Introducing allergens to your baby: when, how and why early helps
Twenty years ago parents were told to wait. Today the evidence points the other way, with one important exception.
Updated October 13, 2026 · sources checked October 13, 2026
In short
Common allergens such as egg, peanut, milk, wheat, fish and sesame can be introduced from around 6 months, one at a time, alongside other first foods. In the LEAP trial, high-risk babies who ate peanut regularly from infancy had far less peanut allergy at age 5 (1.9% versus 13.7%). Babies with severe eczema or egg allergy should see their doctor before peanut is introduced.
Why the advice changed
For years, families were told to delay peanut and egg. Two British trials changed the guidance:
| Trial | Who took part | What was tested | Main result |
|---|---|---|---|
| LEAP (Du Toit, NEJM 2015) | 640 babies aged 4 to under 11 months with severe eczema, egg allergy or both | Eating peanut regularly versus avoiding it until 5 years | Among babies with a negative skin test at the start, peanut allergy at 5 years: 1.9% with peanut versus 13.7% with avoidance |
| EAT (Perkin, NEJM 2016) | 1,303 exclusively breastfed 3-month-olds from the general population | Six allergens from 3 months versus exclusive breastfeeding to about 6 months | No significant difference overall (5.6% vs 7.1%); among families who managed to stick to the plan, less peanut and egg allergy |
The NHS now summarises the evidence plainly: delaying peanut and hen's egg beyond 6 to 12 months may increase the risk of developing an allergy to them.
Which babies need a doctor first
The 2017 US addendum guidelines from the NIAID expert panel sort babies into three groups:
| Your baby | What the guideline recommends | Where |
|---|---|---|
| Severe eczema, egg allergy, or both | Peanut foods at 4 to 6 months, after an allergy blood or skin-prick test arranged by the doctor | Home or clinic, depending on results |
| Mild to moderate eczema | Peanut foods at around 6 months | At home (supervision in a clinic optional) |
| No eczema and no food allergy | Peanut foods along with other age-appropriate solids | At home |
In the UK, the NHS adds family history: if your baby has a diagnosed food allergy or eczema, or there is a family history of food allergies, eczema, asthma or hay fever, talk to your GP or health visitor first.
The allergens to introduce
The NHS lists the foods that can trigger allergic reactions and that can be introduced from around 6 months, just like any other food:
- cow's milk (in cooking or mixed with food; not as a drink before 12 months)
- eggs (well cooked if not British Lion stamped)
- foods containing gluten: wheat, barley, rye
- peanuts and tree nuts, finely ground or as a smooth nut butter, never whole
- seeds, especially sesame, finely ground
- soya
- fish, and shellfish (never raw or lightly cooked)
- beans, lentils and peas; also celery, mustard and sulphur dioxide (in some dried fruit)
A calm method, step by step
- Pick a good moment. Your baby is well (no cold or eczema flare), it is morning or early afternoon, and you can watch them for the next couple of hours. The NHS notes reactions can take up to 2 hours to appear.
- One new allergen at a time, in a very small amount, as the NHS advises, mixed into a food your baby already eats.
- Make it baby-safe. Peanut: smooth peanut butter thinned with warm water, breast milk or formula, or stirred into porridge or puree. Never a spoonful of thick nut butter (a choking hazard), never whole nuts before age 5.
- Wait before the next new allergen. The CDC's general advice for new foods is 3 to 5 days between each one, which also makes any reaction easier to trace.
- Keep it going. Once tolerated, offer it regularly. In the EAT trial, eating around 2 g of peanut or egg-white protein a week was associated with less allergy to those foods.
Signs of a reaction
| Mild to moderate (call your pediatrician, GP or NHS 111) | Severe: anaphylaxis (call 911 / 999 now) |
|---|---|
| Red, itchy rash or hives | Swelling of lips, mouth, throat or tongue |
| Itchy, watery eyes; runny or blocked nose; sneezing | Fast or struggling breathing, wheezing, noisy breathing |
| Vomiting, diarrhoea, tummy pain | Difficulty swallowing, hoarse voice |
| Worsening eczema | Blue, grey or pale skin, lips or tongue |
| A child who is limp, floppy or not responding normally |
The left column comes from the NHS food allergy pages; the right column from the NHS anaphylaxis page, which says to call 999 if you think someone is having an anaphylactic reaction. In the US, call 911. If your child has been prescribed an adrenaline auto-injector, use it as instructed and still call.
Do not cut out a major food such as milk on your own suspicion. The NHS warns this can leave your child short of nutrients; ask your GP or health visitor, who may refer you to a dietitian.
Allergens and choking
Allergen foods are often choking foods too: whole nuts, chunks of nut butter, whole grapes. Before your first allergen meals, read the first foods size chart and the choking vs gagging guide, and plan your sequence with the solids calendar.
Questions parents ask
Should I avoid peanuts while pregnant or breastfeeding to protect my baby?
No. The NHS states that pregnant or breastfeeding mothers do not need to avoid foods that can trigger allergic reactions, including peanuts, unless they are allergic to them themselves.
How long after a new food can a reaction appear?
The NHS says reactions usually happen within minutes, but symptoms can take up to 2 hours to appear, and up to 3 days for some allergies such as cow's milk allergy.
Do I have to keep giving the allergen once introduced?
Yes, if it is tolerated. The NHS advises keeping these foods as part of your baby's usual diet to minimise the risk of allergy. One taste followed by months of nothing is not the goal.
My baby has eczema. Can I still introduce peanut at home?
It depends on severity. Under the 2017 NIAID guidelines, babies with mild to moderate eczema can have peanut foods at home around 6 months, while babies with severe eczema, egg allergy or both should be assessed by a doctor first, ideally between 4 and 6 months.
Sources
- NHS — Food allergies in babies and young children checked October 13, 2026
- NHS weaning guide — Introducing foods that could trigger an allergic reaction checked October 13, 2026
- Togias A et al. Addendum guidelines for the prevention of peanut allergy in the United States (NIAID expert panel). Ann Allergy Asthma Immunol 2017 (DOI 10.1016/j.anai.2016.10.004) checked October 13, 2026
- American Family Physician — Peanut Allergy Prevention, Guidelines from the NIAID (2017 summary) checked October 13, 2026
- Du Toit G et al. Randomized Trial of Peanut Consumption in Infants at Risk for Peanut Allergy (LEAP). N Engl J Med 2015 (DOI 10.1056/NEJMoa1414850) checked October 13, 2026
- Perkin MR et al. Randomized Trial of Introduction of Allergenic Foods in Breast-Fed Infants (EAT). N Engl J Med 2016 (DOI 10.1056/NEJMoa1514210) checked October 13, 2026
- CDC — When, What, and How to Introduce Solid Foods checked October 13, 2026
- NHS — Anaphylaxis checked October 13, 2026
Mamavela explains; it does not replace your midwife, doctor or pediatrician, who know your situation. If something worries you, call them. In an emergency, call 911 (US), 999 (UK) or 112.