Introducing allergens safely

The advice on allergen introduction in Australia has been rewritten over the last decade. The LEAP and EAT studies — along with confirmatory Australian research — have shifted the guideline from 'delay if there's family history' to 'introduce early and regularly in all babies'. This is one of the most significant evidence-based shifts in paediatric nutrition of the past twenty years.

The current ASCIA guidelines

The Australasian Society of Clinical Immunology and Allergy (ASCIA), which issues Australia's allergy prevention guidelines, currently recommends:

• Introduce all common allergenic foods to all infants before 12 months of age, ideally starting from around 6 months (and not before 4 months).
• Continue regular exposure — at least twice a week — once introduced. Exposure needs to continue to maintain tolerance; stopping is associated with re-sensitisation.
• The recommendation applies whether or not there is family history of allergy or eczema.
• Delayed introduction (waiting until after 12 months) is not recommended and may actually increase allergy risk.

The common allergens

The foods ASCIA recommends introducing early are:

• Peanut (smooth peanut butter or peanut paste thinned with water or breast milk; never whole peanuts under 5 years — choking hazard).
• Egg (well-cooked; ASCIA guidance is cooked egg first rather than raw/runny).
• Cow's milk (small amounts in foods like yoghurt or cheese. Cow's milk as a drink is not recommended before 12 months; as an ingredient in food, it is fine).
• Wheat.
• Soy.
• Sesame (tahini, hummus).
• Fish and shellfish.
• Tree nuts (smooth nut butters, not whole nuts).

How to introduce them

One at a time, in the morning

Introduce each new allergen separately, with a few days in between if you want to be thorough. Morning introduction is preferable so that if a reaction happens, it is during waking hours when you can respond.

Start small

A quarter teaspoon of peanut butter smeared on a finger of toast; a small amount of well-cooked scrambled egg; a teaspoon of yoghurt. If there is no reaction over 10–15 minutes, increase the amount over subsequent meals.

Keep it regular

Introducing is not enough. Ongoing regular exposure — at least twice weekly — is what maintains tolerance. A child who had peanut once at 7 months and not again until 18 months may be as at-risk as a child who never had it.

What an allergic reaction looks like

Mild to moderate reactions

• Hives (urticaria) on skin, especially around the mouth or at contact points.
• Swelling of the face, lips, or eyes.
• Vomiting immediately after exposure.
• Tingling in the mouth.
• Abdominal pain, reflux symptoms worsening.

Severe (anaphylaxis) — call 000 immediately

• Difficult or noisy breathing.
• Swelling of the tongue or throat.
• Difficulty talking or hoarse voice.
• Wheeze or persistent cough.
• Persistent dizziness or collapse.
• Pale and floppy (young children).

High-risk infants

Infants with severe eczema, or existing food allergy, or both, are at higher risk of peanut allergy specifically. The old advice would have been to delay peanut. The current ASCIA advice is the opposite: these babies benefit most from early introduction, but should have their first peanut exposure in a medical setting or after consultation with a clinician. Discuss with your GP if either of the following applies:

• Severe eczema — requiring prescription treatment, or persistent despite good management.
• Existing confirmed food allergy to another food.

For these infants, allergy-testing or medically-supervised introduction may be recommended before home introduction.

Common confusions

'Eczema first, allergy later' is not a rule

Many infants with eczema do not develop food allergy. The link is a risk factor, not a prediction. The current guideline applies regardless of eczema status, though high-risk babies benefit from the earlier discussion with a clinician.

Reflux is not necessarily allergy

Reflux in babies is common and most often not allergy-driven. Cow's milk protein intolerance can present with reflux-like symptoms, but diagnosing it requires more than parental suspicion. Discuss with your GP or child health nurse if concerns persist.

Breastfeeding does not prevent food allergy

Exclusive breastfeeding is associated with many benefits but is not a reliable prevention for food allergy. Babies develop food allergies whether they are breast- or formula-fed. What matters more for allergy prevention is the introduction of allergens during the 4–12 month window.

Where to find current information

ASCIA publishes free parent information sheets on allergy prevention — allergy.org.au/patients is the authoritative source. The National Allergy Strategy (nationalallergystrategy.org.au) runs a Nip Allergies in the Bub program specifically aimed at early allergen introduction.

Do not rely on older books or advice from family members who raised children before 2015 — the guidance has fundamentally changed and their memory of the old advice (delay, avoid) is not the current recommendation.

The shift in allergen-introduction advice is one of the clearest examples of paediatric science actively changing recommendations based on new evidence. Early introduction, regular exposure, and swift response if a reaction occurs — that is the modern approach, backed by some of the best trial data in infant nutrition.