Why the advice changed
For years, parents were told to hold off on peanut, egg, and other allergens until well past the first birthday. Then a large study called LEAP found that babies at high risk who ate peanut regularly from infancy were far less likely to develop a peanut allergy than babies who avoided it. U.S. guidelines from the National Institute of Allergy and Infectious Diseases (2017) and later guidance from the American Academy of Pediatrics now support introducing peanut and other allergens early—around the time solids start—rather than delaying.
This is general information, not medical advice for your child. Talk with your pediatrician before you start, especially if your baby has any of the risk factors below.
Check your baby’s risk first
Most babies can start allergens at home. Talk to your pediatrician before the first taste if your baby has:
- Severe eczema (widespread, frequent, or needing prescription creams)
- A known food allergy, such as a reaction to egg
- A past reaction to any food that worried you
These babies are at higher risk for peanut allergy, and the doctor may recommend allergy testing or a first taste in the office. Babies with mild eczema or no risk factors can usually start peanut at home once they are eating other solids.
When to start
Most babies start solids around six months, and allergens can be part of the plan from the beginning. Guidance supports introducing them around four to six months for many babies, but not before four months, and only once your baby shows readiness: good head control, sitting with support, and interest in food. Offer a couple of easy first foods (like iron-fortified cereal, mashed vegetables, or fruit) before the first allergen so you know solids in general are going well.
The common allergens
In the U.S., nine foods cause most allergic reactions: milk, egg, peanut, tree nuts, soy, wheat, fish, shellfish, and sesame. You don’t need to rush through all nine in a week. Peanut and egg get the most attention because early introduction has the strongest evidence behind it.
Safe, baby-friendly forms
The rule: allergens should be in a texture your baby can safely manage. Whole nuts, spoonfuls of thick nut butter, and hard chunks are choking hazards for babies and toddlers.
- Peanut — Thin about 2 teaspoons of smooth peanut butter with warm water, breast milk, or formula until it is runny, or stir peanut powder into a food your baby already eats, like oatmeal or applesauce.
- Egg — Fully cooked egg only: a hard-boiled egg mashed with a little breast milk or formula, or soft scrambled egg cooked through. Skip runny yolks.
- Milk — Plain whole-milk yogurt or small amounts of soft cheese. Cow’s milk as a main drink waits until 12 months.
- Wheat — Wheat cereal, soft pasta, or toast strips.
- Soy — Mashed soft tofu or plain soy yogurt.
- Tree nuts — Thinned smooth almond or cashew butter, or finely ground nut powders mixed into food.
- Sesame — A little tahini thinned and stirred into yogurt, hummus, or puree.
- Fish and shellfish — Flaked, well-cooked, low-mercury fish such as salmon or cod; finely chopped cooked shrimp.
A simple way to introduce each one
- Pick a calm morning at home, when your baby is healthy and you can watch them for a couple of hours afterward. Avoid starting a new allergen right before daycare, a car ride, or bedtime.
- Offer a small taste on the tip of a spoon mixed into a food they already like.
- Wait about 10 minutes and look for any reaction.
- If all is well, offer the rest of the small serving at the usual pace.
- Wait a few days before adding the next new allergen, so if something happens, you know what caused it.
A simple note on your phone with the food, the date, and how it went keeps track without much effort.
Know the signs of a reaction
Mild reactions can include a few hives around the mouth or face, or a new rash. Stop the food and call your pediatrician for guidance before offering it again.
Call 911 if you see signs of a serious reaction, which can happen quickly:
- Trouble breathing, wheezing, or repeated coughing
- Swelling of the lips, tongue, or face
- Widespread hives
- Repeated vomiting
- Pale or bluish skin, floppiness, or unusual sleepiness
Redness from food smeared on the skin is common and usually fades quickly. When in doubt, call.
Keep it in the diet
This is the step most families miss. Introducing an allergen once is not enough—the protective effect seems to come from eating it regularly. Once a food goes well, aim to offer it a few times a week. For peanut, the NIAID guidelines describe a typical amount as about 2 teaspoons of smooth peanut butter (roughly 2 grams of peanut protein), offered about three times a week.
Build allergens into regular meals so it isn’t extra work:
- Stir thinned peanut butter into oatmeal on Mondays and Thursdays.
- Make egg part of a weekend breakfast. Our busy morning breakfast ideas include several that use egg.
- Add tahini to a family hummus night, and yogurt to snack time.
- Use flaked salmon in a weekly dinner and serve your baby a soft portion.
Mealtime setup tips
Allergen tastes are easier when the setup is predictable: a stable high chair, a clean surface, and food in one spot. Wipe the tray and your baby’s hands and face after allergen meals so traces don’t end up on siblings, toys, or the couch. If you are doing baby-led weaning, see our high chair setup guide for seating and positioning basics.
Keep siblings in the loop too. Older kids with food allergies need their own plan, and toddlers should know not to share snacks with babies.
Myths to skip
- “Waiting is safer.” For most babies, current evidence points the other way.
- “One taste is enough.” Regular exposure matters.
- “Rubbing peanut on the skin tests for allergy.” It doesn’t, and it isn’t recommended.
- “Allergens must be introduced in a doctor’s office.” Only some higher-risk babies need that.
Put it into practice this week
Ask your pediatrician at the next visit whether your baby has risk factors. Once you are cleared and solids are going well, choose one calm morning, mix thinned peanut butter into a familiar food, and watch for reactions. Add egg a few days later. Then put both on the weekly plan.
The bottom line
For most babies, introducing common allergens early, in safe textures, one at a time, and then keeping them in the diet is the current best practice. Check risk factors with your doctor first, know the warning signs, and treat allergens like any other regular food on the menu.