Polyester-5

Polyester-5 is an inert synthetic film-forming polymer used primarily in makeup (e.g., long-wear/transfer-resistant products) at low-to-moderate levels; it is not a biologically active ingredient and is generally non-sensitizing. Clinically, irritation is uncommon, but in highly reactive or eczematous skin it can contribute to stinging or dermatitis indirectly via occlusion/film effects or friction—so I do not score it as fully inert. Overall, it is very gentle for most users, with low but non-zero risk in compromised skin. Safety Notes: Polyester-5 is used in OTC cosmetics primarily as a film former/texture modifier (often in sunscreens, primers, and long-wear makeup), where it can appear at low levels (~0.1–1%) to improve feel, wear, and water resistance. In high-hold, high-resistance leave-on formulations (e.g., water-resistant sunscreen lotions/sprays, long-wear primers/foundations), it can be pushed into the mid-to-high single digits, with observed consumer products using up to ~10% depending on the polymer grade and overall film-former package. It is uncommon to see it used at meaningful levels in rinse-off products versus leave-on, where deposition/film formation is the objective.