Urtica Dioica

Urtica dioica (stinging nettle) extracts are used as botanical soothing/sebum-balancing agents, but the plant contains histamine, formic acid, and other stinging constituents that can trigger irritant contact reactions and contact urticaria, especially in compromised barrier skin. While cosmetic extracts are typically processed and used at low percentages, clinical experience and patch-test reports show botanicals like nettle can still provoke flares in eczema-prone or highly reactive patients. Given the potential for immediate stinging/itch and unpredictable sensitization risk, I rate it as a moderate irritant where patch testing is prudent. Safety Notes: In commercial skincare, Urtica dioica (nettle) is most often used as an extract in leave-on toners/serums/creams at very low levels (often ~0.001–0.1%) as part of multi-botanical blends, with rinse-off shampoos/cleansers commonly around ~0.05–0.5%. The upper end is observed in consumer-available “high-botanical” masks, scalp treatments, and herbal creams using concentrated glycerin/propylene glycol extracts or reconstituted dry extracts, where nettle-derived material can reach ~5–10% while remaining within typical EU/FDA cosmetic use (no specific maximum set, but limited in practice by odor/color, irritation potential, and extract solvent system).