Key takeaways
- Early peanut introduction for baby around 6 months reduces the risk of developing peanut allergy by 81% (the landmark LEAP trial).
- Never give a baby whole peanuts or undiluted globs of thick peanut butter—both are severe choking hazards. Always thin smooth peanut butter with warm water, breast milk, formula, or yogurt.
- Once tolerated, serve peanut protein at least 2 to 3 times per week (around 2 teaspoons of peanut butter per week total) to maintain immune tolerance.
Peanut allergy is one of the most common and persistent IgE-mediated food allergies in children. For parents preparing for weaning, knowing how to introduce peanut butter to baby safely is one of the highest-impact preventive health steps of the entire first year.
Thanks to the landmark LEAP trial, paediatricians and allergy societies worldwide now recommend proactive peanut introduction for baby at around six months of age—once your baby shows all signs of readiness for solids—rather than delaying peanuts until toddlerhood.
What the LEAP study proved about peanut introduction for baby
In 2015, Professor Gideon Lack and colleagues published the LEAP trial (Learning Early About Peanut Allergy, Du Toit et al., New England Journal of Medicine 2015). The randomised controlled trial followed 640 high-risk infants (aged 4 to 11 months with severe eczema, egg allergy, or both) through to age five.
Half of the families were instructed to avoid peanut protein completely; the other half fed their infants at least 6 grams of peanut protein per week (roughly 3 heaped teaspoons of peanut butter per week, divided across 3 or more meals). At age five, 17.2% of the avoidance group had developed peanut allergy, compared with just 3.2% of the early consumption group—an 81% relative reduction in peanut allergy.
According to the NIAID Addendum Guidelines, the NHS, and ASCIA:
- Standard-risk infants (no eczema or mild eczema, no food allergies): Introduce smooth, thinned peanut butter around 6 months of age at home alongside other early solids.
- Higher-risk infants (severe eczema or an existing egg allergy): Speak with your GP, health visitor, or paediatric allergist around 4 to 6 months to plan introduction (which is still strongly recommended early, sometimes following an allergy check).
The choking rule: How to thin peanut butter for baby
Whole peanuts, chopped peanuts, and crunchy peanut butter are strict choking hazards and must never be given to children under age five. Even smooth peanut butter straight from the jar is a choking hazard for infants because its thick, sticky viscosity can adhere to the roof of the mouth and block the pharynx.
Before serving, always prepare a thinned mixture using one of these four methods:
| Preparation Method | Exact Ratio (6m+ Starter) | Best For |
|---|---|---|
| 1. Warm Water, Breast Milk, or Formula Slurry | Mix 1/2 tsp smooth peanut butter with 1 to 2 tsp warm boiled water, breast milk, or formula until completely smooth and runny | First allergen test on a spoon (zero other new ingredients) |
| 2. Swirled into Porridge or Fruit Purée | Stir 1/2 to 1 tsp smooth peanut butter into 2 tbsp warm oat porridge, apple purée, or sweet potato mash | Spoon-feeding or pre-loaded spoons |
| 3. Whisked into Plain Yogurt | Whisk 1 tsp smooth peanut butter into 2 tbsp plain whole-milk yogurt (only after dairy is already tolerated) | Quick breakfast maintenance dose |
| 4. Peanut Flour / Defatted Peanut Powder | Stir 1/2 tsp 100% pure peanut powder into purée, porridge, or lentil dahl | Easy mixing without sticky texture |
Step-by-step peanut introduction baby protocol (Day 1 to Day 3)
Follow this clinical home protocol when your baby is completely well (no fever, cold, or active eczema flare) and during a morning or midday meal so you can observe them awake for at least two hours:
- Step 1 — Prepare the thinned puree: Whisk 1/2 teaspoon of 100% smooth peanut butter with 1 to 2 teaspoons of warm water, breast milk, or a already-tolerated vegetable/fruit purée until smooth.
- Step 2 — The initial tip-of-spoon taste: Offer a small dab (about 1/8 to 1/4 teaspoon) on the tip of an infant spoon. Do not rub peanut butter onto your baby's cheek or skin to "test" for a rash—skin contact can cause local redness or sensitisation without building gut tolerance. Put the food directly in the mouth.
- Step 3 — Wait 10 to 15 minutes: Watch your baby closely while continuing normal calm play in the high chair.
- Step 4 — Finish the starter portion: If no symptoms appear after 15 minutes, offer the remainder of the 1/2-teaspoon mixture at your baby's normal pace and observe for 2 hours.
- Step 5 — Days 2 and 3: Repeat the exposure over the next two days, increasing to 1 full teaspoon of smooth peanut butter thinned into porridge or mash.
How to recognise an allergic reaction
Most peanut reactions are IgE-mediated and appear within minutes (and almost always within 2 hours) of ingestion:
- Mild to moderate symptoms: New hives (red, raised welts) around the mouth, face, or body; swelling of the lips, face, or eyelids; sudden vomiting or diarrhoea. Stop feeding immediately and contact your GP or non-emergency medical line for advice.
- Severe symptoms (Anaphylaxis — Call 999 / 911 / 112 immediately): Persistent coughing, wheezing, noisy breathing, hoarse cry, swelling of the tongue, pale or floppy appearance, or extreme lethargy after eating.
Maintaining tolerance: Keep peanut in the weekly rotation
In the LEAP trial, protection came from sustained weekly intake, not a one-time taste. Once your baby has tolerated peanut butter across three exposures, serve thinned peanut butter, peanut-oat fingers, or peanut satay sauce at least 2 to 3 times every week (aiming for roughly 2 teaspoons of peanut butter per week total). You can log each exposure and set maintenance reminders in the 100 Bites baby allergen tracker.
Feeding your baby shouldn't feel like an exam. 100 Bites gives you three fresh ideas every morning, tracks all nine allergen groups, and remembers what happened so you do not have to keep a mental spreadsheet at 7am.
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