How to Introduce Allergenic Foods to a Baby

The short answer

Once a baby is developmentally ready for solid food, current CDC and NHS guidance does not tell families to delay foods simply because they commonly cause allergy. Introduce one suitable food at a time, in a texture the baby can safely manage, and keep a clear record of what was offered. A baby with severe or persistent eczema, an existing food allergy, or a previous immediate reaction needs an individual plan from their clinician before peanut or other highly allergenic foods are introduced.

Call emergency services now for these signs

The current NHS food-allergy page places all seven signs below under its highest urgency tier, "Call 999." This is UK routing. Call 999 if:

• The lips, mouth, throat or tongue suddenly become swollen.
• Breathing becomes very fast or difficult. The person may be very wheezy or feel as though they are choking or gasping.
• The throat feels tight or swallowing is difficult.
• The skin, tongue or lips turn blue, grey or pale. On black or brown skin, the NHS says this may be easier to see on the palms or soles.
• The person suddenly becomes very confused, drowsy or dizzy.
• Someone faints and cannot be woken.
• A child is limp, floppy or not responding as usual. The NHS examples include the head falling sideways, backwards or forwards, or difficulty lifting the head or focusing on a face.

The NHS says a swollen, raised or itchy rash may also be present. These signs can indicate a serious allergic reaction that needs immediate hospital treatment. Do not drive yourself to A&E. The 999 call handler will tell you what to do. If a child has a prescribed adrenaline auto-injector or nasal spray and an allergy action plan, follow that plan and the device instructions immediately, then call 999 even if the child appears better. Elsewhere, use the local emergency number and the emergency plan your child's clinician provided.

If you are worried about your baby right now, you do not need a reason that satisfies anyone. Call your pediatrician, your local out-of-hours service, or your emergency number. Trusting your instinct is the correct response.

This page explains general guidance. It cannot decide whether a particular baby is ready for solid food, at increased allergy risk, or having an allergic reaction. Those decisions belong to the pediatrician, GP, health visitor or allergy specialist who knows the baby's medical and feeding history and can examine the baby.

Start with solid-food readiness, not an allergen calendar

The CDC says children can begin eating solid foods at about 6 months and that introducing foods before 4 months is not recommended. It looks for developmental abilities such as sitting alone or with support, controlling the head and neck, opening the mouth for food, and swallowing rather than pushing food back out. The NHS frames solid-food introduction from around 6 months.

Those age phrases are deliberately not a home clearance test. A premature baby, or a baby with a health, growth, swallowing or developmental concern, needs advice from the clinician who knows that history. Allergenic food is still solid food: the baby must be able to manage the form in which it is served.

Breast milk or infant formula remains central when solids begin. This article is not a reason to reduce milk feeds, change formula, or make a feeding schedule. Those choices belong with the baby's clinician.

Which babies need a clinician-led plan first?

Two current authorities describe overlapping but not identical risk routes.

The CDC tells caregivers of a child with severe eczema or an egg allergy to speak with the child's doctor or nurse about when and how to introduce peanut foods safely. The American Academy of Pediatrics says a baby who has or had severe, persistent eczema or an immediate allergic reaction to any food, especially egg, is at high risk for peanut allergy and should have the timing and method decided with the pediatrician first.

The NHS casts a wider UK advice net. It says to talk to a GP or health visitor before introduction if the baby has a diagnosed food allergy or eczema, or if there is a family history of food allergy, eczema, asthma or hay fever.

These are referral rules, not a scoring system to combine at home. Do not arrange a first peanut exposure, repeat a food that caused an immediate reaction, or order allergy testing from this article. Testing and any supervised introduction are clinician decisions.

How do you introduce one allergenic food clearly?

First choose the national guidance that applies to your baby. The details differ:

• The CDC says to offer one single-ingredient food at a time at first and wait 3 to 5 days between each new food. It says potentially allergenic foods can be introduced when other foods are introduced.
• The AAP advises one new food at a time and at least a day before another. If diarrhoea, rash or vomiting occurs, it says to stop the new food and consult the child's pediatrician.
• The NHS says that, from around 6 months, foods that can trigger allergy should be introduced one at a time so a reaction can be noticed. It does not give a between-food interval on that page.

Do not average those intervals into a new universal rule. Follow the guidance for your country or the plan your baby's clinician gives you.

Keep the first serving simple enough that you know which new food was offered. That does not mean every meal must have one ingredient forever. It means avoiding a mixture of several foods the baby has never eaten when the purpose is to observe one introduction.

Which foods count as common allergens?

The CDC's examples are eggs, shellfish, nut butters and wheat. The AAP also names egg, peanut and other nut products, dairy, wheat, sesame, soy, fish and shellfish. The NHS list includes:

• Eggs.
• Nuts and peanuts.
• Cows' milk.
• Gluten-containing grains including wheat, barley and rye.
• Beans, lentils and peas.
• Seeds, especially sesame.
• Soya.
• Shellfish.
• Fish.
• Celery.
• Mustard.
• Sulphur dioxide, which can occur in dried fruit and fruit juice.

The lists reflect different national contexts and are not identical. They also do not mean a baby is allergic to a food before eating it. A clinician diagnoses a food allergy from the history, examination and, when indicated, testing.

Use a form the baby can manage safely

Allergy guidance does not cancel choking guidance. The CDC says food should be prepared to the right shape, size and texture for the child's development. It says to avoid small, sticky or hard foods that are difficult to chew and swallow, have the child sit upright in a high chair or other safe place, and watch continuously while the child eats.

Whole or chopped nuts and seeds are on the CDC choking-hazard list. So are chunks or spoonfuls of nut or seed butter. The NHS says nuts and peanuts should be served finely ground or as nut butters and seeds should be finely ground. Use those statements together carefully: a thick spoonful of nut butter is not an infant-safe form merely because nut butter appears on an allergen list.

The NHS also says not to serve shellfish raw or lightly cooked. Its egg note is specific to UK Lion-marked eggs: eggs without a red lion stamp should not be eaten raw or lightly cooked. Outside that system, follow the egg-safety guidance for your country. This page does not turn a food-safety exception from one country into a global rule.

If you are uncertain about texture, ask the baby's clinician what form matches the baby's current ability. Arrange appropriate infant first-aid training before it is needed. This article does not replace hands-on choking-response training.

What might an allergic reaction look like?

The NHS baby-allergy page says reactions usually happen within a few minutes of trying a new food but can take up to 2 hours. It also says some allergies, including cows' milk allergy, can take up to 3 days to produce symptoms. Those are source-specific ranges, not a stopwatch that rules allergy in or out.

Its possible symptoms include:

• Swollen lips or face.
• Red, itchy or watery eyes.
• Wheezing and coughing.
• A red, itchy rash.
• Worsening eczema.
• Feeling or being sick.
• Tummy pain, diarrhoea or constipation.
• Sneezing.
• A runny or blocked nose.
• Worsening asthma symptoms.

That list does not diagnose the cause. A rash, vomiting or unsettled behaviour can have more than one explanation. Stop the newly introduced food and contact the baby's clinician if you think a reaction occurred. Use the emergency signs above immediately rather than waiting to see whether a severe reaction settles.

What should you record for the clinician?

Write down the food and ingredients, how it was prepared, when the baby ate it, when each sign began, how severe it appeared, how long it lasted and what was done. The AAP's food-allergy page says those are the kinds of details a doctor uses when evaluating a suspected reaction.

Keep packaging or an ingredient label with the notes if it is available. After a suspected reaction, follow the AAP direction to stop using the new food and consult the child's pediatrician. This article does not tell you to repeat the food at home to prove which ingredient was responsible.

Skin-prick and blood tests can help narrow possible causes, but the AAP notes that they are not always reliable on their own: a child can have a positive test without symptoms after eating, or a negative test and still have an allergy. Interpretation belongs to a pediatrician or allergy specialist.

What happens after a food is tolerated?

The NHS says that once an allergenic food has been introduced and tolerated, it should become part of the baby's usual diet to minimise allergy risk. The AAP likewise describes continued, routine inclusion in developmentally appropriate portions.

Neither statement supplies one schedule for every baby. Continue the food in a form the baby can safely manage and within the feeding guidance that applies to your family. If keeping it in the diet raises a practical or medical question, ask the baby's clinician rather than inventing a frequency from a general article.

For a child with a diagnosed allergy, follow the allergy action plan and avoidance instructions from the specialist. Do not use the general introduction steps above to test whether the allergy has gone away.

A simple plan to take to the appointment

Before the first allergen introduction, note whether the baby is ready for solids, whether there is eczema, any previous immediate food reaction, any diagnosed allergy and the relevant family history. Ask which national guidance the clinician wants you to follow, whether peanut needs an individual plan, which forms suit the baby's development, what signs require a same-day call and what requires emergency action.

That leaves the medical decisions with the person who can assess the baby. It also leaves you with a practical job: one identifiable food, an appropriate texture, close supervision, a clear record and no pressure to prove anything in one sitting.

Browse the site's other source-led feeding references in the feeding guides.

Sources

• When, What, and How to Introduce Solid Foods - CDC - US readiness, one-food introduction, 3-to-5-day interval, allergen timing and high-risk peanut referral. Updated 14 April 2026.
• Choking Hazards - CDC - preparation, upright seating, supervision, nuts and thick nut-butter hazards. Updated 11 March 2026.
• When to Introduce Egg, Peanut Butter and Other Common Food Allergens to a Baby - HealthyChildren.org, AAP - current AAP timing, risk route, continued inclusion and infant-safe forms. Updated 12 June 2025.
• Food Allergies in Children - HealthyChildren.org, AAP - reaction categories, clinician history, testing limits and allergy-plan ownership.
• Your baby's first solid foods - NHS - UK readiness, premature-baby referral, continuing milk feeds and food preparation. Reviewed 19 February 2026.
• Food allergies in babies and young children - NHS - UK introduction, food list, reaction timing and symptoms.
• Food allergy - NHS - complete current call-999 tier, emergency-device route and clinician diagnosis. Reviewed 20 August 2026.

Independent guidance, not medical advice. We do not diagnose or recommend treatments or doses. For any concern about your baby, contact your pediatrician or local emergency service.