The best time to introduce allergenic foods to your baby is around 6 months of age, once they’re eating solids. This is a significant shift from older advice that recommended delaying allergens until age 2 or 3. The landmark LEAP trial, published in the New England Journal of Medicine, found that early peanut introduction reduced peanut allergy risk by 86% in infants who weren’t yet sensitized and by 70% in those who already showed early signs of sensitivity. Current guidelines from leading allergy and pediatric organizations recommend introducing both peanut and egg around 6 months, with no need for allergy testing beforehand in most babies.
Which Foods Count as Major Allergens
The United States recognizes nine major food allergens: milk, eggs, peanuts, tree nuts (like almonds, walnuts, and pecans), wheat, soy, fish, crustacean shellfish (like shrimp, crab, and lobster), and sesame. Sesame was added to the list in 2023. You don’t need to introduce all nine on a rigid schedule, but peanut and egg are the two with the strongest evidence for early introduction. The others can be worked in gradually over the weeks and months that follow.
Which Babies Are Higher Risk
Babies with eczema, especially severe or early-onset eczema, have a significantly higher risk of developing food allergies. Research on infants whose eczema appeared before 3 months old and required prescription-strength treatment found that roughly half of them developed a confirmed food allergy. The more severe the eczema and the earlier it starts, the stronger the connection. If your baby has moderate to severe eczema or a known egg allergy, talk to your pediatrician or allergist before introducing peanut at home. They may want to do a skin-prick test first or have you do the first feeding in a clinical setting.
How to Prepare Peanut for a Baby
Never give a baby whole peanuts, chunks of peanut butter, or a spoonful of thick peanut butter. These are all choking hazards. The goal is to deliver about 2 grams of peanut protein in a smooth, thin, baby-safe form. Here are four options from the National Institute of Allergy and Infectious Diseases, each providing that target amount:
- Thinned peanut butter: Mix 2 teaspoons of smooth peanut butter with 2 to 3 teaspoons of hot water. Stir until it’s completely dissolved and thinned out, then let it cool. Add more water if needed until it’s a runny consistency your baby can handle.
- Peanut butter in a puree: Mix 2 teaspoons of smooth peanut butter into 2 to 3 tablespoons of a fruit or vegetable puree your baby already tolerates.
- Peanut flour or powder: Stir 2 teaspoons of peanut flour or peanut butter powder into about 2 tablespoons of a familiar puree.
- Peanut puffs (like Bamba): About 21 pieces contain 2 grams of peanut protein. For babies under 7 months, soften them with 4 to 6 teaspoons of water first. Older babies who can handle dissolvable textures can eat them as-is.
How to Prepare Egg for a Baby
Egg should always be fully cooked. A simple approach: hard-boil an egg for about 5 minutes, cool it in cold water, peel it, and cut it into finger-sized strips that your baby can grip. You can also scramble an egg thoroughly or bake it into something like mini crustless quiches or omelette strips. Mashing hard-boiled egg into a puree your baby already likes works well too. The key is that no part of the egg is runny or undercooked, since raw or lightly cooked egg carries both an allergy risk and a food safety risk for infants.
The First Feeding: Step by Step
Choose a time when your baby is healthy, not fighting a cold or other illness. Mornings or early afternoons work best because you’ll want several hours to watch for any reaction before bedtime. Make sure your baby has already successfully eaten a few non-allergenic solid foods before you start with allergens.
Prepare a full serving of the allergen using one of the methods above. Offer just a small taste on the tip of a spoon, then wait 10 minutes. Watch your baby closely during those 10 minutes. If nothing happens, slowly feed the rest of the serving at your baby’s normal pace. Stay with your baby and continue watching for at least an hour after the feeding is finished.
Introduce one new allergen at a time, and wait a few days before trying the next one. This way, if a reaction does occur, you’ll know exactly which food caused it. Once an allergen has been introduced without a problem, you can combine it with other previously tolerated allergens to make ongoing feeding easier.
What an Allergic Reaction Looks Like
Symptoms can start within minutes or up to an hour after eating. Mild to moderate reactions include hives or a rash, redness or swelling around the face, vomiting, and itching or swelling of the lips, tongue, or mouth. Some babies develop worsening eczema or stomach cramps and diarrhea.
Severe reactions (anaphylaxis) are rare but require immediate emergency help. Signs include difficulty breathing or wheezing, itching or tightness in the throat, sudden extreme fussiness or limpness, and pale or bluish skin. If you see any of these signs, call emergency services right away. Do not wait to see if symptoms improve on their own. Delays in treatment for anaphylaxis increase the risk of hospitalization and serious complications. If your baby has been prescribed an epinephrine auto-injector and you’re unsure whether the reaction is severe enough, err on the side of using it. Epinephrine is safe and fast-acting, and giving it when it wasn’t strictly needed is far less dangerous than withholding it when it was.
How Often to Keep Feeding Allergens
A successful first introduction is just the beginning. To maintain your baby’s tolerance, you need to keep that food in their diet regularly. Aim to include each introduced allergen about three times per week. This doesn’t need to be a standalone feeding event. Mix peanut flour into oatmeal, stir egg into a vegetable puree, or offer yogurt as a regular snack to cover dairy. The point is consistency: sporadic exposure won’t build the same lasting tolerance as regular, repeated intake over months.
Once you’ve individually introduced several allergens, you can combine them into single meals. A pancake made with egg, wheat, milk, and a spoonful of peanut butter covers four allergens at once. This makes the process much more manageable as the list of introduced foods grows.
A Practical Timeline
Around 4 to 6 months, your baby will start showing signs of readiness for solid foods: sitting up with support, showing interest in what you’re eating, and being able to move food from the front of their mouth to the back. Start with a few simple purees like sweet potato or rice cereal. Once your baby is comfortable with a couple of basic foods, typically within a few days to a week, you can begin introducing allergens.
Start with peanut or egg, since these have the strongest evidence behind early introduction. After a successful introduction and a few days of continued exposure, move on to the next allergen. Most families can work through the major allergens over the course of a few weeks to a couple of months, depending on how quickly their baby takes to new foods. There’s no need to rush, but there’s also no benefit to waiting. The protective window for early introduction is strongest when allergens are part of the diet before 12 months of age.