Important: Dermatologists Explain How to Apply Sunscreen Correctly

And how much you need to apply.

That’s why we've tapped three dermatologists to explain the steps in choosing and applying sunscreen correctly—and what could happen if you don’t. Read on to find out how to properly block out those pesky UV rays.

Meet the Expert

Dr. Hadley King is a board-certified dermatologist specializing in cosmetic and surgical dermatology. She is the owner of Dr. Hadley King dermatology in New York City.

Always go for SPF 30 or higher.

Contrary to some theories, the practice of applying sunscreen is important no matter your skin tone. “Melanin, or the pigment of the skin, is like Mother Nature’s sunscreen,” says Dr. Joshua Zeichner, director of cosmetic and clinical research in dermatology at Mount Sinai Hospital. “That said, darker skin is thought to only give protection at about a level of SPF 3.” Choose at least an SPF 15, though it's even safer to stick to 30 and above.

Of course, if you have fair skin—which tends to be more sensitive in general— the higher the SPF you use, the better. The fairest skin should aim for SPF 50 or higher, according to Dr. Will Kirby, board-certified dermatologist and Chief Medical Officer for LaserAway. Generally speaking, most skin tones should stick to a product that’s at least SPF 30 and has the words “broad-spectrum” on the bottle (which means it’s effective in blocking both UVA and UVB rays).

Find the right formula for your needs.

There’s not necessarily one type of formula that’s better than the other—it’s strictly up to your preferences. (For example, I love spray sunscreen because of how convenient it is to apply—but am I even applying it correctly? More on that later.)

Dr. Kirby recommends a sunblock over a sunscreen. If you’re not clear on the difference, it’s essentially this: A block will, as the name suggests, block UV rays, whereas a screen will absorb them. They both will be called “sunscreen” on the label (and will be used interchangeably throughout this article), but the trick is to check the back panel for the ingredients list. “The two types of blocks are titanium dioxide and/or zinc oxide,” he says. Technically speaking, sun-blocking formulas are called physical sunscreens, whereas formulas with ingredients that absorb are called chemical sunscreens. You can read more about the differences here.

“Ultimately, the best sunscreen is the one that you’re actually putting on,” says Dr. Zeichner. “But with so many textures and consistencies on the market nowadays, there’s something for everyone.”

Also, consider your skin type. If you have sensitive skin, it’s best to stick to a mineral-based sunscreen that may be less likely to cause irritation. If you’re acne-prone, try finding a non-comedogenic formula for the parts of your body that tend to break out. And if you have a darker complexion, thankfully the choices for non-chalky formulas are much wider than ever. We recommend Elta MD's UV Clear SPF and Drunk Elephant Umbra™ Sheer Physical Daily Defense Broad Spectrum.

Also of note: tinted sunscreens and sunblocks are specifically formulated to accommodate all skin tones—so you should be able to seek out a product that complements your complexion perfectly.

Take it slow—and use more than you think you need.

Spoiler alert: You’re probably not doing it right (I know I haven’t been).

“Most people only apply 25–50 percent of the recommended amount of sunscreen,” says Dr. King. “The guidelines are to apply one ounce—enough to fill a shot glass—to the exposed areas of the body, or if you’re using a spray, apply until an even sheen appears on the skin and rub it in.”

Also, keep in mind that it’s always a good idea to apply before you even walk outside. “Don’t rush, and apply in front of the mirror so you can see what you’re doing,” says Dr. Kirby. “Apply the first layer at home before you go out— when you’re already out, you tend to rush.”

If you’re with someone, ask them to do your hard-to-reach areas—there’s nothing worse than a sunburn on your back with the outline of an overstretched hand on it (been there).

And, generally speaking, don’t forget to use your common sense. Barrier protection is essential, says Dr. Kirby—so remember to bring things like sunglasses, a hat, or extra layers (like long sleeves) with you if you’ll know you’ll be exposed to the sun for a prolonged period of time. And keep in mind that peak sun exposure hours are 10 a.m. to 4 p.m.—so be extra-cautious if you’re out and about during that timeframe.

And reapply, reapply, reapply.

Fun fact: No sunscreen is “sweat-proof” or “waterproof” anymore, according to the Food and Drug Administration. “Instead, the label will say ‘water-resistant’ and for how many minutes, typically either 40 or 80,” says Dr. King. So make sure to reapply after any watery activity within that time frame.

Regardless of activities, though, you should always reapply at least every two hours, or the SPF level will get diluted, according to Dr. Zeichner.

Not in the sun? You still need to apply.

You might roll your eyes at this, but it’s so important to wear sunscreen on any exposed body part, regardless of the weather or climate, even if you’re only outside while you’re walking to the subway in the morning.

“Incidental exposure adds up quickly and UVA can penetrate cloud cover,” says Dr. Kirby. “So even if you don’t burn in the winter, you’ll still get premature aging from unintended sun exposure.”

In fact, studies in Australia tracked the skin of those who use sunscreen every day—despite the weather or daily activities—and those who used it only when it was particularly sunny outside. The results? Those who applied sunscreen every single day had skin that aged significantly slower—24% less in the daily sunscreen group than in the discretionary sunscreen group.

Incidental exposure will definitely add up over a lifetime—so don’t take any chances. Dr. Zeichner compares applying sunscreen to brushing your teeth: If you miss one day, there probably won’t be major consequences—but if you stop brushing altogether, you’ll get cavities. Similarly, missing a single day of sunscreen during your regular commute likely has little impact, but missing every day will equate to a lot of exposure over your lifetime.

What about the face?

Typically, you can apply the same sunscreen you use on your body to your face, unless you’re acne-prone (in which case, again, you should find a good non- comedogenic formula, like these formulas that we love).

But you need to be extra-careful with your visage. This means not spraying directly onto your face (if you have spray sunscreen, put it in your hands first, then rub it in) and also covering all of your bases.

“I’ll tell my patients to apply from the center of the face and then rub outwards into the hairline so there aren’t any missed areas,” says Dr. Zeichner. Commonly missed areas include the hairline, your hair part, the neck, and your ears—so make sure to give those areas some extra love. According to Dr. King, you should be applying about a quarter-sized dollop worth of sunscreen to your face alone.

Of course, makeup with sunscreen baked in is popular for a reason, and that works too. But it gets tricky when it comes to reapplying throughout the day if you’re wearing a full face of foundation—which is why Dr. King recommends a powder formula, like Mineral Powder Sunscreen from Brush on Block. Not only does it offer physical protection with zinc and titanium, it’s also the perfect texture to go over makeup. “Powder is easy to apply so you won’t complain about greasiness, and it’s totally smell-free and translucent. It’s portable, convenient, and the perfect way to reapply over makeup.”

American Academy of Dermatology Association. Sunscreen FAQs.

United States Environmental Protection Agency. Ultraviolet (UV) Radiation and Sun Exposure.

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