Crotonic Acid

Crotonic acid is an unsaturated carboxylic acid that occurs naturally and serves as a precursor to several bioactive compounds. In skincare, crotonic acid itself is used sparingly, but derivatives of this molecule—most notably mupirocin (pseudomonic acid)—have established antimicrobial applications. The ingredient functions primarily as a masking agent and stabiliser in formulations.Crotonic acid derivatives, particularly mupirocin, are well-known in clinical dermatology and infection control. Mupirocin is extracted from the bacterium Pseudomonas fluorescens and works by inhibiting bacteria…

Crotonic acid derivatives such as mupirocin operate by inhibiting bacterial isoleucyl-tRNA synthetase, an enzyme essential for bacterial protein synthesis. This mechanism prevents bacteria from producing the proteins they need to survive and reproduce, effectively controlling microbial populations on the skin.In its role as a stabiliser, crotonic acid helps preserve the chemical stability of other actives and the overall formulation, extending shelf life and maintaining efficacy throughout the product's lifespan.

Crotonic acid is typically used at low concentrations in finished skincare products where it serves a stabilising or masking function rather than as a primary active. If using a product containing crotonic acid derivatives, follow the manufacturer's instructions. For clinical applications (such as mupirocin-based treatments for infection), use only under healthcare guidance.

Crotonic acid is generally recognised as safe in skincare formulations at typical concentrations. Mupirocin, the clinically significant derivative, is well-tolerated topically but should not be used excessively to avoid promoting bacterial resistance.