hours: hives, facial swelling, vomiting, repeated coughing, or trouble breathing are the signs to act on (see below).
4. If there's no reaction, you can offer a slightly larger amount at the next sitting, working toward a regular serving size over the following days.
5. Once a food is tolerated, keep it in the regular rotation — the protective effect from early introduction studies came from regular ongoing exposure, not a single successful taste.
6. Wait about 3 to 5 days before introducing the next new allergen, so if a reaction does happen, it's clear which food caused it.

Babies with severe eczema or an existing food allergy

The direction is the same for these babies — earlier introduction is still the goal — but the how differs. The NIAID-sponsored addendum guidelines that followed the LEAP study specifically recommend that infants with severe eczema, egg allergy, or both talk with their pediatrician about peanut introduction, and some of these babies benefit from an in-office peanut challenge or allergy testing (a skin-prick test or blood test) before trying it at home for the first time. This isn't a reason to delay past 4 to 6 months on your own — it's a reason to bring your pediatrician into the specific plan rather than following the general at-home steps above. If your baby has moderate or severe eczema that isn't well controlled, treating the eczema itself is often part of the same conversation, since some research has linked eczema severity to a higher likelihood of developing a food allergy through skin exposure.

Signs of a reaction, and what each one means

Most first reactions, when they happen at all, are mild — a little redness around the mouth that clears up on its own. True anaphylaxis after a first exposure is uncommon, but it's the reason the introduction steps above tell you to start small and stay nearby rather than serving a full portion of a new allergen and leaving the room.

Mistakes worth avoiding

• Waiting until after 6 months, or well into the toddler years, on the theory that later is safer — the evidence points the other way for most babies.
• Introducing a new allergen for the first time right before bed or before leaving the house, which makes it harder to notice and respond to an early reaction.
• Serving whole nuts, chunks of nut butter, or other choking-hazard forms because they seem like a faster way to "get it over with" — texture safety doesn't get a shortcut.
• Trying two new allergens on the same day, which makes it impossible to know which one caused a reaction if something happens.
• Stopping a food after one successful try instead of keeping it in the rotation — the protective effect from the research above depended on continued, regular exposure, not a single taste test.
• Skipping the pediatrician conversation for a baby with severe eczema or an existing allergy and just winging it at home the same way you would for a lower-risk baby.

Allergen introduction is really just one piece of starting solids, not a separate project — our beginner's guide to starting solid foods covers readiness signs, first-food choices, and timing in more depth, and pairs naturally with the steps above. If you're deciding between purees and letting your baby self-feed soft pieces, our baby-led weaning vs. purees comparison covers how that choice interacts with introducing new textures and allergens safely. And once you're making food at home instead of relying on store-bought purees, our guide to storing and freezing homemade baby food covers batch-cooking the allergen-containing foods above without a fridge full of half-used jars.