Tree nut allergy is one of the most common food allergies in children and one of the most likely to persist into adulthood. It can cause reactions ranging from mild oral symptoms to severe anaphylaxis. Many parents are confused about which nuts are tree nuts, whether their child needs to avoid all nuts, and how tree nut allergy relates to peanut allergy. This article answers the most common questions.

What Are Tree Nuts?

Tree nuts are nuts that grow on trees. The most common tree nuts that cause allergy in children in the UK are:

  • Cashew nut
  • Walnut
  • Almond
  • Hazelnut
  • Pistachio
  • Brazil nut
  • Pecan
  • Macadamia nut
  • Pine nut

Peanuts are not tree nuts — they are legumes (related to peas and beans). However, peanut allergy and tree nut allergy frequently co-exist, and children with peanut allergy are at higher risk of tree nut allergy.

Is Tree Nut Allergy the Same as Peanut Allergy?

No. Peanut allergy and tree nut allergy are separate conditions caused by different allergen proteins. However, they often co-exist — approximately 25–40% of children with peanut allergy also have a tree nut allergy. This is partly due to cross-reactivity (similar proteins in different nuts) and partly due to co-sensitisation (separate allergies that happen to occur together).

Component-resolved diagnostics (CRD) — available at Belfast Children's Allergy Clinic — can help identify which specific nut proteins a child is sensitised to, which helps predict the severity of reactions and guide management decisions.

Cross-Reactivity Between Tree Nuts

Some tree nuts are botanically related and share similar proteins, which means a child allergic to one may also react to another:

  • Cashew and pistachio are closely related and cross-reactivity is common
  • Walnut and pecan are related and cross-reactivity occurs
  • Almond and peach share proteins (both are in the Rosaceae family)
  • Hazelnut and birch pollen share proteins — hazelnut allergy in older children is often pollen-related (oral allergy syndrome) rather than a true food allergy

Not all children with one tree nut allergy need to avoid all tree nuts. Dr Anandarajan will assess which nuts your child is genuinely allergic to and advise on which to avoid.

Symptoms of Tree Nut Allergy

Symptoms of tree nut allergy typically occur within minutes to 2 hours of ingestion and can include:

  • Tingling or itching in the mouth (oral allergy syndrome)
  • Hives (urticaria) or skin flushing
  • Swelling of the lips, tongue or throat (angioedema)
  • Nausea, vomiting or abdominal pain
  • Runny nose, sneezing or watery eyes
  • Wheeze or difficulty breathing
  • Dizziness or collapse (anaphylaxis)

Allergy Testing for Tree Nut Allergy

Dr Anandarajan offers comprehensive allergy testing for tree nut allergy at Kingsbridge Private Hospital and Ulster Independent Clinic, Belfast. Testing includes:

  • Skin prick testing: Results available within 15–20 minutes at the appointment
  • Specific IgE blood tests: For individual tree nuts
  • Component-resolved diagnostics (CRD): To identify specific allergen proteins and predict reaction severity

Testing helps determine which nuts your child is genuinely allergic to, which they may be able to tolerate, and whether they are at risk of severe reactions.

Managing Tree Nut Allergy

Management of tree nut allergy involves:

  • Strict avoidance of the specific nuts your child is allergic to
  • Reading food labels carefully — tree nuts must be declared on pre-packed food labels in the UK
  • Carrying an adrenaline auto-injector (EpiPen or Jext) if prescribed
  • Having a written anaphylaxis action plan
  • Informing school, nursery and carers

Book an Appointment

If your child has had a reaction to a tree nut, or if you are concerned about tree nut allergy, Dr Anandarajan can provide comprehensive allergy testing and a personalised management plan. Call 028 9066 7878 or book online at kph.fyi/Book-MAnandarajan. No GP referral is required.