Is the expiration date on sunscreen like carton of milk—non-negotiable? Or is it purely a friendly suggestion?
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We've all been there. You're running out the door to meet friends for a beach day when you remember, "Damn, the sunscreen!" You dig through the landmine of products in your bathroom cabinet before grabbing a faded SPF bottle. You try to remember the last time you used it (Was it a few months ago? Or two years ago?) and scan the bottle for an expiration date. But really: Does sunscreen expire?

Believe it or not, sunscreen does, in fact, have an expiration date. Because it's a generally unstable product, SPF formulas become less effective if left open (so always make sure the cap is completely closed!) or in extreme temperatures, says Rachel Nazarian, MD, a New York-based dermatologist and fellow of the American Academy of Dermatology (FAAD).

Expired sunscreen gives users a false sense of security and is less capable of protecting your skin, even if you consistently reapply, she explains. "Radiation from sunlight will not be effectively blocked or curbed with expired sunscreen, making the chance of burning and damaging your skin more likely." Yikes. Plus, along with a bad burn, using expired sunscreen could also cause skin irritation, says New York City-based dermatologist Debra Jaliman, MD.

Still, it really hurts to have to trash a mostly-full bottle of sunscreen, whether it's a drugstore brand or pricier tube. Is the cutoff date printed on every sunscreen bottle sold in the U.S. completely non-negotiable like that of a carton of milk—or can we take that date purely as a suggestion? (Crossing all the fingers.)

If the bottle has been opened and exposed to air, throw it out when you hit the expiration date printed on the packaging, says Dr. Nazarian. However, if it's unopened and has been stored in a cool, dry location, it can be used up to three months beyond the date on the bottle.

OK, but what if you found a bottle of sunscreen at the bottom of last summer's weekender bag and the expiration date has been rubbed off? Sunscreen usually has a three-year shelf life, Dr. Jaliman tells us, so if you bought it within that timeframe, you're probably safe.

Not completely certain? Squeeze a small amount of the lotion into your hand. If you see that the ingredients are separating, or if there's a change in color, texture or smell, throw it away, Dr. Jaliman tells us. That goes for sunscreen that's not yet expired, too—if it's looking a little iffy, she also recommends giving it the toss.

Our advice? Before you settle on last summer's sunscreen, check the expiration date. Can't find one? Make a pit stop at your nearest drugstore or stock up online (some of our favorite brands are Neutrogena, EltaMD, Drunk Elephant, and Coola) so that you have a fresh bottle for all your warm weather activities.

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