Introducing Allergens & Managing Food Allergies in Babies

Current evidence shows that early introduction of common allergens reduces allergy risk. This guide covers which allergens to introduce, how to do it safely, what reactions look like, and what to do if your baby has a food allergy.

Content reviewed against published AAP, NIAID, CDC, ACAAI guidelines

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Key takeaways

  • Introduce common allergens (peanut, egg, dairy, etc.) early - around 6 months - to reduce allergy risk, not increase it.
  • The LEAP study showed early peanut introduction reduced peanut allergy by up to 81% in high-risk infants.
  • Introduce one new allergen every 2-3 days so you can identify which food caused any reaction.
  • Babies with moderate-to-severe eczema are at higher allergy risk and may benefit from earlier introduction (4-6 months) with pediatrician guidance.
  • Know the difference between mild reactions (hives, vomiting) and anaphylaxis (breathing difficulty, widespread swelling) - call 911 for severe reactions.

The top 9 food allergens

These nine foods account for approximately 90% of all food allergies. Introduce them one at a time, with 2-3 days between each new allergen.

Peanuts

Thin peanut butter mixed into puree, or peanut puffs

Eggs

Well-cooked scrambled egg, starting with a small amount

Cow's milk (dairy)

Plain whole-milk yogurt or cheese (not milk as a drink before 12mo)

Tree nuts

Thin almond/cashew butter mixed into puree

Wheat

Infant cereal, soft bread strips, or pasta

Soy

Pureed tofu or foods made with soy

Fish

Well-cooked, flaked salmon or white fish

Shellfish

Well-cooked, finely minced shrimp

Sesame

Tahini mixed into puree or hummus

How to introduce allergens safely

  1. Choose a calm day - Introduce new allergens at home (not at daycare or a restaurant) when baby is healthy and happy
  2. Start small - Offer a tiny amount (1/4 to 1/2 teaspoon) mixed into a food baby already tolerates
  3. Wait and watch - Observe for 10-15 minutes after the first taste. Most allergic reactions occur within minutes to 2 hours
  4. Increase if no reaction - If tolerated, offer a larger portion and continue the meal
  5. Continue offering regularly - Give the allergen 2-3 times per week to maintain tolerance. Stopping can increase risk of developing an allergy later
  6. Introduce early in the day - This way you can monitor for delayed reactions while baby is awake

Recognizing allergic reactions

Mild to moderate reactions

Usually appear within minutes to 2 hours. Contact your pediatrician.

  • Hives (red, raised, itchy bumps) on face or body
  • Mild swelling of lips, eyes, or face
  • Vomiting (single episode)
  • Redness or rash around the mouth
  • Eczema flare-up
  • Runny nose or sneezing

Severe reactions (anaphylaxis) - Call 911

Rare in babies but requires immediate emergency care.

  • Difficulty breathing, wheezing, or persistent cough
  • Swelling of tongue or throat
  • Widespread hives covering most of the body
  • Pale or blue coloring
  • Sudden limpness or loss of consciousness
  • Repeated vomiting with other symptoms

High-risk babies: What to know

Your baby may be at higher risk for food allergies if they have:

  • Moderate to severe eczema (especially if it appeared before 6 months)
  • A diagnosed egg allergy
  • A sibling or parent with food allergies

NIAID guidelines for high-risk infants

  • Consider introducing peanut as early as 4-6 months
  • Discuss allergy testing (skin prick or blood test) with your pediatrician before introduction
  • Some high-risk babies may have their first exposure in a medical setting
  • Even with confirmed allergy risk, early supervised introduction often reduces long-term allergy development

If your baby is diagnosed with a food allergy

  • Work with an allergist - They can confirm the diagnosis and develop a management plan
  • Learn to read labels - Allergens can appear under many names (e.g., casein = milk, albumin = egg)
  • Create an action plan - Know exactly what to do in case of accidental exposure
  • Carry epinephrine if prescribed - Ask about an EpiPen Jr. for severe allergies
  • Inform all caregivers - Daycare, grandparents, and babysitters all need to know about the allergy
  • Many children outgrow allergies - Milk, egg, wheat, and soy allergies are often outgrown by age 5; peanut and tree nut allergies are more likely to persist

Frequently asked questions

When should I introduce allergenic foods to my baby?
Current guidelines recommend introducing common allergens around 6 months of age (or when baby starts solids), not delaying them. The LEAP study showed that early introduction of peanut (between 4-11 months) reduced peanut allergy risk by up to 81% in high-risk infants. Introduce one new allergen every 2-3 days so you can identify any reactions.
What are the top allergens to introduce to babies?
The top 9 allergens (responsible for 90% of food allergies) are: peanuts, tree nuts, milk (dairy), eggs, wheat, soy, fish, shellfish, and sesame. You do not need to introduce them in any specific order, but peanut and egg are often prioritized since early introduction has the strongest evidence for allergy prevention.
How do I introduce peanuts to my baby safely?
Never give whole peanuts or chunky peanut butter (choking hazard). Instead, mix a small amount of smooth peanut butter (about 1/2 teaspoon) with breast milk, formula, or pureed fruit to thin it. Peanut puffs dissolved in saliva are also safe. Offer a small amount first, wait 10-15 minutes, then give more if no reaction occurs. Continue offering 2-3 times per week.
What does a food allergy reaction look like in babies?
Mild reactions include: hives (red raised bumps), facial swelling, vomiting, increased fussiness, or eczema flare-up within minutes to 2 hours of eating. Severe reactions (anaphylaxis, rare in babies) include: difficulty breathing, throat swelling, widespread hives, loss of consciousness, or pale/blue coloring. Call 911 immediately for severe reactions.
Should I avoid allergens if my baby has eczema?
No - in fact, babies with moderate to severe eczema are at higher risk for food allergies, and early introduction is even more important for them. The AAP and NIAID guidelines recommend introducing peanut as early as 4-6 months for high-risk babies (those with severe eczema or egg allergy), potentially after allergy testing. Talk to your pediatrician.
Is there a difference between food allergy and food intolerance?
Yes. A food allergy involves the immune system and can be life-threatening (reactions include hives, swelling, breathing difficulty). A food intolerance involves the digestive system and causes discomfort but is not dangerous (symptoms include gas, bloating, loose stools). Cow's milk protein allergy is immune-mediated; lactose intolerance is digestive.

Bottom line

Introduce common allergens early (around 6 months) and often to reduce allergy risk - do not delay. Start with small amounts at home, one new allergen every 2-3 days, and continue offering regularly. If your baby has eczema or family history of allergies, early introduction is even more important. Talk to your pediatrician about the best approach for your baby.

Trust your instincts. If something feels wrong, reach out to your pediatrician. Worrying about your baby means you care — that is a good thing.

All content follows our editorial policy and is reviewed against published clinical guidelines.

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