Cheat Sheet: Exactly When You Need to Replace Your Makeup

Over time, foundations can change color or start to separate, two easy-to-catch expiration warning signs that Purdue says to keep an eye out for. She also notes that you're going to want to take special care with any foundations that don't come with a pump, as your fingers can contaminate the product, causing it to go bad faster.

Image via @fentybeauty