Here’s the thing nobody really explains: hand sanitizer is designed to work on already-reasonably-clean skin. When your hands have visible dirt, grime, or grease on them, the sanitizer may not make proper contact with the germs underneath. It ends up trying to work through a layer of dirt instead of reaching your actual skin — which is why it’s much less effective.
Both the CDC and the FDA are clear about this: don’t use hand sanitizer if your hands are visibly dirty or greasy. Wash with soap and water instead. That’s the actual recommendation from both agencies.
And even when your hands aren’t dirty, sanitizer still has limits. The CDC notes it doesn’t get rid of all types of germs, and the alcohol content matters too — sanitizers need at least 60% alcohol to be effective at killing germs. Products with less alcohol may only slow germ growth rather than actually kill them.
So the move is pretty simple: if there’s visible dirt or grease, go find a sink. Save the sanitizer for when soap and water aren’t available and your hands are already reasonably clean — like after touching a door handle or a shared surface. That’s where it actually earns its job.