Does Your Sunscreen’s Expiration Date Actually Matter?

Rachel Krause
Tom Medvedich

Tom Medvedich

I was at my parents’ house in Connecticut recently, preparing for a trip to the man-made beach the same way I always do: by slathering my entire body in sunscreen until I look head-to-toe glazed like a human Krispy Kreme (original flavor). Regrettably, my tube of Jurlique Sun Specialist SPF 40 High Protection Cream was still idling on the kitchen table all the way back in Brooklyn, where I’d left it in my frenzy to get out the door.

My dad, a noted sunscreen connoisseur, offered me the pick of his personal stash, which would have been a godsend if not for one thing: They had all expired years ago. Some of them went as far back as 2011. When questioned, my dad insisted that expiration dates on SPF are “bullshit.” This is patently untrue, and also explains why he always gets sunburned. I spent the remainder of the afternoon sulking in the shade with a hat on.

“It’s just not worth taking a chance,” says dermatologist Debra Jaliman, founder of Sea Radiance. “Sunscreen contains preservatives which work to protect the product for a certain amount of time. After the expiration date, the active ingredients can decompose, and become inactive and ineffective.” Sure, it might be better than no sun protection at all, but you’re still putting yourself at risk of a sunburn. Them’s the facts.

MORE: How to Suss Out the Shelf Life of Your Beauty Products

And the dates themselves are far from arbitrary: “Sunscreens are regulated as over-the-counter drugs, and have been tested to ensure that the product is still safe and effective up until the labeled expiration date,” explains cosmetic chemist Jim Hammer of MIX Solutions. Once that date has passed, Hammer says, “The sunscreen agents can start to change chemically, becoming compounds which are not as effective for preventing UV damage.”

There’s a difference, however, between the shelf life of chemical sunscreens—with active ingredients like homosalate, octinoxate, and benzophenone, which absorb UV rays—and mineral-based formulas, which rely on physical protectants like zinc oxide and titanium oxide. While chemical actives lose their stability, the particles of physical sunscreens clump together and disperse. “[Mineral sunscreens] stay stable indefinitely, but the particles tend to agglomerate over time, which makes them less effective,” says cosmetic chemist Randy Schueller of The Beauty Brains. What you’ll get out of that is an uneven application, and an equally uneven sunburn to go along with it.

As Schueller says, “Sun protection depends on a thick, uniform covering on your skin.” A half-assed sunscreen application, whether you’re going too easy on the amount or getting it out of a bottle that should have been thrown away two years ago, just isn’t going to cut it. Sorry, dad—maybe you should reassess your hoarding situation and consider buying a new one every summer instead.

MORE: What’s the Difference Between Physical and Chemical Sunscreens, Anyway?