Introducing solid foods: how to track allergens safely (8-month framework)

In this article

1. What changed: LEAP, EAT, and the new consensus
2. When to start: the 4-6 month signal window
3. The 9 priority allergens
4. The 3-day rule (and when to skip it)
5. How to introduce safely
6. Recognising a reaction
7. A tracking template that works
8. When to involve an allergist

Until 2015, the standard advice was to delay peanut introduction until 3 years old. The LEAP trial proved that wrong — early introduction reduced peanut allergy risk by 81% in high-risk infants. The current evidence-based approach is the opposite of the old one: introduce allergens early, deliberately, and with a tracking system.

What changed: LEAP, EAT, and the new consensus

Two trials reshaped solid food introduction:

• LEAP (2015): early peanut introduction in high-risk infants reduced peanut allergy at age 5 from 17% to 3%
• EAT (2016): early introduction of six allergens (peanut, egg, dairy, wheat, sesame, fish) showed similar protective effects, especially in babies with eczema

The NIAID issued updated guidelines in 2017 recommending early peanut introduction starting at 4–6 months. The AAP, EAACI (Europe), ASCIA (Australia) all converged on similar guidance: early introduction, not delayed avoidance, prevents allergy.

When to start: the 4-6 month signal window

Most babies are developmentally ready for first foods at 4–6 months. Signs:

• Sits with minimal support
• Has good head control
• Reaches for and mouths food
• Has lost the tongue-thrust reflex (food no longer pushed out)
• Shows interest in family meals

Starting earlier than 4 months: gut still too immature, choking risk, milk displacement risk. Starting later than 6 months: increased allergy risk, possible iron deficiency, missed developmental window.

“Introduce allergens early, deliberately, and with a tracking system.”

The 9 priority allergens

The top allergens responsible for most childhood food allergies:

Allergen	Form for infants	Earliest intro
Peanut	Thinned peanut butter, peanut puffs softened	4–6 months
Egg	Hard-cooked yolk or scrambled, well-cooked	6 months
Dairy	Cooked dairy in food (yogurt OK from 6 months; cow's milk as drink from 12)	6 months
Wheat	Cereal, soft bread crusts	6 months
Soy	Tofu, soy-based purees	6 months
Sesame	Tahini, thinned	6 months
Tree nuts	Smooth nut butters, never whole	6 months
Fish	Flaked cooked fish	6 months
Shellfish	Cooked, finely flaked	9–12 months

The goal: introduce each, in age-appropriate form, before the first birthday.

The 3-day rule (and when to skip it)

The traditional advice: introduce one new food at a time, wait 3 days before adding another, so reactions can be attributed correctly. This still applies — with a nuance.

For allergens specifically: introduce, wait 3 days, then continue offering 2–3 times a week. One exposure isn't enough; sustained exposure is what builds tolerance per EAT trial data.

For non-allergen foods (most vegetables, fruits, grains), you can introduce more freely. Save the 3-day spacing for the priority allergens above.

How to introduce safely

At home, not at daycare. Daycares can't always recognise or respond to a reaction; first exposure should be where you can act.

Earlier in the day, not before bed. Most reactions occur within 30 minutes to 2 hours. Mid-morning works well.

On a day baby is well. Skip introduction days when baby has a cold, fever, or runny nose — symptoms can be confused with reactions.

Start with a small amount. A pea-sized amount on day one. Double on day two. Triple on day three.

Watch the timeline. Most reactions are within 2 hours. Severe reactions (anaphylaxis) are within 30 minutes.

Recognising a reaction

Mild (most common):

• Rash around the mouth or on the body
• Hives
• Mild swelling of lips
• Mild vomiting (single episode)
• Loose stools

Mild reactions: stop offering that food, photograph the rash, call your paediatrician for next steps.

Severe (rare but emergency):

• Swelling of tongue, throat, or airway
• Difficulty breathing, wheezing, or coughing
• Pale, floppy, or unresponsive
• Persistent vomiting
• Multiple body systems affected

Severe reaction: call emergency services immediately. Don't wait.

A tracking template that works

For each new food, log:

• Date introduced
• Form (e.g., 'thinned peanut butter on toast strip')
• Amount (pea-sized / teaspoon / tablespoon)
• Time of day
• Any reaction (none / mild + description / severe + response)
• Days continued (target: 2–3 times per week for allergens)

The weekly view should answer one question: 'Has this baby been exposed to all 9 priority allergens in the past month?' By month 9, the answer should be yes for 7–8 of them.

When to involve an allergist

Talk to your paediatrician about an allergist referral before starting solids if:

• Your baby has moderate-to-severe eczema
• Your baby has an existing egg allergy
• A sibling has multiple food allergies
• There's a family history of severe allergies

For these higher-risk babies, allergists may recommend in-office peanut introduction or specific testing first. This isn't delay — it's evidence-based caution.