Unless you use a straight razor that can be sharpened and reused for years, you'll need to replace your razor's blades when they begin to dull or rust. A dull blade won't cut or glide evenly along your skin, and miniscule bits of rust on your razor cause irritation and create a breeding ground for bacteria on your skin. Replacing your blade -- and keeping it clean -- will keep your skin smooth and healthy.
When to Replace Your Blade
When determining the lifespan of your razor, focus on number of shaves, not days or weeks. Ideally, you should replace your razor blade every five to 10 shaves. The more surface area you cover in a single shave, the shorter your blade's lifespan. If you shave every other day, for example, each blade should last between 10 and 20 days.
Maximize the Life of Your Blade
Rinse your blade carefully after each use, and dry your blade thoroughly with a clean towel to prevent rust formation and bacterial growth. Anecdotal evidence suggests that keeping your blade dry between shaves can significantly increase its lifespan, but go by the way your skin feels to decide when it's time to toss your blade. Signs that you're due for a replacement include skin irritation, stubble or needing to use multiple passes with your razor.