Because there are no expiration dates on things like mascara, eye shadow, or foundation, there's a bit of a debate about when it's best to toss them out and start fresh. While Dr. Torres says you shouldn't use any product longer than three months, Dr. Wu says that if the makeup appears to be safe, then it should be all right to use. However, she says, "If the color has changed, or there are different colored specks sitting on top (which could be bacteria or fungus), then toss it."
But for products that do have an expiration date, such as lotions and lip balms, well, it's there for a reason, so you should really try to stick to it, just as you would for the milk in your fridge. "Some of the components in the beauty products have a shelf lifetime, just like food products," Dr. Torres says. "There's a time that you can use it. Otherwise, you will increase the chances that any microorganisms have been able to colonize and grow in these products." Many of these types of products contain active ingredients that just aren't effective after a while, he says.
For a complete guide to the life expectancy of specific makeup products, check out Daily Glow's guide.
Photo Credit: Daily Glow