Nothing New Under the Sun?: Sunflower Oil Shows No Cross‐Reactivity With Nickel or Compositae Allergens

Sunflower oil (Helianthus Annuus (Sunflower) Seed Oil, INCI) is a common emollient in personal care products. As a member of the Compositae plant family and a seed high in nickel content, its potential relevance for patients allergic to Compositae or nickel is of clinical interest. This study aimed to assess patch test reactivity to sunflower oil and examine potential sensitisation to these two allergens. We retrospectively reviewed 568 patients patch-tested with sunflower oil at our tertiary referral clinic in Minneapolis, MN, between October 2023 and November 2024. Testing was performed using 100% sunflower oil (La Tourangelle, Woodland, CA) in Finn Chambers (SmartPractice, Phoenix, AZ) applied to the upper back or thighs for 48 h. Readings were conducted on Day 2 and Day 4 or 7 using ICDRG criteria. The NACDG 2021–2022 standard series was tested concurrently, which included nickel sulfate 2.5% and 5% (pet.), Compositae mix 6% (pet.) and sesquiterpene lactone mix 0.1% (pet.) (Chemotechnique Diagnostics, Vellinge, Sweden). Zero reactions to sunflower oil were observed (0/568; 0%). In contrast, 122 patients (21.5%) reacted to nickel and 36 (6.3%) to Compositae-related allergens. No patients reacted to sunflower oil, including those positive to nickel or Compositae. Despite its widespread use, sunflower oil has rarely been studied as a potential allergen. Our data show no contact sensitization in over 500 patients, including those allergic to nickel or Compositae, suggesting it is not a clinically relevant allergen. Though sunflower is a member of the Compositae family, allergenic sesquiterpene lactones are typically confined to secretory plant structures like trichomes, found on leaves and flowers—not seeds [1, 2]. Solvent extracts of seeds may show trace allergen presence, but oil pressed from dehulled seeds contains only minute quantities [3, 4]. Additionally, sunflower seeds rank high among nickel-containing foods, which may prompt concern for nickel-allergic patients [5]. However, refined sunflower oil contains undetectable nickel levels even when derived from plants irrigated with nickel-contaminated water [6, 7]. Refining removes metal residues to improve stability and product quality [8]. Only one case report has implicated sunflower oil in contact allergy, and the case involved a lip balm with multiple consituents [9]. Our findings support its overall safety for topical use, even among populations sensitive to related allergens. This study is limited by its single-centre design and use of only one commercially available sunflower oil. Broader testing across formulations would further support these findings. Sarah Karels: conceptualization, investigation, writing – original draft, methodology, formal analysis, data curation. Sara Hylwa: data curation. Solvieg Ophaug: data curation. Katherine Lee: data curation. Anne Neeley: writing – review and editing, validation, supervision, data curation. Sara Hylwa is a paid speaker for the Contact Dermatitis Institute. This study was determined to be exempt from review by the HealthPartners Institute IRB. The authors declare no conflicts of interest.