Sunscreen Expiration: What You Need to Know

All sunscreens have an expiration date printed on the bottle, and most are good for three years from the time of purchase. In a pinch, you can use sunscreen for an extra six months—but after that, it’s time to buy a new bottle. Sunscreens break down over time, and can interact with the material the bottle is made of, which can further alter their chemistry. Also, eventually the plastic bottle itself can degrade, meaning that it’s possible when you use old sunscreen you might actually be spreading plastic particles onto your skin. (Yeah, ew.)

MORE: Think You’ve Washed Off Your Sunscreen? Think Again, Because You’re Doing It Wrong.