There are two types of razor we usually have in our lives.

One that’s blunt as a butter knife, and the (rarer) type that’s so new we end up cutting ourselves by mistake.

But if we were fully functioning humans organised enough to replace our razors at a sensible time, when should we do it?

Rather than the amount of time that’s elapsed since you bought it, you should swap it after shaving a certain number of times.

Every five to seven, to be precise.

Dermatologist Whitney Bowe told Refinery29 that after just a few shaves, a razor will have begun to be exposed to bacteria:

And that’s especially if you leave it somewhere damp, like in the shower.

‘Leaving it in the wet, dewy shower will cause the blade to rust much faster, and will also leave it open to being exposed to bacteria much more,’ she said.

Ever get those little red bumps on your skin after shaving? Yep, it’s likely that’s thanks to having a bacteria-packed blade.

Because think about it – shaving, which is essentially cutting loads of tiny tiny nicks into your skin – is the perfect time for bacteria to access your body.

And besides those red bumps, keep an eye out for the obvious, such as rusting or dulling of the blade.

Any tugging or nicking of the skin should tell you it’s time to toss it,’ Whitney explained.

If the prospect of forking out for loads more razor blades fills you with dread, two things can preserve them: rinse them thoroughly after use, and keep them in a dry place.