The best time to introduce allergenic foods to your baby is early, right around 6 months of age when they start solids. Waiting longer does not protect against allergies. In fact, introducing foods like peanut, egg, and dairy early can actually reduce the risk of your baby developing a food allergy. Here’s how to do it safely.
When to Start
Most babies are ready for solid foods around 6 months old, and that’s the right time to begin introducing allergenic foods alongside other first foods. There’s no benefit to holding off on allergens until later. For babies at higher risk of peanut allergy (those with severe eczema, an existing egg allergy, or both), peanut-containing foods should ideally be introduced even earlier, between 4 and 6 months.
Signs your baby is ready for solids include holding their head steady, sitting with support, showing interest in food, and opening their mouth when food is offered. Each baby develops on their own timeline, so readiness matters more than hitting an exact date on the calendar.
The Nine Major Allergens
The nine foods most likely to cause allergic reactions are:
- Milk (cow’s milk in foods, not as a drink replacement for breast milk or formula)
- Eggs
- Peanuts
- Tree nuts (almonds, cashews, walnuts, etc.)
- Soy
- Wheat
- Fish
- Shellfish
- Sesame
You don’t need to introduce all nine at once. Work through them one at a time over the course of several weeks, prioritizing peanut and egg since those are the most common allergies in young children and the ones with the strongest evidence for early introduction.
The One-at-a-Time Rule
Introduce one new allergenic food every 3 to 5 days. This spacing gives you a clear window to watch for any reaction. If your baby develops hives, vomiting, or swelling after trying a new food, you’ll know exactly which food caused it. During those 3 to 5 days, you can keep feeding foods your baby has already tolerated without issue.
Start with a small taste. You don’t need to give a full serving on the first try. Offer a tiny amount, wait about 10 minutes, and if there’s no reaction, give a little more. Try new allergens earlier in the day rather than right before bedtime so you have plenty of time to observe your baby afterward.
How to Prepare Allergens Safely
Whole peanuts, spoonfuls of peanut butter, and whole nuts are all choking hazards for babies. You need to modify the texture to make them safe.
For peanut, mix a small amount of smooth peanut butter into infant cereal, pureed fruit, or plain yogurt until it’s thin and easy to swallow. You can also dissolve a small amount in breast milk or formula and feed it by spoon. Peanut puff snacks designed for babies are another safe option once your baby can handle dissolvable solids.
For egg, start with well-cooked forms. A hard-boiled egg cooked for at least 10 minutes (so both the white and yolk are fully set) can be mashed and mixed into other foods your baby already eats. Scrambled eggs cooked all the way through also work well. You can bake egg into mini muffins or pancakes too. Avoid runny or undercooked eggs for young babies.
For dairy, a small amount of plain whole-milk yogurt or soft cheese is the easiest starting point. Cow’s milk shouldn’t replace breast milk or formula as a drink until after 12 months, but it’s fine as an ingredient in food.
For wheat, mix a small amount of iron-fortified wheat cereal into a puree your baby already likes. For soy, a bit of silken tofu blended smooth works well. For sesame, thin a small amount of tahini (sesame paste) into a puree, the same way you’d thin peanut butter. For fish, offer a small flake of well-cooked, deboned fish mashed into something soft.
What Higher-Risk Babies Need
If your baby has severe eczema, an egg allergy, or both, they’re at higher risk for developing a peanut allergy. For these babies, the FDA recommends introducing peanut-containing foods as early as 4 to 6 months, because early exposure significantly reduces the risk of peanut allergy developing later.
Before you introduce peanut to a higher-risk baby, talk to their pediatrician. A blood test or skin prick test may be recommended first to check whether your baby is already sensitized to peanut. Based on the results, the doctor can tell you the safest way to proceed. Some higher-risk babies may need to have their first taste of peanut in a clinical setting rather than at home.
Babies without eczema or a known food allergy can generally start peanut and other allergens at home around 6 months without prior testing.
Keep Feeding Allergens After the First Taste
Introduction is only the first step. After your baby tolerates a food, keep it in their diet regularly. The protective effect comes not just from the first exposure but from continued eating during infancy and toddlerhood.
The good news is that you don’t need to be rigid about it. Research from the landmark LEAP study, published by the National Institute of Allergy and Infectious Diseases, followed children from infancy into adolescence and found that the protective effect of early peanut consumption lasted even when kids went through periods of not eating peanut products. The frequency and amount varied widely among participants, and the benefit held. So aim to offer allergenic foods a few times per week, but don’t stress if you miss some days or even a week here and there.
A practical approach: rotate through the allergens your baby has already tolerated as part of regular meals. Peanut butter mixed into oatmeal one morning, yogurt as a snack, scrambled eggs another day, a bit of fish with dinner. Building these foods into your normal routine is more sustainable than following a strict schedule.
What a Reaction Looks Like
Mild reactions are more common than severe ones. You might notice a few hives around the mouth, minor redness, or a little spit-up. These don’t always mean your baby has a true allergy, but they do mean you should stop offering that food and bring it up with your pediatrician before trying again.
A severe allergic reaction (anaphylaxis) is rare but serious. Signs include widespread hives or swelling, difficulty breathing, wheezing, repeated vomiting, sudden limpness, or pale or bluish skin. If you see any of these, call emergency services immediately. This is why introducing allergens during the day, when you’re alert and able to observe your baby closely, is a sensible precaution.