Perfluorodecalin

Perfluorodecalin is an inert, non-polar perfluorocarbon used in skincare (often a few percent) for its oxygen-carrying/skin-conditioning properties, and it is generally reported as non-sensitizing with low irritation in patch testing. However, because it is a strong hydrophobe that can feel occlusive and may contribute to follicular congestion or stinging when used on severely barrier-compromised skin or under occlusion, I do not score it as fully inert for high-risk eczema populations. Safety Notes: In consumer skincare, perfluorodecalin is typically used as an oxygen-carrying/performance additive in leave-on serums, creams, and sheet-mask ampoules, where it often appears around 0.1–2% and can be present at trace levels (~0.05%) when used mainly for marketing or sensory support. High-strength OTC “oxygenating” ampoules and barrier-repair/after-procedure recovery products available to the public have been marketed with substantially higher loads of perfluorocarbons, with perfluorodecalin observed up to ~10% in specialized leave-on emulsions/fluorocarbon phases. It is uncommon in rinse-off products due to cost and limited benefit under short contact time; the practical upper end is constrained by phase behavior, sensory, and the need for suitable emulsification/solubilization systems rather than explicit FDA/EU cosmetic concentration caps.