He explains that legally, cosmetics companies don’t have to put expiration dates on their products, but it is commonly suggested that you toss your mascara after three months. Yes, really. This mascara from Glossier is one of my all-time favorite mascaras. It gives lashes natural-looking length and definition (TBH it doesn't even look like mascara, just really good natural lashes) thanks to tiny tubing fibers and a lightweight, flexible formula. Plus it comes in two shades—an inky black and warm chocolate-y brown that I personally love. Luke Arundel, resident optometrist for Optometry Australia, warns of two common eye makeup mistakes that could lead to long-term eye damage. First, don’t apply makeup to your inner lash line, aka the waterline. So many of us have been doing it for years, but it’s really bad for your eyes. You could be spreading bacteria on the surface of your eyeliner. And since it’s hard to get the waterline truly makeup free, bits of eyeliner and mascara could be making their way into your eyelids, causing irritation.