Silva: When you see any separation within the product. Whether it’s oil- or water- based, you’ll be able to see separation between the actual pigment of the makeup and the liquid. Unless it indicates that separation is part of the characteristics of that product, replace it. 

SM: Many of us will just wait until it runs out.

Silva: Well, you can use all of your makeup up until the very end of it, but it depends on how often you use that makeup and how you maintain its integrity. Some women keep their makeup in the refrigerator and that’s going to prolong the life of it. Also, if you’re only a weekend makeup kind of person, your product isn’t going to be contaminated as quickly.

SM: What’s the lifespan of mascara?

Silva: You should replace your mascara every other month or when it starts to get dry. Every time you take the wand out of your mascara tube, you’re introducing air into the product, which dries it out. There’s also all of this information that mascara can give you eye infections, but this only happens when you share it with someone else. So if somebody else uses it, get rid of it.