Introducing Allergens to Baby: When and How

The short answer

In Canada, the foods that most often cause allergies, like peanut and egg, are recommended around 6 months, alongside other foods, once your baby shows they are ready to eat. Not before 4 months, and not later “just to be safe”: the Canadian Paediatric Society (CPS) and Québec’s public health institute (INSPQ) both say that delaying these foods does not prevent allergies. Offer one new allergen at a time, watch your baby, and if it is tolerated, keep it in their diet a few times a week.

This article sums up that guidance and links to the official pages at the end. It does not replace your doctor’s advice, especially if your baby has already had a reaction.

Which foods are “priority allergens”?

Two lists are often quoted, and they serve different purposes.

The INSPQ list, for feeding your baby. The guide From Tiny Tot to Toddler names the foods most likely to cause allergies in children: eggs, peanuts, tree nuts, fish and seafood, and cow’s milk protein.

Health Canada’s list, for food labels. Health Canada names “priority allergens” that must appear on food labels: eggs, milk, mustard, peanuts, crustaceans and molluscs, fish, sesame seeds, soy, tree nuts, wheat and triticale, plus sulphites. It is a labelling list, not an introduction schedule, but it makes a handy checklist: leave out sulphites (an additive, not a food to introduce) and you have ten foods to bring in over time.

When to start?

First foods come around 6 months, when your baby can hold their head up, is curious about what you eat and can keep food in their mouth. The INSPQ suggests starting with iron-rich foods and bringing in allergens at the same time as other foods, without putting them off.

For babies at higher risk, the CPS adds a detail. A baby is at higher risk if they have eczema, or if a parent or sibling has an allergic condition. The CPS recommends offering these babies foods like cooked egg and peanut at home around 6 months, but not before 4 months. It does not recommend allergy testing before introducing a food, and notes that a severe reaction on the very first try is extremely rare. If your baby has significant eczema or has reacted to a food before, talk to your doctor before you start.

Other points the sources agree on:

Breastfeeding can continue while starting solids. Changing the mother’s diet to prevent allergies is not recommended.
Cow’s milk as a drink waits until 9 to 12 months, per the INSPQ, even though dairy foods like yogurt and cheese can come earlier.

How fast?

Here, Canadian sources don’t all say the same thing:

the INSPQ and the CPS 2021 position statement accept introducing new foods, allergens included, on consecutive days;
the CPS Caring for Kids handout suggests one new allergen a day, then a two-day wait before the next.

The common ground: only one new allergen at a time, then watch your baby. Offering a new allergen in the morning or at lunch, rather than right before bedtime, leaves time to keep an eye on them. If two new foods arrive the same day and there is a reaction, you won’t know which one caused it.

Once a food is well tolerated, what matters is to keep offering it regularly, a few times a week, in age-appropriate amounts. An allergen tried once and then forgotten for months doesn’t count for much.

In what form?

Texture matters as much as timing. Whole peanuts, tree nuts and seeds are a choking hazard until age 4, according to the INSPQ. A few ways to offer common allergens, based on CPS handouts:

Peanut: smooth peanut butter, thinned with a little water, breast milk or a purée your baby already knows. For an older baby, spread thinly on a toast crust. Never a spoonful of thick, sticky peanut butter.
Egg: well cooked, mashed or in small soft pieces.
Fish: cooked, boneless, flaked.
Tree nuts: as a smooth nut butter or finely ground into a purée, never whole.
Wheat, soy, sesame: in foods already suited to babies (infant cereal, tofu, smooth tahini thinned down).

The INSPQ also reminds parents to cut grapes into quarters and grate raw carrots and celery, for the same reason.

Signs of a reaction, and what to do

Most babies tolerate these foods very well. It still helps to know what a reaction looks like. The Caring for Kids handout lists, among others, hives, an itchy mouth, vomiting, diarrhea or cramps, swelling of the face or tongue, and trouble breathing. A serious reaction usually happens within minutes to 2 hours of eating. The INSPQ adds that some delayed reactions (diarrhea, blood in the stool, marked irritability) can show up a few days later.

In Québec, the organization Allergies Québec also runs an information line for families: 1-800-990-2575.

What to write down while starting solids

Over a few months you offer dozens of foods, and several people feed your baby: daycare, grandparents, the sitter. A few simple notes save a lot of “did we already give him fish?”:

the food and the date of the first try, especially for allergens;
how it went: well tolerated, or what you noticed and how long after;
which allergens you have offered, and which are left;
how often: a tolerated allergen you haven’t offered in a while is a good reminder.

If a reaction does happen, these notes are exactly what the doctor will ask for: what, how much, what time, and what happened next.

In short

Around 6 months, alongside other foods; not before 4 months; no “preventive” delay.
One new allergen at a time, then watch; after that, a few times a week.
Safe textures: no whole peanuts or tree nuts before age 4.
Serious signs: 911. When in doubt: Info-Santé 811 or your doctor.

For the earlier months, see our article on the newborn feeding schedule, and Naître et grandir for first-meal ideas.

Frequently asked questions

At what age should I introduce allergens to my baby?

Around 6 months, alongside other foods, when your baby shows signs of being ready. The Canadian Paediatric Society says not before 4 months, and that waiting longer to prevent allergies is not recommended.

Should I wait a few days between two allergens?

Canadian sources differ: some suggest waiting two days, others, like Québec’s INSPQ, accept consecutive days. What they agree on: one new allergen at a time, then watch your baby.

How do I give peanut butter to a baby?

Never whole peanuts, which are a choking hazard until age 4. The Canadian Paediatric Society suggests smooth peanut butter thinned with water, breast milk or a purée your baby already eats, or spread thinly on toast for an older baby.

Which allergy signs mean calling 911?

According to the INSPQ: red patches on the skin along with a sudden change in how the child is doing, swollen lips or tongue, trouble breathing, or sudden vomiting. Call 911 right away.

Once an allergen is tolerated, should I keep offering it?

Yes. The INSPQ and the Canadian Paediatric Society recommend keeping it in your baby’s diet a few times a week, in age-appropriate amounts.

This article is for information; it does not replace advice from a health professional. In Québec, call Info-Santé 811 when in doubt (elsewhere in Canada, your provincial health line). In an emergency, call 911.

Sources

How to introduce foods, INSPQ
Food allergies in children, INSPQ
Risques d’étouffement (French only), INSPQ
Dietary exposures and allergy prevention in high-risk infants, Société canadienne de pédiatrie
Timing of introduction of allergenic solids for infants at high risk, Société canadienne de pédiatrie
Food allergy vs. food intolerance, Soins de nos enfants (SCP)
Feeding your baby in the first year, Soins de nos enfants (SCP)
Food allergies (priority allergens), Santé Canada