What is the primary mechanism of action of alcohol-based hand sanitizers?

Alcohol (ethanol or isopropanol) at concentrations of 60-95% kills microorganisms primarily by denaturing and coagulating proteins, including cell membrane proteins and enzymes. This disrupts cellular structure and function, causing cell death. Alcohol also dissolves lipid membranes of enveloped viruses. Important limitations: alcohol does not kill bacterial spores, Clostridioides difficile spores, or norovirus effectively. Alcohol does not permanently eliminate skin bacteria; transient flora are killed, but resident flora quickly repopulate.