How to Introduce Allergens Safely to Babies

A small smear of smooth peanut butter can feel like a very big moment when you are feeding your baby for the first time. Knowing how to introduce allergens safely can replace some of that anxiety with a clear, sensible plan. For most babies, early introduction of common allergenic foods as part of weaning is encouraged, rather than avoiding them without a medical reason.

The aim is not to test your child at home or to rush through a long list of foods. It is to offer suitable forms of allergenic foods one at a time, when your baby is well and you can observe them afterwards. For children with eczema, a previous reaction or other risk factors, the right plan may need to be more individual.

When should babies start allergenic foods?

Allergenic foods can usually be introduced from around six months of age, once a baby is developmentally ready for solid food. Signs of readiness include being able to sit with support and hold their head steady, coordinate their eyes, hands and mouth to pick up food, and swallow rather than push food back out with their tongue.

There is no benefit in deliberately delaying foods such as peanut, egg, milk, wheat, sesame, fish or soya in babies who are ready to wean. In fact, introducing these foods during infancy may help reduce the chance of some food allergies developing. Breastfeeding can continue alongside weaning for as long as mother and baby wish.

Cow’s milk should not be used as a main drink before 12 months, but it can be included in food from around six months - for example, in yoghurt or a cooked sauce. Whole nuts must never be given to young children because of choking risk. The issue is the form of the food, not simply the ingredient.

How to introduce allergens safely at home

Choose a morning or early afternoon when your baby is well, alert and not due to go to nursery, travel or sleep shortly afterwards. Avoid introducing a new allergen when they have a fever, vomiting, diarrhoea or a significant eczema flare, as symptoms can be harder to interpret.

Start with a very small amount of one allergenic food. For peanut, this might be a tiny smear of smooth peanut butter thinned with warm water, breast milk or formula, or peanut powder mixed into a familiar puree. For egg, offer a small amount of well-cooked egg, such as mashed hard-boiled egg or a thoroughly cooked omelette. Never give sticky spoonfuls of nut butter, whole nuts, or raw or lightly cooked egg to a baby.

Wait around 10 minutes, watching your child closely. If they remain well, offer a little more. Continue to observe them for about two hours. Most immediate allergic reactions occur within minutes and usually within two hours of eating, although delayed symptoms can occur for other reasons and need careful interpretation.

If the food is tolerated, include it regularly in your baby’s diet. This does not need to mean a large daily portion. A suitable amount once or twice a week, as part of normal family meals, is often practical. Regular exposure matters more than making one successful introduction and then avoiding the food for months.

Which foods should be introduced?

The common food allergens are peanut, hen’s egg, cow’s milk, tree nuts, sesame, soya, wheat, fish, shellfish and lupin. These should be introduced in age-appropriate, safe textures alongside a varied diet containing fruit, vegetables and iron-rich foods.

Introduce one new allergenic food at a time. This makes it easier to identify the cause if your child reacts. Once a food has been tolerated on several occasions, you can move on to another. There is no need to leave days between every familiar food, but avoid giving several new allergens together on the first occasion.

Texture needs as much thought as ingredient choice. Fish should be carefully checked for bones and flaked. Sesame can be mixed as tahini into a puree or yoghurt. Tree nuts should be given only as finely ground nut powder or a smooth nut butter thinned appropriately. Shellfish is not an essential early weaning food, but if offered, it should be thoroughly cooked and served in a soft, safe texture.

Babies who need advice before allergen introduction

Some children should not have a first introduction to a suspected allergen without medical advice. This includes any baby who has already had an immediate reaction after eating a food, such as hives, swelling, repetitive vomiting, coughing, wheeze or sudden lethargy.

Babies with severe or difficult-to-control eczema are also at higher risk of food allergy, particularly peanut and egg allergy. Eczema itself does not mean that a child must avoid allergenic foods, and unnecessary restriction can make family meals more stressful and nutritionally limited. However, early discussion with a clinician can help determine whether introduction at home is appropriate or whether testing and a supervised plan are needed.

A known food allergy, previous anaphylaxis, poor growth, multiple suspected food reactions or a complex medical history are further reasons for specialist assessment. A family history of allergy can raise understandable concern, but it does not automatically mean testing is required before weaning. The child’s own eczema, symptoms and feeding history are more informative.

At Children’s Allergy Cambridge, assessment considers the whole clinical picture. Skin prick testing and specific IgE blood tests can be helpful when interpreted alongside a detailed history, but a positive test alone does not prove that a child will react when they eat a food. Equally, broad screening tests without a clear history can lead to foods being avoided unnecessarily.

Recognising an allergic reaction

A mild reaction may involve a few hives, redness away from the mouth, itching, or swelling of the lips or face. A small area of redness where food has touched the skin is not always allergy, especially in babies with eczema, but widespread hives or symptoms that occur soon after eating require attention.

More concerning symptoms include persistent cough, wheeze, noisy breathing, a hoarse cry, difficulty breathing, swelling of the tongue or throat, repeated vomiting, marked paleness, floppiness or unusual drowsiness. These can indicate anaphylaxis, a serious allergic reaction.

If your child has breathing difficulty, becomes floppy or unusually sleepy, has persistent vomiting with other allergic symptoms, or you are seriously concerned, call 999 immediately. If they have been prescribed an adrenaline auto-injector, use it without delay according to their emergency plan, then call 999. Do not drive them to hospital yourself if anaphylaxis is suspected.

For a mild but clear reaction, stop offering the food and seek medical advice the same day. Take photographs of visible symptoms and make a note of the food, amount eaten, timing and any treatment given. This information is often more useful than trying the food again at home.

Avoiding common pitfalls

The safest approach is calm and planned, not overly cautious or overly casual. Do not rub food on your baby’s skin as an allergy test. Skin contact can irritate eczema and does not show whether the food is safe to eat. Similarly, do not rely on internet allergy tests, hair analysis or commercially marketed intolerance panels. These can cause confusion and restrictive diets without providing a reliable diagnosis.

Try not to introduce a new allergen at a restaurant, on holiday or just before a busy nursery morning. Home is generally the easiest place to observe your child and respond calmly. It is also sensible for the adult feeding the baby to be familiar with the difference between a minor local irritation and symptoms that need urgent help.

If your child has eczema, keep their skin treatment consistent. Well-managed eczema supports the skin barrier and can make rashes easier to assess. Food allergy is not the cause of every eczema flare, and removing multiple foods without expert guidance may compromise nutrition while missing the real triggers.

A plan that fits your child

Introducing allergens is a normal part of weaning for many families, but it is not identical for every child. A baby with clear skin and no history of reactions may need only a careful home introduction. A baby with severe eczema or a concerning response to egg may need a tailored plan, targeted testing or, occasionally, a medically supervised food challenge.

If you are unsure, pause rather than guessing. A clear assessment can help you introduce foods with appropriate confidence, protect your child from genuine risk and avoid a diet that is more restricted than it needs to be. The goal is for food to become a safe, ordinary and enjoyable part of family life.