How to Introduce Allergens to Your Baby: A Step-by-Step Guide

When should I introduce allergens to my baby?

Current guidelines from the American Academy of Pediatrics recommend introducing allergen-containing foods around 4–6 months of age, alongside your baby's first solid foods — and not waiting until after the first year. For most infants without significant eczema or known food allergies, you can introduce all nine major allergens as your baby shows readiness for solids.

That guidance represents a significant shift. For decades, parents were told to delay allergenic foods. The research now points in the opposite direction: earlier exposure, not avoidance, appears to help build tolerance.

If your baby has severe eczema or a known egg allergy, the approach looks a little different. Those infants may benefit from introducing peanut-containing foods as early as 4 months with guidance from their care team, and an allergist consultation may be recommended before starting.

What are the top 9 baby food allergens?

The U.S. Food and Drug Administration recognizes nine major food allergens, which together account for the vast majority of food allergic reactions. These are the foods research has focused on for early introduction:

• Peanuts — often introduced as smooth peanut butter thinned with breast milk or water
• Tree nuts — almond butter, cashew butter, or other nut butters (smooth only, not chunky)
• Milk — plain whole milk yogurt or small amounts of cheese are common first choices
• Eggs — well-cooked scrambled egg or egg yolk mixed into puree
• Wheat — wheat-containing puffs, soft cereals, or crackers moistened until soft
• Soy — plain tofu or soy-containing pureed foods
• Fish — soft, boneless, well-cooked fish like salmon or tilapia
• Shellfish — soft-cooked shrimp or crab, finely mashed
• Sesame — tahini thinned to a smooth paste (added as the 9th major allergen in 2023)

Honey is not on this list but is still avoided before 12 months due to botulism risk. Whole nuts, large chunks, and raw hard vegetables remain off the table until your child can chew safely.

How do you introduce allergens to your baby safely?

Start after your baby shows readiness for solid foods

Before introducing any allergen, your baby should show signs of solid food readiness: sitting with support, good head control, and the disappearance of the tongue-thrust reflex. Most babies reach this point between 4 and 6 months. If you're still figuring out whether your baby is ready, our guide to when babies can start solid foods walks through every sign to look for.

Introduce one allergen at a time

Introduce each new allergen on its own — not mixed with another new food. If a reaction does occur, you'll know exactly which food caused it. A common approach is to wait 2–3 days between introducing a new allergen, starting with a very small amount (about a quarter teaspoon) mixed into a food your baby already accepts. If everything looks fine over the following days, you can gradually increase the amount.

Introduce allergens earlier in the day

Offer a new allergen in the morning or at midday, when you're home and able to observe your baby for a few hours after. This is practical, not alarming — most babies tolerate allergens without any issue, and introducing earlier in the day means you won't be watching for reactions at midnight.

How often do you need to offer allergens after the first introduction?

A single successful introduction isn't enough. Research suggests offering each allergen regularly — about 2–3 times per week — to maintain the exposure and support ongoing tolerance. Once you've worked through all nine, that means rotating them into your baby's regular food rotation.

This is where tracking becomes genuinely useful. When you're managing milk or formula feeds, first purees, and multiple allergen introductions at the same time, keeping a mental log gets unwieldy. Some parents use Milk & Minutes to track feeding sessions during this window — noting new foods introduced alongside nursing or bottle feeds, so they have a clear picture of the day rather than trying to reconstruct it from memory at the pediatrician's office.

For a practical breakdown of how milk feeds and solid foods fit together at this stage, our 6-month-old feeding schedule guide has timing, quantities, and what to expect as solids become more regular.

What does the research actually say?

The shift in allergen guidance was driven largely by the Learning Early About Peanut Allergy (LEAP) study — a landmark clinical trial funded by the National Institutes of Health. It found that high-risk infants given peanut-containing foods regularly starting between 4 and 11 months had an 81% reduction in peanut allergy by age 5 compared to infants who avoided peanuts. A long-term follow-up showed those benefits extended into adolescence.

The 2024 AAP clinical guidelines built on this and similar evidence to recommend against delaying any of the top nine allergens. The goal isn't to eliminate all allergic outcomes — it's to give your baby's immune system a chance to build tolerance during the window when it appears most receptive.

The evidence is now mainstream enough that early allergen introduction is included in the 2025–2030 USDA Dietary Guidelines for Americans as a specific recommendation for infants.

Ready to take the stress out of tracking? Download Milk & Minutes free on the App Store or Google Play — track your first feed in under a minute.