Summer is nearly here and temperatures have been heating up. That means it’s time to head to the beach. So is it OK to slather on that sunscreen that has been sitting in your trunk for a year? Probably not.
Sunscreens have a self life of about 3 years. However, most sunscreens are unstable at high temperatures (ironic, huh?). High temperatures can cause the ultraviolet absorbing chemicals like avobenzone and oxybenzone to degrade right in the bottle. When you apply a degraded sunscreen to your skin, you are not getting the SPF indicated on the bottle and in fact might be applying nothing more than a thick white moisturizer. Ideally sunscreens should be kept at temperatures no hotter than 77 °F (25°C) — the inside of your car in the beach parking lot can reach over 120° (50°C).
When you are at the beach, toss your sunscreen in the cooler; it will keep it from breaking down and will feel great on your skin when you reapply.
If you have an sunscreen that is more than 3 years old or a sunscreen that has been sitting in your car for any length of time, then buy a fresh one this summer. Otherwise, you might need this.
Post written by Jeffrey Benabio, MD. You might also like:
Photo credit: Tiago Macambira