Quick answer: Current guidance: introduce the major allergens early (from 6 months) and continue offering them regularly. Early introduction significantly reduces allergy risk. The top 9 allergens are: milk, eggs, peanuts, tree nuts, fish, shellfish, wheat, soy, and sesame.
The science behind early introduction
The LEAP (Learning Early About Peanut Allergy) trial, published in the New England Journal of Medicine in 2015, changed clinical practice globally. High-risk infants given peanut products from 4–11 months showed an 86% reduction in peanut allergy development compared to those who avoided peanuts until age 5. Follow-up trials (LEAP-On) showed the protection persisted even after stopping regular peanut consumption. The immune tolerance hypothesis: early, regular exposure teaches the immune system to recognise the protein as food rather than a threat. This principle has since been extended to other allergens, and current NICE guidance, AAP recommendations, and the NHS’s Start4Life advice all reflect the early introduction approach.
How to introduce each allergen safely
Introduce allergens when your baby is well (not in the middle of a viral illness or established eczema flare). Introduce one new allergen at a time with 2–3 days between each new introduction — this allows you to identify a reaction if one occurs without confusion about the cause. Offer in the morning at home (not before nursery, a long car journey, or any time you wouldn’t be able to observe for 2 hours). Start with a small amount: quarter teaspoon of smooth peanut butter thinned with milk or water; a small piece of well-scrambled egg. If tolerated, serve the same allergen again the same day or the following day, increasing the amount. Once established: aim to include each allergen in the diet 2–3 times per week — sustained regular exposure is what maintains tolerance.
Signs of a reaction and what to do
Mild reactions (within 2 hours of eating): hives (raised, red, itchy skin rash), swelling of the lips or face, vomiting. These warrant a call to 111 (UK) or your doctor, and the allergen should not be reoffered until assessed. Anaphylaxis (within minutes): throat swelling, difficulty breathing, wheezing, sudden pallor or limpness, loss of consciousness. This is an emergency — call 911 immediately. If your baby has been prescribed an EpiPen due to prior reaction, use it. Signs that are NOT allergic reactions: a little redness around the mouth from contact with acidic food (strawberries, tomatoes), or slight redness of the skin without other symptoms.
High-risk babies: when to see a specialist first
Babies at high risk of peanut allergy (severe eczema and/or egg allergy before 6 months) should be assessed by an allergist before home peanut introduction. The LEAP protocol found high-risk babies still benefit from early introduction — but testing first establishes whether supervised introduction is needed. If your baby has significant eczema, discuss allergen introduction with your doctor or pediatrician before starting.
After a reaction: re-introduction
Never re-introduce an allergen at home after a confirmed reaction without doctor or allergist guidance. Even mild reactions require assessment before re-challenge. For babies who’ve had anaphylaxis: specialist allergy assessment is essential and home re-introduction is not appropriate.
Frequently Asked Questions
Should I introduce peanuts even if there’s no family history of peanut allergy?
Yes — current guidance recommends early introduction for all babies, not just high-risk ones. Family history of peanut allergy doesn’t need to be present for the benefit to apply. Most peanut allergies develop in children without a family history.
Can I give whole peanuts to a baby?
No — whole nuts, nut pieces, and thick nut butters are choking hazards until age 5. Use smooth peanut butter thinned to a loose consistency, peanut puffs (products like Bamba or equivalent), or ground nuts mixed into food.
What if my baby reacts to multiple allergens?
Multiple allergen sensitivity in infancy can indicate a condition called food protein-induced enterocolitis syndrome (FPIES) or a broader atopic tendency. It warrants doctor referral and possibly allergy specialist assessment to map the sensitivity accurately and advise on safe introduction sequencing.
Related Reading
- 6 month old baby: starting solids – a complete first-foods guide
- Baby-led weaning vs purees: which approach is right for your family
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