life·9 min read

Sunscreen 101: What to Know, What to Buy, and How to Use It

Sunscreen 101: What to Know, What to Buy, and How to Use It
Design: theSkimm | Photo: La Roche-Posay, Sun Bum, Simplicity
Apr 7, 2022
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Sunscreen is a crucial element of any skincare routine. It’s especially important in the summer — but really, you should be using it all year round, no matter your skin type or age. To protect against skin cancer and premature aging.

We know the sunscreen market is vast and sometimes confusing. And not all sunscreens are created equal. So we talked to Dr. Nazanin Saedi, a Philadelphia-based dermatologist, for a few SPF recs and to break down everything you need to know. Time for some (protected) fun in the sun.

First, a glossary

SPF: Sun protection factor. It measures the level of protection against UVA and UVB rays.

UVA rays: It’s the kind of sun that leads to premature aging and wrinkles, and can get through windows and glass. It can also lead to skin cancer. 

UVB rays: The ones that give you sunburn and can lead to skin cancer. 

Broad spectrum: Not actually a fake marketing term. This means the sunscreen protects against UVA and UVB rays. Which is a good thing.

Mineral vs chemical: Mineral (or physical) sunscreen acts like a physical blocker. Aka it repels or reflects the UV light. The American Academy of Dermatology (AAD) recs physical sunscreen for people with sensitive skin. Chemical sunscreens absorb (rather than repel) the UV light so your skin doesn’t. The AAD says chemical sunscreen is usually easier to rub into your skin without leaving behind a white residue. 

Zinc oxide: The SPF buzzword of the moment — and not in a bad way. It’s an active ingredient found in mineral sunscreens and is “great because it’s a physical blocker,” Saedi says. “It reflects the UV rays [and] has great protection.” 

Lotion vs spray: Many derms will advise lotions over sprays, Saedi says. Because with sprays, they’re harder to see and you don’t really know how much is coming out. Or if you’re using enough. Plus, some are worried about consumers inhaling the chemicals in aerosol products. (Psst: The AAD says to avoid using sprays around your mouth and face for this reason.) But because sprays often increase compliance — they’re so easily applied and reapplied — Saedi often recs ’em. So when it comes down to it, any sunscreen > no sunscreen.

Water resistant vs waterproof: Water resistant = you’re protected for up to 40 minutes in water. If a label says “very water resistant,” you’ve got 80 minutes, which, PSA, is less than the two-hour reapplication mark. Oh, and no sunscreens are waterproof,” so don’t get fooled.

Sunscreen application 101

  • Yes, you need to wear sunscreen every single day. Even when it’s cloudy or if you’re inside, because certain UV rays can penetrate through glass.

  • Apply about 1 ounce of SPF to your exposed skin every two hours you’re in the sun. That’s approximately the size of a shot glass.

  • Reapplication is vital. Once in the morning isn’t going to cut it. And if you’re swimming, reapply more frequently.

  • Don’t neglect your ears, feet, neck, and scalp. Any skin that’s exposed needs sunscreen. And it’s best to put on your first layer 15 minutes before you go outside.

  • The AAD recommends a broad spectrum, water resistant SPF of 30 or higher. SPF 30 blocks 97% of the sun’s rays. “After 30, the difference is nominal,” Saedi says. Anything above is just slightly more effective. Plus, there are no sunscreens that can block 100% of the sun's rays.

  • If your makeup has SPF in it, you should still wear sunscreen. Many experts point to the fact that makeup with SPF often doesn’t have broad spectrum protection. They also note that most people don’t apply enough makeup to actually protect against the sun effectively. (Remember that 1 ounce rule? And hitting every nook and cranny like your neck and eyelids?) 

  • Generally, sunscreen should be the last step in your daytime skincare routine. If your makeup includes SPF and you use sunscreen on top, you’ll be protected by the SPF of whatever your top layer is, Saedi says. (So if your makeup has SPF 15 and you put SPF 30 over it, you don’t get 45; you’ll get a protection factor of 30.) 

And finally, some recs…

The best kind of sunscreen is one you’ll actually wear. Here are some options for ya...

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Skimm'd by Lindsay Schneider, Margo Ghertner, Emmy Favilla

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