Trisiloxane

Trisiloxane is a volatile silicone used as a slip/feel and spreading agent, typically at low percentages in leave-on products; it is chemically inert, non-water-soluble, and not an active that alters skin pH or barrier function. Available safety and patch-test data for similar low–molecular weight silicones suggest a low rate of irritation/sensitization, with occasional stinging or dryness reported in very reactive or barrier-impaired skin, especially when combined with other solvents or actives. Given rare but possible intolerance in compromised eczema skin and the need to avoid underestimating risk, it fits best as “very gentle” rather than fully inert. Safety Notes: In consumer skincare/haircare, trisiloxane is most often used as a low-level slip/spread enhancer in leave-on serums, sunscreens, primers, and some rinse-off cleansers at ~0.05–1%. Higher-strength OTC products (especially silicone-feel primers, blurring serums, and some hair anti-frizz/shine products) can use trisiloxane as a significant part of the volatile silicone phase, with real-world commercial levels commonly in the ~5–15% range and occasionally approaching ~20% in specialized high-slip, fast-dry formats. There is no specific EU/FDA concentration cap for trisiloxane in cosmetics; practical limits are driven by sensorial goals, volatility, and compatibility with other oils/film formers.