Introducing Allergens to Baby: A Safe Step-by-Step Guide

The guidelines have changed. For years, parents were told to delay allergenic foods. Now we know that early introduction—starting around 4-6 months—may actually help prevent allergies from developing.

But “introduce allergens early” is easier said than done. Which ones first? How much? What if something goes wrong?

This guide walks you through introducing the top allergens safely and confidently. Knowledge replaces fear when you have a clear plan.

Why Early Introduction Matters

The science: Landmark studies (including LEAP and EAT) found that introducing peanuts and other allergens early significantly reduced allergy rates. Delaying introduction may actually increase risk.

Current recommendations: The American Academy of Pediatrics now recommends introducing allergenic foods around 4-6 months, alongside other solid foods.

The window: There appears to be a critical window in infancy when the immune system learns to tolerate foods. Missing this window may increase allergy risk.

Important caveat: Babies with severe eczema or existing food allergies may need testing before introduction. Talk to your pediatrician about your specific situation.

The Top 9 Allergens

These foods account for 90% of food allergies:

Peanuts
Tree nuts (almonds, cashews, walnuts, etc.)
Milk (cow’s milk protein)
Eggs
Wheat
Soy
Fish
Shellfish
Sesame

Note: While these are the “big 9,” any food can potentially cause an allergic reaction.

Before You Begin

Talk to Your Pediatrician If:

Baby has moderate to severe eczema
Baby has a known food allergy
Baby has had a previous allergic reaction to any food
There’s a strong family history of food allergies
You’re concerned for any reason

Some babies may need allergy testing before introduction. Your pediatrician can guide you.

Signs Baby Is Ready for Solids

Before introducing ANY solid food (allergenic or not), ensure baby:

Is at least 4 months old (6 months is often ideal)
Can hold head up steadily
Shows interest in food
Has lost the tongue-thrust reflex
Can sit with support

What You’ll Need

The allergenic food in age-appropriate form
A timer or clock
Benadryl (diphenhydramine) on hand—know the correct dosing for baby’s weight
Your pediatrician’s after-hours number
Knowledge of nearest emergency room

[INTERNAL LINK: baby-led-weaning-guide]

How to Introduce Each Allergen

General Protocol

Step 1: Start small

Begin with a very small amount—about 1/4 teaspoon mixed into a food baby already tolerates.

Step 2: Watch and wait

Observe for at least 2 hours after introduction. Most reactions occur within this window.

Step 3: Increase gradually

If no reaction, slowly increase amount over subsequent exposures.

Step 4: Maintain exposure

Once introduced, continue offering 2-3 times per week. Irregular exposure may increase risk.

Step 5: One at a time

Wait 2-3 days between introducing new allergens. This helps identify the culprit if a reaction occurs.

Timing Tips

Introduce early in the day (easier to monitor)
Don’t introduce when baby is sick
Don’t introduce when you’re stressed or rushed
Have another adult present if possible

Introducing Specific Allergens

Peanuts

Why it matters: Peanut allergies have increased dramatically. Early introduction reduces risk by up to 80% in high-risk infants.

Age to introduce: 4-6 months (earlier end for high-risk babies with pediatrician guidance)

Safe forms:

Peanut butter thinned with breast milk, formula, or water
Peanut puff snacks (like Bamba)
Peanut butter powder mixed into purees

Never give: Whole peanuts or chunky peanut butter (choking hazard until age 4+)

How to serve:

Mix 2 teaspoons of peanut butter with 2-3 tablespoons of warm water until smooth. Start with 1/4 teaspoon of this mixture.

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Eggs

Safe forms:

Well-cooked scrambled eggs (mashed or in small pieces)
Hard-boiled egg yolk mixed into puree
Baked goods containing egg

Never give: Raw or runny eggs

How to serve:

Start with 1/4 teaspoon of well-cooked scrambled egg or mashed hard-boiled yolk.

Note: Some babies react to egg white but tolerate yolk. If reaction occurs, consult your pediatrician.

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Cow’s Milk

Important distinction: This refers to milk protein, not milk as a drink.

Safe forms:

Full-fat plain yogurt
Cheese (soft varieties, small pieces)
Milk cooked into foods

Never give: Cow’s milk as a drink before 12 months (nutritional reasons, separate from allergy)

How to serve:

Start with 1/4 teaspoon of plain full-fat yogurt.

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Tree Nuts

Safe forms:

Nut butters thinned with water or breast milk
Finely ground nuts mixed into purees
Nut butter powder

Never give: Whole nuts or nut pieces (choking hazard until age 4+)

How to serve:

Same as peanut butter—thin with liquid, start with tiny amount.

Note: Introduce each tree nut separately. Allergy to one doesn’t mean allergy to all.

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Wheat

Safe forms:

Infant oatmeal made with wheat flour
Soft, small pieces of toast or bread
Wheat pasta cooked very soft

How to serve:

Start with infant cereal containing wheat, or soft bread pieces for baby-led weaning.

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Soy

Safe forms:

Tofu (soft, small cubes)
Edamame (mashed or pureed, NEVER whole—choking hazard)
Soy-based formula (if using)

How to serve:

Start with silken tofu mashed into a puree baby already eats.

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Fish

Safe forms:

Well-cooked, flaky fish mashed or pureed
Start with mild white fish (cod, tilapia)
Ensure no bones

How to serve:

Mash a small amount of well-cooked fish into puree, or offer soft flakes for baby-led weaning.

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Shellfish

Safe forms:

Well-cooked shrimp or crab, pureed or finely minced
Ensure thoroughly cooked

How to serve:

Start with a very small amount of pureed well-cooked shrimp.

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Sesame

Safe forms:

Tahini (sesame paste) thinned with water
Hummus (contains tahini)
Sesame seeds ground into purees (whole seeds are choking hazard)

How to serve:

Mix a tiny amount of tahini into a puree, or offer hummus as a spread or dip.

Recognizing Allergic Reactions

Mild to Moderate Symptoms

(Usually appear within minutes to 2 hours)

Hives (red, itchy bumps)
Rash around mouth or body
Swelling of lips, face, or eyes
Vomiting
Diarrhea
Increased eczema
Runny nose
Stomach pain (baby seems uncomfortable, crying)

What to do: Stop feeding the food. Monitor closely. Call your pediatrician for guidance.

Severe Symptoms (Anaphylaxis)

CALL 911 IMMEDIATELY if you see:

Difficulty breathing
Wheezing
Swelling of throat or tongue
Severe vomiting
Pale or blue color
Sudden drowsiness or floppiness
Loss of consciousness

Anaphylaxis is rare but life-threatening. Don’t wait to see if it gets better.

[INTERNAL LINK: homemade-baby-food-recipes]

Creating an Introduction Schedule

Sample 8-Week Plan

Week 1: Peanut

Day 1: First small introduction
Day 3: Second exposure (slightly more)
Day 5: Third exposure
Continue 2-3x/week ongoing

Week 2: Egg

Same protocol

Week 3: Milk (yogurt)

Same protocol

Week 4: Tree nut (choose one, like almond)

Same protocol

Week 5: Wheat

Same protocol

Week 6: Soy

Same protocol

Week 7: Fish

Same protocol

Week 8: Sesame

Same protocol

Continue: Once introduced, keep all allergens in regular rotation (2-3x/week each).

The Ongoing Rotation

After introduction, maintaining exposure is crucial. Here’s how to keep allergens in the diet:

Breakfast ideas:

Oatmeal with peanut butter
Scrambled eggs
Yogurt with wheat cereal

Lunch ideas:

Hummus with soft pita
Cheese and crackers
Tofu stir fry

Dinner ideas:

Salmon (fish)
Pasta (wheat)
Edamame as side (soy)

Snacks:

Nut butter on banana
Bamba puffs
Cheese sticks

FAQ

What if there’s a family history of allergies?

Talk to your pediatrician. Some babies with high risk may need testing before introduction. But even high-risk babies often benefit from early introduction—just with medical guidance.

My baby has eczema. Should I wait?

Actually, babies with eczema are at higher risk for food allergies, which makes early introduction potentially more important. Consult your pediatrician—they may recommend earlier introduction and/or testing.

What if baby doesn’t like an allergenic food?

Keep trying in different forms. The goal is exposure, not enthusiasm. A small amount mixed into accepted foods counts.

How long do I need to keep offering allergens?

Ideally through toddlerhood and beyond. Regular exposure seems to maintain tolerance.

Can I introduce multiple allergens in one day?

It’s safest to wait 2-3 days between NEW allergens. But once all are introduced without reaction, combining in meals is fine.

What if my baby had a mild reaction?

Don’t reintroduce without consulting your pediatrician. They may recommend testing or supervised reintroduction.

Are allergen introduction products worth it?

Products like SpoonfulOne or Ready Set Food can be convenient, but they’re not necessary. You can introduce allergens effectively with regular foods.

Conclusion

Introducing allergens can feel scary, but the evidence is clear: early, consistent introduction is one of the best things you can do to reduce your baby’s allergy risk.

Start small. Watch carefully. Keep exposure consistent. And remember—you’re giving your baby’s immune system the chance to learn tolerance during a critical window.

Talk to your pediatrician, make a plan, and introduce with confidence. Most babies do beautifully—and you’re doing something genuinely protective for their future.

[INTERNAL LINK: healthy-toddler-snack-ideas]

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Introducing Allergens to Baby: A Safe Step-by-Step Guide

Why Early Introduction Matters

The Top 9 Allergens