The Ultimate Guide to Introducing Allergens: Tips for New Parents

Introducing your baby to solids is exciting — but when it comes to introducing allergens, it can also feel a bit nerve-wracking. The good news? With the right timing and a little know-how, introducing allergens early can actually help reduce your baby's risk of developing food allergies.

Here’s your friendly, no-stress guide to understanding when and how to introduce allergens safely, following the guidelines from the Australian Society of Clinical Immunology and Allergy (ASCIA).

Understanding Food Allergens

What are allergens?

Allergens are substances (usually proteins) that can trigger an allergic reaction in some people. When it comes to food, the body's immune system mistakenly reacts to certain proteins as if they’re harmful, leading to symptoms that range from mild to serious.

Common allergens in infancy

According to ASCIA, the foods most likely to cause allergies in babies and young children include peanut, egg, cow’s milk (dairy), tree nuts (cashew, almond, walnut, hazelnut, pine nut, macadamia, brazil nut, pecan, pistachio), soy, wheat, fish, shellfish, crustaceans and sesame. These are often called the “common food allergens” and they’re the ones you’ll want to focus on when introducing allergens.

Timing of Allergen Introduction

When to introduce allergens to baby

One of the biggest shifts in allergy prevention has been around timing. Research now shows that introducing allergens early in the first 12 months of life -  rather than delaying them, can help reduce the risk of food allergies.

Introducing allergens at 4 months vs 6 months

Ideally, allergens should be introduced to babies around 6 months, but not before 4 months, when your baby shows signs of being ready for solids. Signs of readiness include sitting up with minimal support, good head and neck control, showing interest in food, and reaching out for food.

If your baby is developmentally ready, it’s safe to start introducing solids — including common allergens — any time from 4 to around 6 months of age. There's no benefit in delaying the introduction of these foods, and introducing them within this window may actually help reduce the risk of food allergies, particularly in babies with eczema or a family history of allergies. Waiting beyond 12 months to offer allergens may increase the chance of allergies developing. It can be helpful to let your baby get used to the idea of eating solid food for a couple of weeks when you first start solids, so both you and bub feel a bit more settled before introducing allergens.

Preparing for Allergen Introduction

Signs of food allergies in babies

Before you start offering allergenic foods, it’s helpful to know what allergic reactions might look like. Signs can include redness around the mouth or face, hives (itchy, raised welts on the skin), vomiting, swelling of the lips, eyes, or face, coughing, wheezing, or difficulty breathing. In rare but severe cases, babies may become pale, floppy, or extremely drowsy - this is anaphylaxis and requires immediate medical attention.

Allergen introduction baby schedule

There’s no strict order when it comes to introducing allergens. If there’s a family history of allergies, some research suggests starting eggs before 8 months may help reduce the risk of an egg allergy. Otherwise, it can make sense to begin with the foods your family eats most often. We do recommend only introducing one allergen per week to give plenty of time to monitor for reactions. This also gives you a few days break in between allergens, and even gives you time to take a few weeks off if needed and still get them all done by 12 months. Here’s a sample schedule starting with the more commonly eaten foods:

1. Egg
2. Peanut
3. Wheat
4. Dairy
5. Soy
6. Fish
7. Sesame
8. Almond
9. Cashew
10. Walnut
11. Pine nut
12. Macadamia
13. Pecan
14. Hazelnut
15. Brazil nut
16. Pistachio
17. Crustaceans (eg prawns)
18. Molluscs (eg scallops)

Methods for Introducing Allergens

Early allergen introduction methods

Here’s a simple approach to introducing allergens: 

1. Choose one allergen for the week.
   Stick to just one at a time so you can monitor for any reactions.

2. Day 1: Mix ¼ teaspoon of the allergen into a previously tolerated puree or food.
   Watch closely for 2 hours for any signs of a reaction.
   Day 2: If no reaction occurred on Day 1, offer ½ teaspoon mixed into a tolerated food.

3. Day 3: If no reaction again, increase to 1 teaspoon in a familiar food.

4. Ongoing: If tolerated across all 3 days, continue to offer that allergen twice per week to help maintain tolerance.

To introduce allergens, incorporate them into foods your baby is already eating. For example, mix smooth peanut butter into mashed banana, stir cooked, pureed egg into vegetable puree, add full-fat plain yoghurt to a puree, or blend tahini (sesame paste) into a vegetable mash. Our Allergen Introduction Pack makes introducing allergens easy - with 14 of the 18 common allergens finely ground into powders, ready to mix into any puree.

Introducing allergens to baby with eczema

Babies with eczema are at a higher risk of developing food allergies. If your baby has eczema (especially moderate to severe eczema), ASCIA recommends introducing allergenic foods as soon as solids are started and continuing to offering them regularly. In fact, early introduction is especially important for these little ones to help protect against their risk of developing an allergy.

It’s important to avoid rubbing food or lotions containing food oils on your baby’s skin — particularly if they have eczema as broken or inflamed skin can increase the risk of developing food allergies through skin exposure. Smearing food on the skin is not a reliable method to test for allergies and may cause irritation. You can ease into the process by first smearing a small amount of the food on the inside of your baby’s lip and waiting a few minutes before offering ¼ teaspoon to eat.

Safely incorporating allergens into meals

To keep things safe, always offer allergens when your baby is well (not sick, teething badly, or immunised that day). Introduce allergens at home - not at childcare or in a restaurant so you’re in a controlled environment. Start earlier in the day - at least 2 hours before a nap when you’ll have time to monitor for reactions. And make sure the allergenic food is well-cooked and appropriately textured to prevent choking.

Monitoring and Responding to Reactions

Signs of allergic reactions

Reactions usually happen within minutes to 2 hours. Mild to moderate signs include hives, red rash, swelling of the face, lips, or eyes, and vomiting. Severe signs (anaphylaxis) include difficulty breathing, swelling of the tongue, noisy breathing, or your baby becoming pale, floppy, or unresponsive - call 000 immediately. Severe allergic reactions are rare, but it’s important to know what to look for.

How to respond to allergic reactions in babies

If you notice mild symptoms (like hives or vomiting), stop feeding immediately and contact your GP for advice. If your baby shows severe symptoms (like trouble breathing or becoming floppy), call an ambulance immediately (000). If you have an adrenaline injector (like an EpiPen), use it if you know how. Always follow up with your doctor after any reaction, even if symptoms are mild.

Conclusion and Resources

Key takeaways for parents

Start introducing allergens around 6 months, but not before 4 months. Introduce one allergen at a time, in small amounts, and offer allergens regularly once introduced. Know the signs of allergic reactions and be prepared to act if needed. Babies with eczema benefit from early allergen introduction. Trust your instincts — and if you’re unsure, talk to your GP or paediatrician. Early introduction might feel a little scary at first — but it’s one of the most powerful things you can do to help protect your baby from developing food allergies later on.

Our Allergen Introduction e-book provides a step by step breakdown of how to introduce each allergen and what reactions to look out for.

Additional Resources for Allergen Introduction:

• ASCIA Infant Feeding and Allergy Prevention Guidelines
• How to Introduce Solid Foods for Allergy Prevention Frequently Asked Questions
• How to recognise an allergic reaction
• What to do if you think your baby is having an allergic reaction

Frequently Asked Questions

1) What’s the best age to start introducing allergens to my baby?
You can safely begin around 6 months, once your baby is showing solid-food readiness signs (sitting up, good head control, interest in food). Don’t introduce before 4 months, and aim to complete your allergen introductions by 12 months.

2) Why should I introduce allergens early?
Early, regular exposure helps “train” the immune system to tolerate these foods rather than overreact. Clinical studies (like the LEAP trial) show up to an 81% reduction in peanut allergy when peanuts are introduced between 4–11 months.

3) How do I introduce a new allergen safely?

• One at a time: Pick one allergen per week.
  
  
• Three-day ramp-up:
  
  
  • Day 1: ¼ tsp in a familiar puree
    
    
  • Day 2: ½ tsp if no reaction
    
    
  • Day 3: 1 tsp if still tolerated
    
    
• Ongoing: Offer twice weekly for maintenance once it’s cleared.
  
  

4) What are the warning signs of an allergic reaction?

• Mild–moderate: Hives, red rash, swelling around mouth or eyes, vomiting
  
  
• Severe (anaphylaxis): Difficulty breathing, tongue/throat swelling, noisy breathing, baby becoming pale or floppy – call 000 immediately.
  
  

5) What should I do if my baby shows a reaction?

• Mild symptoms: Stop the food, wipe away residue, monitor closely, and call your paediatrician if symptoms persist.
  
  
• Severe symptoms: Treat as an emergency—call 000, use an EpiPen if prescribed, and seek immediate medical care.

6) Can early allergen introduction really prevent food allergies?
Yes—most guidelines (USDA 2020–2025, ASCIA, AAP) now recommend early introduction because it can significantly lower the lifetime risk of developing allergies, especially peanuts and eggs.

7) How do I handle allergen introduction if my baby has eczema?
Babies with moderate-to-severe eczema are at higher risk. Introduce allergens (especially peanut) between 4–6 months under paediatric guidance, watching carefully for any reaction.

8) How often should I keep offering an introduced allergen?
Once your baby tolerates an allergen across three days, include it at least twice weekly to maintain tolerance—mix it into purees, yoghurts, porridge, or smoothies.

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