Nut Allergy in Babies: Early Introduction, Signs and What to Do

Peanut allergy is one of the most common food allergies in children in the UK, and one of the least likely to be outgrown. For many years, parents were told to avoid introducing peanuts early — particularly if there was a family history of allergy. That guidance changed dramatically following the results of the LEAP study, and the current evidence points firmly in the opposite direction: early introduction protects rather than risks.

The LEAP Study: What It Found

The Learning Early About Peanut Allergy (LEAP) study, published in 2015, followed over 600 high-risk infants (those with severe eczema, egg allergy, or both) and randomised them to either avoid peanuts until age five or consume them regularly from four to eleven months.

The results were striking. Children who consumed peanut protein regularly from early infancy had an 81% lower rate of peanut allergy at age five compared to those who avoided it. Follow-up studies showed that the protection persisted even after regular consumption stopped.

This study fundamentally changed international guidelines. The UK's Scientific Advisory Committee on Nutrition (SACN) and allergy societies now recommend that, for most babies, peanuts can be introduced as part of normal weaning, and that early introduction is actively encouraged.

Who Should Introduce Peanuts Under Medical Supervision?

The guidance differs depending on your baby's risk level.

Low to moderate risk (no eczema, or mild eczema): You can introduce peanut products at home as part of normal weaning from around six months. No allergy testing is needed first.

High risk (severe eczema and/or existing egg allergy): The NHS recommends speaking to your GP or allergy specialist before introducing peanuts at home. Your baby may be offered a supervised introduction in clinic, or a skin prick or blood test to guide the approach. This is not because introduction should be avoided, but because the small number of babies who are already sensitised need extra care.

If you are unsure which category your baby falls into, ask your health visitor or GP.

How to Introduce Peanuts Safely at Home

Age: Weaning generally starts at around six months (not before 17 weeks). Peanuts can be introduced as part of the first foods.

Form: Whole peanuts are a choking hazard and must never be given to children under five. Instead, use:

• Smooth peanut butter (thinned with a little breast milk, formula, or water, or spread thinly on a piece of toast)
• Peanut puffs designed for babies (such as Bamba snacks, which were used in the LEAP study)
• Peanut powder mixed into purees or porridge

First introduction: Choose a time when your baby is well and not due an immunisation that day. Give a small amount in the morning so you can observe for a couple of hours.

Frequency: The LEAP study used three or more servings per week. Regular consumption appears to maintain tolerance better than occasional exposure.

Signs of an Allergic Reaction to Watch For

An IgE-mediated allergic reaction typically occurs within minutes to two hours of eating the allergen. Symptoms range from mild to severe:

Mild to moderate:

• Hives (raised, itchy red welts on the skin)
• Redness or swelling around the mouth
• Itching of the eyes, nose, or mouth
• Vomiting

Severe (anaphylaxis) — requires emergency action:

• Swelling of the lips, tongue, or throat
• Difficulty breathing or noisy breathing
• Hoarse cry or voice
• Pallor, floppiness, or loss of consciousness
• Sudden drop in energy or alertness

What to Do If a Reaction Occurs

Mild reaction: Stop feeding, give a non-drowsy antihistamine appropriate for your baby's age and weight (always check the product is suitable — some antihistamines are not licensed for infants under one year), and call your GP or NHS 111 for advice.

Severe reaction / anaphylaxis: Call 999 immediately. If your baby has been prescribed an adrenaline auto-injector (EpiPen or Jext), use it without delay. Lay your baby flat (or slightly reclined if breathing is difficult) and wait for the ambulance. Even if symptoms seem to resolve, your baby must be seen in hospital — anaphylaxis can have a biphasic response where symptoms return hours later.

After a Reaction

If your baby has a clear allergic reaction to peanuts, contact your GP the same day or the following morning. They will typically:

• Prescribe an adrenaline auto-injector if not already prescribed
• Refer to a paediatric allergy clinic for formal testing and assessment
• Advise on avoiding peanuts and cross-contamination until the appointment

Tree Nuts: A Note on Cross-Reactivity

Peanuts are actually a legume rather than a tree nut, but many people with peanut allergy are also allergic to one or more tree nuts (such as cashews, walnuts, almonds, or hazelnuts). Cross-reactivity between tree nuts is also common. If your baby has a confirmed peanut allergy, the allergy specialist will advise on which tree nuts to introduce and how.

Ongoing Management

Peanut allergy is managed primarily by strict avoidance. For older children and adults, oral immunotherapy (OIT) — a controlled programme of gradually increasing peanut exposure under medical supervision — is now available on the NHS in some areas and can significantly reduce the severity of reactions. This is not a cure, but it raises the threshold dose that triggers a reaction, providing important day-to-day protection.

For now, with a baby newly diagnosed, the priorities are clear labelling awareness, an up-to-date allergy action plan, and ensuring all regular carers and nursery staff know what to do in an emergency.