Introducing allergens: peanut, egg and the rest

Common food allergens (peanut, egg, milk…), when and how to introduce them, signs of a reaction and of an emergency

Reviewed October 19, 2026against 3 sources, listed below

When to call

Call 911 for anaphylaxis: trouble breathing, throat tightness, fainting or confusion, unresponsive. Epinephrine right away if prescribed, then call 911. An antihistamine never replaces epinephrine.

The foods behind most food allergies: cow's milk, eggs, peanuts, soy, wheat, tree nuts, fish and shellfish, and sesame.
Starting around 6 months, offering these foods can help lower the risk of food allergy; delaying them may actually raise it.
Babies with eczema or a family history of allergies: check with the pediatrician first. For severe eczema and/or egg allergy, peanut allergy testing is recommended before peanut.
Introduce one new food at a time, in small amounts, and watch for a reaction; the CDC says wait 3 to 5 days between new foods, and bring in the allergenic ones (eggs, shellfish, nut butters, wheat) alongside other foods rather than holding them back.
Peanut never as whole nuts or chunks of peanut butter (both choking hazards).
Signs of a reaction: hives, itchy rash, swelling; sneezing, coughing, wheezing; in babies also excessive crying, eye rubbing, arching the back, going floppy.

Log each new food on the day it's offered: you'll see which allergens are in, and can tell the pediatrician exactly what came before a reaction.

Education from the sources listed, not medical advice. If you're worried about your child, call your pediatrician; in an emergency, call 911.