Allergenic foods: when and how to introduce them

For years, people believed that delaying allergenic foods would reduce the risk of allergies. Current guidance points in a different direction: once your baby is ready for solids, there is no reason to automatically delay egg, peanut, fish, milk and other allergens.

This guide is part of the starting solids path. Before beginning, check readiness signs in weaning: the first tastes and unsafe preparations in foods to avoid in the first year.

What does current research say?

Research on early introduction, especially for peanut and egg, has changed the approach: delaying without a reason does not appear to prevent allergies and, for some babies, correct and regular introduction may help tolerance.

This does not mean giving large amounts or experimenting randomly. It means introducing allergens when your baby is ready for solids, in safe forms, one at a time and with attention to symptoms.

The main food allergens

The most common allergens are:

1. cow's milk, as an ingredient or yogurt, not as the main drink before 12 months;
2. eggs, always well cooked;
3. peanuts, never whole;
4. tree nuts, never whole;
5. fish, well cooked and boneless;
6. shellfish and mollusks, well cooked;
7. wheat;
8. soy;
9. sesame.

The issue is not only allergy: some allergenic foods are also choking hazards if offered in the wrong form.

How to introduce them safely

The basic rule

Introduce one new allergen at a time, in tiny amounts, when your baby is well. Avoid first trials during fever, stomach illness, just-after vaccinations or days when you cannot observe your baby.

The first time

• choose morning or lunch, not evening;
• start with a tiny amount, such as the tip of a teaspoon;
• wait and watch before increasing;
• do not introduce two new allergens on the same day;
• if tolerated, keep offering it regularly over the following weeks.

You do not need to wait 3-5 days between every non-allergenic food if your baby is well, but for allergens it is useful to keep first trials separate so reactions are easier to interpret.

Practical examples

• Egg: well cooked, mashed into food or offered as soft strips of fully cooked omelette.
• Peanut: 100% peanut butter thinned with water, breast milk, formula or yogurt; never thick spoonfuls and never whole peanuts.
• Tree nuts: fine flour or diluted butter, never whole almonds, hazelnuts or walnuts.
• Fish: fully cooked, finely flaked and checked carefully for bones.
• Milk: plain full-fat yogurt with no added sugar or small amounts in recipes; not as the main drink before 12 months.

How to recognize an allergic reaction

Reactions often appear within minutes or a few hours, but they can vary.

Possible mild reactions

• redness around the mouth;
• localized hives;
• itching;
• slight swelling of the lips;
• isolated vomiting.

Contact your pediatrician to understand whether to stop the food, how to record the episode and whether allergy assessment is needed.

Severe reactions: call emergency services

• breathing difficulty;
• swelling of tongue, throat, face or eyes;
• voice or cry suddenly sounding different;
• marked paleness, unusual sleepiness or loss of consciousness;
• repeated vomiting with other symptoms;
• rapid worsening after food.

Children at higher risk

Talk to your pediatrician or allergist before introducing allergens if your baby has:

• moderate-to-severe eczema;
• a previously diagnosed food allergy;
• previous reactions to a food;
• specific pediatric guidance because of prematurity, growth or other conditions.

A family history of allergies is worth discussing with your pediatrician, but it does not always mean allergens must be avoided or delayed.

Common mistakes

• Delaying all allergens until after the first birthday "to be safe."
• Offering whole peanuts or whole tree nuts.
• Trying several allergens in the same meal.
• Doing the first trial in the evening, when observation is harder.
• Stopping for months a food that had been tolerated.
• Treating contact redness around the mouth as a confirmed allergy without assessment.

How to fit them into weaning

You can alternate allergens and simpler foods during the first weeks. For example: vegetable and grain first, then yogurt or well-cooked egg, then legumes, then fish, then thinned peanut butter. This is not a mandatory schedule: it should fit your baby and your family cooking.

If you need practical ideas, start from the first baby food recipes. If you use BLW, check safe forms in the Baby Led Weaning guide.

Introducing allergens gradually does not mean doing everything alone at all costs. When risk is higher or a doubt is serious, your pediatrician is part of the plan.