Heterotheca Inuloides Flower Extract

Heterotheca inuloides (Mexican arnica) flower extract is used as a botanical soothing/anti-inflammatory agent, but like many Asteraceae (Compositae) extracts it carries a meaningful risk of irritant or allergic contact dermatitis, especially in eczema-prone or highly reactive patients. Reported sensitization to sesquiterpene lactones and related constituents, plus variability in extract composition, makes reactions plausible even at typical low leave-on concentrations. Given the potential for delayed sensitization and real-world cumulative exposure in routines, I score it as moderate and patch-testing is prudent for sensitive skin. Safety Notes: In commercial skincare, Heterotheca inuloides (Mexican arnica) flower extract is most often used as a minor soothing/antioxidant botanical in leave-on products (creams, serums, after-sun, post-procedure calming) at trace-to-low levels around 0.001–0.1%, consistent with typical supplier recommended use levels for standardized extracts. Higher-strength OTC products marketed for redness relief, bruising/irritation support, or botanical “active” positioning (often gels/balms/spot products) can use it at ~1–5% when formulated as a glycerin/propylene glycol extract or concentrated botanical solution; this upper end reflects observed consumer-available specialty formulations rather than typical mass-market usage.