The advice on when and how to introduce allergenic foods has reversed in the past decade. The "delay until 12 months, no peanut until 3 years" guidance some parents grew up with is now outdated and almost certainly contributed to the rise in childhood food allergy. The current advice — introduce common allergens around 6 months, alongside other first foods, and keep offering them — is grounded in strong randomised trial evidence and is endorsed by the NHS, BSACI, NICE, and the AAAAI internationally.
Knowing how to do this safely matters most for families with eczema in the baby or food allergy in close family, but the approach is broadly the same for everyone.
Healthbooq supports parents with current, evidence-based guidance on introducing solid foods, including the allergen introduction approach recommended by NICE and BSACI for infants at standard and elevated allergy risk.
How Guidance Has Changed
Until the mid-2000s, UK and international guidance advised delaying highly allergenic foods — particularly peanut and egg — to 12 months, 2 years, or 3 years. The reasoning was that delaying exposure would allow the gut and immune system to mature and reduce allergy. The 2015 LEAP trial (Learning Early About Peanut Allergy), published in the New England Journal of Medicine, showed the opposite. In high-risk infants (severe eczema or egg allergy), regular peanut consumption from 4-11 months reduced peanut allergy at age 5 by around 80% compared with avoidance. The EAT trial added similar evidence across multiple allergens including egg.
NHS, NICE, BSACI, and AAAAI guidance now recommends introducing allergens at the start of weaning, around 6 months (not before 4 months), rather than delaying.
The Fourteen Major Allergens
UK food labelling law identifies fourteen major allergens. The ones most relevant for infants are: peanuts, tree nuts (almonds, cashews, walnuts, pecans, hazelnuts), hen's egg, cow's milk, wheat, fish, shellfish, sesame, and soya. The vast majority of childhood food allergies involve peanut, milk, egg, and wheat.
The Standard Approach: Introducing at Home
For most babies — including those without eczema or family history of allergy — allergens go in at home alongside other first foods. The approach is simple: introduce one allergen at a time, with a small amount first, and wait 2-3 days before introducing the next new allergen so that if a reaction does happen you can identify the responsible food.
Practical forms by age 6-7 months:
- Peanut: smooth peanut butter (around half a teaspoon to start), thinned with a little warm water, breastmilk, or formula and stirred into purée or porridge. Never whole peanuts or chunks of peanut butter — both are choking hazards under 5.
- Egg: well-cooked. Scrambled, hard-boiled and mashed, or a strip of thin omelette. Avoid raw or runny egg.
- Cow's milk: in cooked dishes (cheese, yoghurt, butter, milk in pancakes). Not as a main drink before 12 months — it is too low in iron.
- Wheat: baby porridge, pasta, soft toast fingers.
- Sesame: smooth tahini stirred into purée or yoghurt.
- Fish: well-cooked white fish, mashed and bone-checked.
Offer the food when your baby is well, at the start of a meal (so the rest of the meal is still ahead and you can stop if needed), during the day so you can watch for two hours after. A small redness around the mouth where food has touched skin is common and usually not a true reaction — it tends to settle within 15-20 minutes and does not require medical attention unless it spreads or other symptoms appear.
Signs of Allergic Reaction
Mild (discuss with GP, do not require emergency treatment): localised redness or hives on skin where food touched, mild watery eyes or runny nose, single episode of mild vomiting after eating.
Moderate to severe — call 999 immediately: swelling of face, lips, or tongue; widespread hives across the body; persistent vomiting plus skin symptoms; wheeze, noisy breathing, or breathing difficulty; sudden floppiness, pale clammy skin, or unusual drowsiness; loss of consciousness. These features signal anaphylaxis.
Higher-Risk Infants
Babies with severe eczema — eczema needing regular prescription topical steroids, or covering significant body area — are at substantially higher baseline risk of food allergy. BSACI guidance recommends specialist assessment, with skin prick testing or specific IgE testing, before introducing peanut and egg in this group. The risk of a reaction at first introduction is high enough that doing it at home without testing is not appropriate. Ask your GP for an urgent paediatric allergy referral.
The same applies to babies who already have a confirmed food allergy. Closely related foods (other tree nuts if peanut allergic, for example) should be introduced under specialist guidance, not at home.
Maintaining Exposure
Once an allergen is in safely, keep offering it. Current evidence suggests 2-3 servings per week is enough to maintain tolerance for foods like peanut and egg. Introducing a food once and then dropping it from the diet for months is associated with loss of tolerance and reactions on re-exposure. Build allergens into your child's regular weekly menu rather than treating them as a one-off test.
Key Takeaways
Current evidence supports introducing common allergens — peanut, egg, cow's milk, wheat, fish, sesame — at the start of weaning around 6 months, not delayed to 12 months or later as families were once told. The 2015 LEAP trial showed early peanut introduction in high-risk infants reduced peanut allergy by approximately 80% compared with avoidance. NHS, NICE, BSACI, and AAAAI now align on early introduction. Most babies, including those with mild-to-moderate eczema, can have allergens introduced at home one at a time. Babies with severe eczema or an existing food allergy should be assessed by a specialist before peanut and egg are introduced. Once an allergen is in safely, keep offering it 2-3 times a week — tolerance can be lost without regular exposure.
