As much as we'd like to be with our beloved makeup, lotions, and serums forever, using beauty products that are way past their prime won't do you any good. Besides the sub-par performance, they can be a breeding ground for bacteria and cause irritation—yikes! To know the toss-time for each beauty product, refer to our shelf-life guide below. Are many of your goodies expired? Don't worry—that just means it's time for a new haul!