How to Introduce the Top 9 Allergens to Your Baby
Introducing allergens early and keeping them in the diet reduces allergy risk. Here is how to do it, one allergen at a time.
For years parents were told to delay peanut, egg, and other allergens. The evidence reversed that. Introducing the major allergens early, around the time your baby starts solids, and keeping them in the diet regularly reduces the risk of developing food allergies. This guide covers the 9 major allergens: peanut, egg, milk (dairy), wheat, soy, tree nuts, sesame, fish, and shellfish. You will see when to start, the forms to offer, how to introduce one at a time, and how to recognize a reaction. Read the emergency section before you begin.
Reviewed against current AAP, CDC and federal guidance
Start early, then keep them in the diet
Babies get all their nutrition from breast milk or formula until around 6 months, which is usually when they are ready for solids. Once your baby tolerates a few first foods, you can begin the more allergenic foods. There is no evidence that waiting past 4 to 6 months prevents food allergy. Two things matter: introduce allergens early, and once an allergen is tolerated, keep it in the diet regularly. A one-time taste is not enough. Regular, ongoing servings are part of how early introduction protects your baby.
When to introduce peanut, by your baby's risk level
- Severe eczema means persistent or recurrent eczema that often needs prescription creams.
- Introduce age-appropriate peanut as early as 4 to 6 months.
- Talk to your pediatrician first. They will measure peanut-specific IgE (blood test) or do a skin prick test before introduction.
- A blood IgE under 0.35 kUA/L, or a skin prick wheal of 2 mm or less, generally means peanut can be introduced at home or in the office. Higher results mean supervised feeding or a specialist referral.
A test result that lands in the higher range does not mean your baby is allergic. It means the first taste belongs in a medical setting, not that peanut is off the table.
- Introduce age-appropriate peanut at around 6 months.
- This can usually be done at home.
- Discuss with your pediatrician if you have any concerns.
Most babies with mild eczema introduce peanut at home without trouble.
- Introduce peanut freely, together with other age-appropriate solid foods.
- Timing follows your family's preferences and routine.
- No testing needed.
If your baby has clear skin and no known food allergy, you do not need a special plan. Add peanut alongside other foods.
How to offer each of the 9 allergens safely
| Allergen | Safe form to offer | Avoid |
|---|---|---|
| Peanut | Smooth peanut butter thinned into cereal, pureed fruit, or yogurt; or dissolved in breast milk or formula and fed by spoon | Whole peanuts, chunky peanut butter, thick globs or spoonfuls of peanut butter |
| Egg | About 1/3 of a well-cooked egg, such as scrambled or hard-boiled, mashed or in soft pieces | Raw or undercooked egg, large firm chunks |
| Milk (dairy) | Whole-milk yogurt or Greek yogurt mixed with fruit; pasteurized cheese in soft, age-appropriate pieces | Cow's milk as a main drink before 12 months; hard cheese chunks |
| Wheat | Iron-fortified wheat or multigrain infant cereal; well-cooked soft pasta | Hard, dry, or large pieces that do not soften |
| Soy | Smooth soy yogurt, soft tofu mashed or in small soft pieces, or thinned soy butter | Firm tofu chunks, whole soy nuts |
| Tree nuts | Smooth nut butters such as cashew or almond, thinned into puree, yogurt, or cereal | Whole tree nuts, thick globs of nut butter |
| Sesame | Tahini (sesame paste) thinned into puree, yogurt, or cereal | Whole sesame seeds by the spoonful, thick tahini globs |
| Fish | Cooked, flaked, boneless fish mashed into a smooth or soft texture | Any bones, large firm pieces, raw fish |
| Shellfish | Well-cooked shellfish, finely minced or pureed into a smooth texture | Whole or large pieces, raw shellfish, rubbery chunks |
Introduce one new allergen at a time
- One new allergen at a time, then wait at least a day.
- Offer it earlier in the day so you can watch for hours afterward.
- Start small, build up, then keep it in the diet regularly.
- Foods your baby already tolerates can be served any time alongside the new one.
Signs of a reaction: call your pediatrician
- Hives, welts, or a new rash
- Flushed or itchy skin
- Vomiting or diarrhea
- Mild swelling, redness, or itching around the mouth
- Any single mild symptom that worries you
Emergency: signs of anaphylaxis
Quick answers
- What are the top 9 food allergens?
- The major food allergens are peanut, egg, milk (dairy), wheat, soy, tree nuts, sesame, fish, and shellfish. Together these account for most food allergic reactions. Each can be introduced to babies early, in smooth, soft, or thinned forms, once your baby is ready for solids around 6 months.
- When should I introduce allergens to my baby?
- Start around 6 months, once your baby tolerates a few first foods. Babies are developmentally ready for solids between 4 and 6 months. Babies at high risk for peanut allergy, meaning those with severe eczema and/or egg allergy, should have peanut introduced as early as 4 to 6 months, but only after talking with the pediatrician, who may test peanut-specific IgE or do a skin prick test first. There is no evidence that delaying allergens past 4 to 6 months prevents allergy.
- How do I introduce peanut to a baby safely?
- Never give whole peanuts or thick globs of peanut butter, which are choking hazards. Instead, thin a small amount of smooth peanut butter into infant cereal, pureed fruit, or yogurt, or dissolve it in breast milk or formula and feed it by spoon. Start with a small taste, watch for a reaction, then build up to a regular serving such as about 2 teaspoons of peanut butter and keep it in the diet routinely.
- Should I introduce one allergen at a time?
- Yes. Give one new allergenic food at a time and wait at least a day before starting another. This way, if a reaction happens, you know which food caused it. Offer new allergens earlier in the day so you can watch your baby for several hours while awake. Foods your baby already tolerates can be served alongside the new one.
- What does an allergic reaction look like in a baby?
- Mild reactions usually appear within minutes to a couple of hours and include hives, a new rash, flushed or itchy skin, vomiting, or diarrhea. Stop the food and call your pediatrician. Severe reactions (anaphylaxis) include trouble breathing, wheezing, swelling of the lips or tongue, trouble swallowing, pale or bluish skin, weak pulse, or repeated vomiting. A baby may also drool suddenly, cry inconsolably, go limp, or become unusually sleepy.
- What should I do if my baby has a severe allergic reaction?
- Treat it as an emergency. If epinephrine has been prescribed, give it immediately, then call 911 and go to the emergency department. If there is no prescribed epinephrine but your baby shows signs of anaphylaxis such as trouble breathing or swelling, call 911 right away. Keep your baby lying down, or on their side if vomiting. Stay with your baby and give a second dose of epinephrine if symptoms get worse or do not improve within 5 minutes.
- Do I need to keep feeding allergens after introducing them?
- Yes. Early introduction works together with keeping the allergen in the diet regularly. A single taste is not enough. Once your baby tolerates an allergen, serve it in age-appropriate portions on an ongoing basis. If you stop, the protective effect can fade and the allergy risk may return.
Sources & further reading
Log every feed and first food.
ParentFlow tracks feeds, solids, and reactions, so you can see the pattern.
App Store Google Play Open Web AppThis guide reflects current AAP, CDC and federal guidance and is for educational purposes only. It does not constitute medical or legal advice. ParentFlow is a wellness companion — not a substitute for your pediatrician. For any medical concern, contact your healthcare provider.