Farnesol

Farnesol is a fragrance/deodorant component (often used at low concentrations) with well-documented sensitization potential; it is a recognized fragrance allergen in patch testing and can trigger allergic contact dermatitis in susceptible individuals. While many tolerate it, in eczema-prone or highly reactive skin even small amounts can provoke burning, redness, or delayed flares, and cumulative exposure from fragranced routines increases risk. Given its allergen profile and the need for avoidance in sensitive populations, it warrants a notable irritancy score. Safety Notes: In commercial skincare and personal-care products, farnesol is most often used as a fragrance component/deodorizing antimicrobial at very low levels (around 0.001–0.05%) in leave-on creams/lotions and rinse-off washes where it functions primarily for odor control and fragrance character. Higher-strength consumer OTC use is seen in deodorant/antiperspirant-style leave-on products and targeted “odor-control” body products, where totals around 0.1–0.3% are marketed; above this is uncommon in mainstream retail due to sensitization/allergen considerations and diminishing formulation benefit. Farnesol is an EU-designated fragrance allergen requiring declaration above 0.001% in leave-on and 0.01% in rinse-off products, which aligns with the low end commonly observed in fragranced products.