Food Allergy Reactions in Babies: What to Know and How to Respond

Introducing solid foods is exciting—but concerns about food allergies can make it anxiety-inducing. Understanding what allergic reactions look like, how to respond, and how to safely introduce allergenic foods can help you navigate this phase with more confidence and less fear.

Understanding Food Allergies vs. Intolerances

These are different things: AAP

Food allergy:

• Immune system reaction
• Can be severe or life-threatening
• Usually appears quickly (within minutes to 2 hours)
• Involves IgE antibodies (most common type)
• Common allergens: peanuts, tree nuts, milk, eggs, wheat, soy, fish, shellfish, sesame

Food intolerance:

• Digestive system issue
• Uncomfortable but not dangerous
• Usually delayed reaction
• Doesn't involve immune system
• Example: lactose intolerance

Food sensitivity:

• Vaguer symptoms
• Often delayed
• Hard to diagnose
• Not life-threatening

This guide focuses on true food allergies, which require the most vigilance.

How Common Are Food Allergies?

The numbers: AAP

• About 6-8% of children under 3 have a food allergy
• Peanut allergy: ~2% of children
• Milk allergy: ~2-3% of infants (most outgrow it)
• Egg allergy: ~1-2% of children (most outgrow it)
• Tree nut allergy: ~1% of children

Risk factors for food allergies:

• Family history of allergies, eczema, or asthma
• Personal history of eczema (especially moderate-severe)
• Previous allergic reaction to a food
• Existing food allergy (raises risk of another)

Recognizing Allergic Reactions

Symptoms can range from mild to severe: AAP

### Mild to Moderate Symptoms

Skin:

• Hives (raised, red, itchy welts)
• Eczema flare-up
• Redness around mouth
• Swelling of face, lips, eyes

Digestive:

• Vomiting
• Diarrhea
• Stomach pain
• Nausea

Other:

• Runny or stuffy nose
• Sneezing
• Itchy, watery eyes
• Itchy mouth or throat

### Severe Symptoms (Anaphylaxis)

Call 911 immediately if you see:

• Difficulty breathing
• Wheezing or shortness of breath
• Throat tightness or hoarse voice
• Repetitive coughing
• Swelling of tongue or throat
• Pale or blue skin color
• Dizziness or fainting
• Confusion
• Loss of consciousness
• Weak pulse
• Symptoms in multiple body systems simultaneously

Anaphylaxis can progress rapidly and be life-threatening. Don't wait to see if it gets better.

### Timing of Reactions

Immediate reactions (IgE-mediated):

• Usually within minutes to 2 hours of eating
• Most common type
• Can be severe

Delayed reactions:

• Hours to days after eating
• More common with milk and soy
• Usually gastrointestinal symptoms
• Generally not life-threatening

What to Do If a Reaction Occurs

### For Mild Reactions

If you see hives, mild swelling, or gastrointestinal symptoms: AAP

1. Stop feeding the suspected food
2. Watch baby closely for progression
3. Antihistamine (like Benadryl) may help hives—ask your pediatrician about dosing
4. Call your pediatrician to report the reaction and get guidance
5. Note what baby ate, when, and what symptoms occurred

### For Severe Reactions

If you see any signs of anaphylaxis: AAP

1. Call 911 immediately
2. If you have an epinephrine auto-injector (EpiPen), use it
3. Lay baby down with legs elevated (unless having breathing difficulty)
4. Be prepared to give a second epinephrine dose if symptoms don't improve
5. Go to the emergency room even if symptoms improve—reactions can return

Important: After a severe reaction, your child will be prescribed an epinephrine auto-injector to carry at all times.

Introducing Allergenic Foods Safely

The approach to allergen introduction has changed dramatically: AAP

### Current Guidelines

What we now know:

• Early introduction of allergens may PREVENT allergies
• Delaying allergenic foods doesn't reduce risk—and may increase it
• Introduce common allergens around 6 months (not before 4 months)
• This is especially important for high-risk babies (those with eczema or egg allergy)

### How to Introduce Allergens Safely

General principles:
1. Introduce one new allergen at a time
2. Start with small amounts
3. Give when baby is healthy (not sick or very fussy)
4. Introduce at home, not at daycare or restaurant
5. Wait 2-3 days before introducing another new allergen
6. Watch for reactions
7. If tolerated, continue giving regularly (at least weekly)

For peanut introduction:

• Use peanut butter or peanut powder (never whole peanuts)
• Mix with breast milk, formula, or pureed food
• Start with a small amount (tip of a spoon)
• Wait 10 minutes, offer more if no reaction
• Watch for 2 hours after eating

For high-risk babies:

• Discuss with pediatrician before introducing peanuts
• May need allergy testing first
• May benefit from supervised first exposure

### The "Two-Bite Rule"

Some allergists recommend: AAP
1. Give a small taste and wait 10 minutes
2. If no reaction, give a larger amount
3. Watch closely for 2 hours
4. If any reaction occurs, stop and call your doctor

After a Reaction: What's Next?

If your baby has had an allergic reaction: AAP

Immediate steps:
1. Avoid the suspected food until you see a doctor
2. Document exactly what was eaten and what happened
3. Take photos of any visible reactions (hives, swelling)
4. Call your pediatrician

Medical follow-up:

• Referral to a pediatric allergist
• Skin prick testing and/or blood tests
• Possible oral food challenge (under medical supervision)
• Action plan for future exposures
• Prescription for epinephrine auto-injector if warranted
• Education on reading food labels

Living with a Food Allergy

If your baby is diagnosed with a food allergy: AAP

Label reading:

• Learn all the names for the allergen
• Check every product, every time (formulations change)
• "May contain" warnings should be taken seriously

Cross-contamination:

• Clean surfaces and utensils thoroughly
• Separate preparation of allergen-free foods
• Be cautious at restaurants and social gatherings

Education:

• Teach family members about the allergy
• Ensure childcare providers understand and have an action plan
• Carry emergency medication at all times

Hope for the future:

• Many children outgrow milk, egg, wheat, and soy allergies
• Peanut and tree nut allergies are more likely to persist
• Regular re-evaluation with your allergist determines if allergy has resolved

Common Questions

"Should I avoid allergens while breastfeeding?"
Generally no. Current evidence doesn't support maternal avoidance during breastfeeding to prevent allergies. Only avoid if your baby has shown a reaction to something in your breast milk. AAP

"Can I tell from a blood test if my baby will be allergic?"
Blood tests (and skin tests) can indicate sensitization, but don't always predict clinical reaction. Many children test positive but can eat the food without problems. Allergists interpret these results in context.

"What about allergies to fruits and vegetables?"
Less common and usually milder. Oral allergy syndrome (itchy mouth with raw fruits/vegetables) is related to pollen allergies and usually manageable.

"If my baby had a mild reaction, could the next one be severe?"
Possibly. Reaction severity can vary between exposures. This is why even mild reactions warrant medical follow-up and precautions.

The Bottom Line

Food allergies are concerning but manageable. Early introduction of allergens is now recommended as a prevention strategy. Know the signs of allergic reactions, have a plan for responding, and work with your pediatrician and allergist to keep your baby safe.

Most importantly: don't let fear of allergies prevent you from offering a variety of foods. The benefits of early allergen introduction outweigh the risks for most babies.

Clara is here to help you navigate introducing allergens or managing a diagnosed food allergy.