Tree Nut Allergy

Tree nut allergy is an IgE-mediated Food Allergy to nuts such as walnut, almond, cashew and hazelnut. It is more common in children with Atopic Dermatitis. Which “nuts” count varies by law. The US FDA added shea nut to its tree-nut labelling list in 2006, but UK/EU law does not include shea among its regulated nuts (FARRP 2018; Allergy Insight 2025). For toddlers with eczema, the question is whether nut-derived skin products could sensitise through broken skin, as peanut oil appeared to in ALSPAC (see Peanut Oil Sensitisation). Refined Shea Butter contains no detectable protein and is judged very low-risk.

Tree Nut Allergy [part-of] Food Allergy Atopic Dermatitis [relates] Tree Nut Allergy

Prevalence in young children with eczema. In the Australian HealthNuts cohort of 5,276 children, parent-reported tree nut allergy was only 0.1% at age 1, but just 18.5% of infants had eaten a tree nut by then. By age 6, 3.3% had challenge-confirmed tree nut allergy, and cashew was the most common (2.7%). Children who had both peanut and egg allergy at age 1 had the highest risk: 37% had tree nut allergy at age 6, compared with 27% with peanut allergy alone and 14% with egg allergy alone (McWilliam 2019). Eczema at age 1 is the strongest known risk factor for these infant food allergies (see Food Allergy). Worldwide, tree nut allergy affects 0.05–4.9% of people. Sensitisation rises with age, from 2% at 0–2 years to 47% at 14 years. In a Swedish cohort, eczema at age 2 predicted IgE to tree-nut storage proteins in young adulthood (Bager 2021, cited in Nutrients 2024 review). It is unknown whether feeding tree nuts early prevents tree nut allergy, as LEAP Trial showed for peanut (Nutrients 2024 review).

Atopic Dermatitis [precedes] Tree Nut Allergy Peanut Oil Sensitisation [relates] Tree Nut Allergy

Skin sensitisation through nut-containing products. The Dual-Allergen Exposure Hypothesis proposes that food proteins on inflamed skin sensitise, while the same foods eaten early build tolerance. The most cited nut-oil case is Almond Oil. A 5-month-old with AD developed almond contact dermatitis after 2 months of almond oil on the cheeks and buttocks. She had a positive patch test, a positive prick test and class 4 almond IgE, and had never eaten almond (Guillet & Guillet, Allerg Immunol (Paris), 2000). Almond is also one of the most common food allergens in children’s skincare. Over a third of 276 children’s products contained a food allergen, almond, wheat and soy were the most common, and “natural”/“ecological” products were significantly more likely to contain them (Adomaite 2020). Argan Oil applied to the skin has caused anaphylaxis (J Investig Allergol Clin Immunol 2021). No paediatric data were found for macadamia oil. Refined shea is the exception: it has no detectable protein, so it is unlikely to sensitise (FARRP 2018).

Almond Oil [causes] Tree Nut Allergy Argan Oil [triggers] Tree Nut Allergy Dual-Allergen Exposure Hypothesis [supports] Tree Nut Allergy Shea Butter [relates] Tree Nut Allergy

Practical advice. Do not put nut oils (sweet almond, argan, macadamia, cold-pressed or unrefined nut butters) on a toddler’s inflamed or broken skin. Check the INCI list of “natural” baby oils and balms for Prunus amygdalus dulcis (sweet almond) and Argania spinosa (argan). Guillet’s conclusion was that “the choice of an ointment for lesional skin is of importance”. Avoiding nut oils on the skin is not the same as avoiding nuts in the diet. Early dietary introduction of allergens is now advised for infants with eczema (see LEAP Trial), and decisions about eating nuts should be made with the child’s doctor.

Nut-based oils on eczematous skin

Peanut oil on inflamed infant skin was linked to peanut allergy (Lack 2003, OR 6.8), and almond oil sensitised a 5-month-old with AD who had never eaten almond (Guillet 2000). Avoid almond, argan, macadamia and other unrefined nut oils on a toddler with eczema. Choose plain, fragrance-free emollients without food-derived ingredients.

Connections

• Shea Butter — FDA tree-nut listing; refined shea protein-free, source: FARRP 2018
• Peanut Oil Sensitisation — skin route of nut sensitisation, source: Lack 2003
• Food Allergy — parent category, source: FARRP 2018
• Almond Oil — percutaneous almond sensitisation in AD infant, source: Guillet 2000
• Argan Oil — anaphylaxis after cutaneous argan oil, source: JIACI 2021
• Atopic Dermatitis — eczema predicts tree nut sensitisation, source: McWilliam 2019; Bager 2021
• Dual-Allergen Exposure Hypothesis — cutaneous route of food sensitisation, source: Guillet 2000; Adomaite 2020
• LEAP Trial — oral early introduction proven for peanut, unknown for tree nuts, source: Nutrients 2024 review
• Dupilumab — lowered tree-nut sIgE 70–82% in paediatric AD over one year, source: Nutrients 2024 review