Introducing allergenic foods early: the ASCIA approach

6–9 months · Feeding · Reviewed 20 June 2026 · All articles

For years, parents were told to hold off on giving babies foods like peanut and egg, on the assumption that early exposure would trigger allergies. That advice has been reversed by strong evidence. The Australasian Society of Clinical Immunology and Allergy (ASCIA), the American Academy of Pediatrics (AAP), and a landmark clinical trial called LEAP now all point in the same direction: introducing allergenic foods early, once solids begin, is the safest strategy for most babies.

This guide explains what the research shows, which foods to introduce first, how to do it practically, and when you should involve a healthcare professional before starting.

What changed and why

Before 2015, guidance from many allergy and paediatric bodies recommended delaying introduction of high-risk foods such as peanut, egg, and tree nuts until a child was at least one year old, or even older. The logic seemed sensible: if a food is allergenic, avoid it until the immune system is more mature.

The problem was that allergy rates rose sharply during the same period these avoidance guidelines were in effect. Researchers began to question the assumption that avoidance was protective.

The LEAP (Learning Early About Peanut Allergy) trial, published in the New England Journal of Medicine in 2015, was the pivotal turning point. The study enrolled 640 infants aged 4 to 11 months who were at high risk for peanut allergy because they had severe eczema, egg allergy, or both. Half were randomly assigned to consume peanut products regularly from infancy; the other half avoided peanut entirely. At age 5, the group that had eaten peanut had an 81 percent lower rate of peanut allergy compared with the avoidance group. The effect held for both skin-test-positive and skin-test-negative infants.

LEAP was followed by the LEAP-On study, which showed that the protection continued even after peanut was removed from the diet for a year. The science was clear: early, regular exposure did not provoke allergy; it prevented it.

ASCIA updated its infant feeding guidelines in response to this and related evidence. The AAP followed with its own position paper in 2019, later reinforced in 2023, explicitly recommending early introduction of multiple allergens for most infants, including those at higher risk. These are no longer fringe positions; they represent mainstream clinical consensus across allergy and paediatric bodies globally.

The nine common allergens

ASCIA identifies nine foods that cause the majority of allergic reactions in infancy and early childhood:

All nine should be introduced during infancy, ideally by 12 months of age. There is no established benefit in introducing them in a specific order relative to each other, though starting with one at a time makes it easier to identify which food caused a reaction if one occurs.

Cow's milk is worth noting separately. Whole cow's milk as a main drink is not recommended before 12 months, but dairy products such as yoghurt and cheese can and should be introduced from around 6 months as part of a varied diet.

When to start

ASCIA recommends introducing allergenic foods at around 6 months of age, once your baby is developmentally ready for solids and is already accepting purees or soft foods. The upper boundary matters too: do not deliberately delay beyond 12 months. Evidence suggests the window of opportunity for tolerance induction is widest in early infancy and narrows over time.

Your baby does not need to have been on solids for any set period before starting allergens. If your baby has been tolerating non-allergenic foods for a week or two, you can begin introducing the nine allergens one by one. You do not need to wait until a paediatric check-up if your baby is otherwise well and developing normally and has no severe eczema or known prior allergy.

A common question is whether it is safe to introduce allergens if your baby is unwell. The advice is to wait until your baby has recovered from any illness, including a cold or fever, before introducing a new allergenic food. Introducing during illness can make it harder to distinguish a reaction from illness symptoms, and the immune system may respond differently when under stress.

Practical steps for first introduction

The general method recommended by ASCIA for introducing any new allergenic food follows the same pattern:

  1. Offer a small amount first. Start with about a quarter teaspoon, mixed into a food your baby already accepts if needed. For peanut, this means smooth peanut butter or peanut flour thinned to a safe consistency, never whole nuts or large pieces. For egg, well-cooked scrambled egg or hard-boiled egg mashed into puree is appropriate.
  2. Wait and watch. Keep your baby with you for 15 to 20 minutes after the first taste. Most allergic reactions to food appear within this window, though symptoms can occasionally take up to two hours. Common signs of a reaction include hives, swelling around the mouth, vomiting, or wheeze. If your baby shows no reaction, you can offer a larger amount at the same meal.
  3. Introduce one new allergen at a time. Space new allergens at least two days apart so you can clearly identify which food caused any reaction.
  4. Choose a calm moment. Introduce new allergens when you are at home, can watch your baby closely, and are not about to leave for an outing. Avoid introducing a new allergen immediately before bedtime.
  5. Keep the food in the diet. Once your baby tolerates a food, include it regularly. ASCIA recommends at least twice a week to maintain tolerance.

If your baby does have a reaction, note exactly what they ate and when symptoms appeared. Mild symptoms such as a small rash around the mouth only may be managed at home, but contact your GP or paediatrician before the next introduction. For any signs of a severe reaction such as difficulty breathing, significant swelling of the face or throat, collapse, or pale and floppy appearance, call emergency services immediately.

Eczema and family history

Eczema is the strongest risk factor for food allergy in infancy. Babies with eczema, especially moderate to severe eczema, have a higher baseline risk of developing peanut and egg allergy. This is thought to be because inflamed skin may allow food proteins to enter through the skin barrier and sensitise the immune system before the gut has a chance to build tolerance through oral exposure.

For babies with mild to moderate eczema that is well-controlled, ASCIA still recommends introducing allergenic foods at home, at around 6 months. A family history of allergy alone, meaning a parent or sibling with hay fever, asthma, or food allergy, is not a reason to delay. You can proceed with home introduction.

For babies with severe eczema that is difficult to control despite treatment, or for babies who have already had a reaction to one food, ASCIA recommends referral to a clinical immunologist or allergist before introducing the remaining allergens. In this case, introduction may be performed as a supervised oral food challenge in a clinical setting where a reaction can be managed safely.

The LEAP trial specifically studied high-risk infants and found the greatest absolute benefit in this group. That is, the babies most likely to develop peanut allergy gained the most from early peanut introduction. This is a useful reframe for parents of babies with eczema: early introduction is especially important, not something to avoid.

Maintaining tolerance over time

One of the most important and often overlooked parts of the ASCIA guidance is what happens after the first successful introduction. Many parents assume that once a food has been tried once and tolerated, the job is done. The evidence suggests otherwise.

Tolerance is an active state that requires ongoing exposure to maintain. If a food is introduced and then not offered again for several months, the immune system may lose its tolerance and a new allergy can develop. This is sometimes called "loss of tolerance" and has been observed in children who were introduced to peanut successfully but then had it removed from their diet for a prolonged period.

ASCIA recommends offering each tolerated allergen at least twice a week going forward. This does not mean a separate bowl of peanut butter every few days. Peanut butter on toast, scrambled egg at breakfast, yoghurt as a snack: regular inclusion in ordinary meals is the goal. Think of it less as a medical protocol and more as building a varied diet from the start.

Frequently asked questions

At what age should I start introducing allergenic foods?

ASCIA and the AAP both recommend introducing allergenic foods from around 6 months of age, and no later than 12 months, for most babies. The key condition is that your baby has already started solid foods and can manage the texture. There is no benefit in waiting past 6 months, and research suggests earlier introduction reduces allergy risk.

How do I introduce peanut to my baby for the first time?

Use smooth peanut butter or peanut flour mixed with expressed breastmilk, formula, or cooled boiled water to form a thin paste. Offer a small amount (about a quarter teaspoon) on a spoon. Wait at the table for 15 to 20 minutes and watch for any reaction before giving more. Never give whole peanuts or large pieces to babies under 5 years old due to choking risk.

What if my baby has eczema or a family history of allergies?

Babies with mild to moderate eczema should still be introduced to allergens at home, but do so when the eczema is well-controlled and your baby is well. Babies with severe, difficult-to-control eczema or a known egg allergy should be referred to an allergist or immunologist for a supervised introduction. A family history of allergy alone is not a reason to delay.

Do I need to keep giving allergenic foods once my baby has tolerated them?

Yes. ASCIA guidelines recommend offering the tolerated food regularly, at least twice a week, to maintain tolerance. Stopping for several months may allow a new allergy to develop. Regular inclusion in your baby's diet is the practical goal once tolerance is established.

Track your baby's solid food journey in Cubby. Log each new food, note any reactions, and keep a running record your paediatrician will appreciate at your next visit.

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