Introducing allergens to your baby: the complete guide
Not long ago, parents were told to delay allergens. The science flipped. Research like the LEAP study showed that introducing allergens early and keeping them in the diet can actually reduce the chance of a food allergy developing. Here's the practical version.
1. Start around 6 months, when baby is ready
Most babies are ready for solids around 6 months, when they can sit with support, hold their head steady, and show interest in food. You don't need to introduce allergens before other foods, but you don't need to save them for last either.
2. One new allergen at a time, then wait 2–3 days
Introduce a single new allergen, then wait about two to three days before the next new one. If a reaction happens, you'll know exactly which food caused it. (Yummy Yucky does this bookkeeping for you and nudges you through each watch window.)
3. Serve it in a safe form
Allergen foods have to be age-appropriate and choke-safe: smooth, thinned nut butters (never whole nuts), well-cooked egg, soft flaked fish with bones removed. Each allergen guide below covers the safe forms.
🛒 Our pick Don’t want to buy nine different foods? An early-allergen introduction kit doses the common allergens in pre-measured amounts, which some parents find simpler to work through.
4. Keep it in the diet
Introducing an allergen once isn't the finish line. Once it's tolerated, offer it regularly. That continued exposure is part of what the guidance is based on.
5. Higher-risk babies: talk to your pediatrician first
If your baby has severe eczema or an existing food allergy (especially egg), guidelines may recommend evaluation and earlier, supervised introduction of peanut. Check with your pediatrician before you start.
Signs of an allergic reaction
- Hives, redness, or swelling (lips, face, tongue)
- Vomiting or lots of drooling/coughing right after eating
- Widespread rash or worsening eczema
- Trouble breathing, wheezing, or floppiness: call emergency services immediately
Guides for each of the big 9
Frequently asked questions
At what age should I introduce allergens to my baby?
For most babies, common allergens can be introduced around 6 months, once your baby is developmentally ready for solids. Current guidance generally favors introducing allergens early rather than delaying them. Babies with severe eczema or a known food allergy should talk to a pediatrician first.
What is the 3-day wait rule?
Introduce one new allergen at a time and wait about 2–3 days before introducing the next new one. If a reaction happens, this makes it much easier to tell which food caused it.
Do I need to keep giving an allergen after the first try?
Yes, once an allergen is tolerated, current guidance is to keep it in the diet regularly rather than offering it once and stopping.
Which allergens should I introduce first?
Peanut and egg are the most studied and are often introduced early. Beyond that, you can work through the big 9 one at a time in whatever order fits your meals.
Sources
- American Academy of Pediatrics (HealthyChildren.org): starting solids & allergens
- NIAID 2017 Addendum Guidelines: prevention of peanut allergy
- LEAP Study (Learning Early About Peanut Allergy)
Track it in Yummy Yucky
Log first tries, get nudged through the 3-day allergen watch, and keep every bite in one place you can share with your pediatrician.
Start tracking for freeHow we write these: from widely published pediatric guidance (AAP, NIAID 2017 guidelines, the LEAP study), with sources cited on every page. Pending review by a pediatric professional.
This is general information, not medical advice, and has not been individually reviewed for your baby. Always talk to your pediatrician about your baby's diet, introducing allergens, and any reaction. In an emergency, contact emergency services.
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