How to Introduce Allergens to Baby: Safe and Early Introduction Guide

Once your baby is ready for solids, usually around 6 months, introduce the nine common allergens early, one at a time, in age-appropriate textures. Current evidence shows that introducing allergens like peanut and egg early, rather than delaying them, may help reduce the risk of developing some food allergies. If your baby has significant eczema, an existing allergy, or a strong family history, speak to your pediatrician before you start.

Introducing allergens can feel intimidating, but the science has shifted in recent years toward earlier, confident introduction. This guide explains the nine common allergens, how to offer them safely by age and texture, what reactions look like, and when to get help. Your pediatrician should guide the plan for your individual baby.

The 9 common food allergens

A small number of foods cause most childhood food-allergic reactions. Knowing them helps you introduce each one deliberately.

The nine common allergens and baby-friendly forms

Food / hazard	Why	Safer approach
Peanut	Common, can be severe	Thin smooth peanut butter or peanut flour mixed into puree, never whole
Tree nuts (almond, cashew, walnut)	Choking and allergy risk whole	Smooth nut butters thinned, or finely ground into food
Egg	Very common in young children	Well-cooked and mashed; avoid raw or undercooked egg
Cow's milk	Common allergen	As yogurt or cheese or in cooking; not as a main drink under 12 months
Soy	Common allergen	Smooth tofu, mashed; soy in cooking
Wheat	Common allergen	Soft well-cooked pasta, bread strips, iron-fortified cereal
Fish	Common allergen	Well-cooked salmon or cod, flaked finely, all bones removed
Shellfish (crustacean)	Can be severe	Well-cooked, finely chopped; introduce as your pediatrician advises
Sesame	Increasingly recognised allergen	Smooth tahini thinned into food; avoid whole seeds early on

Introduce early, one at a time

Two principles guide safe allergen introduction.

Don't delay

For most babies, there is no benefit to waiting and possibly a downside. Introduce allergens around 6 months, once your baby can sit with support, has good head control, shows interest in food, and can move food to the back of the mouth.

One at a time

Offer a single new allergen at a time, earlier in the day so you can watch your baby afterward, and wait two to four days before introducing the next. This makes it far easier to identify the culprit if a reaction occurs. Start with a small amount, and if all is well, gradually offer more, and keep that allergen in the diet regularly once tolerated.

Age-appropriate textures

Allergens should be served in forms that are both safe from choking and easy for your baby to eat.

• Peanut and tree nuts: never whole or as a stiff spoonful. Thin smooth peanut butter with water, breast milk, formula, or yogurt, or stir peanut flour into a familiar puree.
• Egg: cook thoroughly and mash; offer scrambled or hard-boiled, never runny or raw.
• Fish: cook fully, flake finely, and check carefully for bones, salmon and cod are good first choices.
• Cow's milk: offer as plain full-fat yogurt or cheese, or use in cooking, rather than as a drink before 12 months.
• Sesame: mix smooth tahini into purees or spread thinly rather than offering whole seeds.

What an allergic reaction looks like

Most reactions are mild and appear quickly, usually within minutes to a couple of hours.

Recognising allergic reactions

Food / hazard	Why	Safer approach
Mild signs	Skin and gut response	Hives, redness, mild swelling around the mouth, an itchy rash, mild vomiting, stop the food and call your pediatrician
Severe signs (anaphylaxis)	Whole-body reaction	Trouble breathing, wheeze, swelling of tongue or throat, persistent vomiting, floppiness, pale or blue skin, call emergency services immediately

When to seek help

For mild symptoms, stop offering the food, write down exactly what happened and when, and contact your pediatrician before trying that food again. They can advise on next steps, which may include allergy testing or a referral. For any severe symptoms, treat it as an emergency immediately.

Keeping it positive

Introducing allergens is one of the most valuable things you can do for your baby, and most babies tolerate them without any trouble. Offer them alongside the foods your baby already enjoys, a little peanut butter swirled into oatmeal, mashed egg with avocado, flaked salmon, or a spoon of plain yogurt, and keep mealtimes relaxed. Once a food is tolerated, keep it in the diet regularly, since ongoing exposure helps maintain tolerance.

This guide is educational and does not replace personalised medical advice. Your pediatrician is your best partner for building an allergen-introduction plan that fits your baby's health history and your family's needs.