There's an Easy Way to Tell If Your Beauty Products Are Expired (Who Knew!?)

By Petra Guglielmetti, Glamour We often hear guidelines from dermatologists about how long we should use certain beauty products; the FDA has advice on this too. The one that always stands out in our minds is the three-month rule for mascara (whether we all adhere to such advice is another story entirely). It makes sense, and of course we want to avoid using expired products that could be crawling with grody, possibly harmful bacteria. Yet somehow, we've gotten this far in life without ever know...