Introducing Allergens to Baby: A Practical Tracking Guide

Starting solid foods is exciting until someone mentions allergens. Then it gets stressful fast. Peanuts before age 1? Eggs at 6 months? What if there’s a reaction?

The good news: the science on early allergen introduction has changed significantly in the last decade. The old advice of “avoid allergens until age 3” turned out to be wrong. Current research shows that early introduction actually reduces allergy risk.

Here’s a practical guide to navigating it without losing your mind.

Why Early Introduction Matters

The landmark LEAP (Learning Early About Peanut Allergy) study, published in 2015, changed everything. Researchers followed 640 infants at high risk for peanut allergy. The group that started eating peanut products between 4-11 months had an 81% lower rate of peanut allergy by age 5 compared to the group that avoided peanuts.

Follow-up studies confirmed the pattern extends beyond peanuts. The EAT study found similar benefits for early introduction of egg and milk. The current consensus from the American Academy of Pediatrics, the Australasian Society of Clinical Immunology, and most international guidelines: introduce common allergens early, around 6 months, when baby starts solids.

Waiting doesn’t protect your baby. It may actually increase the risk.

The Top 9 Allergens

These account for about 90% of food allergies in children:

Peanuts - Most studied. Introduce as peanut butter thinned with water or breast milk (never whole peanuts, choking hazard).
Tree nuts - Almonds, cashews, walnuts, etc. Use nut butters or finely ground nuts mixed into food.
Milk - Cow’s milk mixed into food (not as a drink replacement before age 1).
Eggs - Start with well-cooked egg. Scrambled egg is a common first form.
Wheat - Baby cereal, pasta, or bread.
Soy - Tofu is an easy one. Soft, mild, easy to mash.
Fish - Flaked, well-cooked fish. Salmon and cod are common starters.
Shellfish - Well-cooked shrimp or crab, finely minced.
Sesame - Added as the 9th major allergen in 2023. Tahini mixed into purees works well.

You don’t need to introduce all 9 in a specific order. The important thing is to start them within the first year.

How to Introduce Each Allergen

The general process is the same for each one:

First Exposure

Pick a day when your baby is healthy. Not during a cold, not after vaccines, not on a day you’re rushing.
Offer a small amount of the allergen food. A quarter teaspoon is enough for the first time.
Wait and watch for 15-20 minutes. Most allergic reactions happen within this window.
If no reaction, offer a slightly larger portion.

The Waiting Period

After introducing a new allergen, feed it 2-3 times over the next week before introducing the next one. This does two things: it gives you time to spot delayed reactions, and regular exposure is what builds tolerance.

Don’t introduce two new allergens on the same day. If there’s a reaction, you need to know which food caused it.

Building Tolerance

Once introduced, keep serving the allergen regularly. Research suggests 2-3 times per week maintains tolerance. One exposure and then forgetting about it for months doesn’t help.

This is where most parents struggle. Tracking which allergens you’ve introduced, which need more exposure, and which are due for another serving is genuinely complicated when you’re managing 9 foods over several months while sleep-deprived.

Tracking Methods

Paper and Pen

A simple chart works. List the 9 allergens down one side, dates across the top. Mark each exposure. Stick it on the fridge.

Pros: Simple, visible, no technology needed. Cons: Easy to lose, hard to share with a partner or pediatrician, no room for notes about reactions.

Fridge Magnets

Some parents use a magnet board with one magnet per allergen. Green side up means introduced safely. Red means avoid. Yellow means in progress.

Pros: Visual, quick to update. Cons: Doesn’t track dates or quantities. A toddler will rearrange them.

Spreadsheet

A shared Google Sheet between parents can track dates, amounts, and reactions. More detailed but requires discipline to update.

Dedicated App

I built AllergyLog specifically for this because I went through the process myself and found notebooks and spreadsheets too easy to neglect. It tracks each allergen introduction with dates, logs symptoms with timestamps, and gives you a clear view of which allergens still need introduction or more exposure. You can also share the log with your pediatrician, which saves the “let me try to remember” conversation at checkups.

The method matters less than consistency. Pick whatever you’ll actually use.

Symptoms to Watch For

Mild Reactions (Common)

Hives or red patches around the mouth or on the body
Mild swelling of the lips or eyes
Itchy mouth or throat (baby may fuss or rub their face)
Stomach discomfort, vomiting, or loose stools

Mild reactions don’t necessarily mean your baby is allergic. Many babies get a rash around their mouth from acidic or rough foods. Contact your pediatrician, but don’t panic.

Severe Reactions (Rare but Urgent)

Difficulty breathing or wheezing
Swelling of the tongue or throat
Widespread hives that spread rapidly
Sudden vomiting or diarrhea
Becoming pale, floppy, or unresponsive

Call 911 immediately if you see any severe symptoms. Anaphylaxis is rare in infants but it’s a medical emergency.

The Tricky Part

Not all reactions are allergic. Babies spit up. They get rashes from everything. They have fussy days. The key is pattern recognition: if the same food causes the same symptom every time, that’s worth investigating with your pediatrician.

This is another reason tracking matters. “She got hives twice after egg but was fine with everything else” is much more useful to your doctor than “I think she might have reacted to something once.”

What to Do If You Suspect a Reaction

Stop the food. Don’t offer more.
Take a photo of any visible symptoms (hives, swelling, rash).
Note the time between eating and the reaction.
Note what else baby ate in the same meal.
Contact your pediatrician. They may recommend allergy testing or a supervised food challenge.
Don’t reintroduce on your own. If there was a real reaction, the next exposure should be under medical guidance.

FAQ

My baby has eczema. Should I introduce allergens differently?

Babies with moderate to severe eczema are at higher risk for food allergies, especially peanut allergy. The AAP actually recommends introducing peanut products earlier for these babies, around 4-6 months, possibly with allergy testing first. Talk to your pediatrician about timing.

Can I introduce allergens before 6 months?

For most babies, 6 months is the recommended start for solid foods. For high-risk babies (severe eczema or existing egg allergy), some guidelines suggest introducing peanut as early as 4 months with pediatric guidance. Don’t start solids early without your doctor’s input.

What if there’s a family history of allergies?

Family history increases risk but doesn’t change the recommendation. Early introduction is still preferred. Your pediatrician may want to do skin prick testing before introducing specific allergens, especially peanut.

Do I need to introduce allergens in a specific order?

No. There’s no evidence that one order is better than another. Start with whatever fits your meals. Many parents begin with egg and peanut butter because the research is strongest there, but it’s not required.

How long do I need to keep serving allergens regularly?

At least through the first year, ideally through toddlerhood. The tolerance built through regular exposure seems to be maintained as long as the food stays in the diet. Dropping a food for several months could potentially increase risk again.

This article is for informational purposes and isn’t a substitute for medical advice. Talk to your pediatrician before starting allergen introduction, especially if your baby has eczema or a family history of allergies.