Dermatologists Reveal How Often to Apply Sunscreen

If you apply sunscreen in the morning and then promptly forget about it for the rest of the day, are you really getting the sun protection you need? It turns out, probably not. We asked dermatologists how often to apply sunscreen for the best protection, and sadly, once a day isn’t cutting it.

If you only apply sunscreen once a day (or even less), you’re not alone. But forgetting to reapply often throughout the day doesn’t just result in an uncomfortable, itchy sunburn—it can also lead to potentially deadly skin cancer. In fact, our risk of developing melanoma doubles when we have five or more sunburns, according to the Skin Cancer Foundation.

Meet the experts: Heather Woolery-Lloyd, M.D., a board-certified dermatologist and director of Ethnic Skin Care at the University of Miami Department of Dermatology; Leslie Baumann, M.D., a board-certified dermatologist, researcher, and founder of Baumann Cosmetic Dermatology

That means being diligent about your sunscreen application is key to protecting yourself in more ways than one, but how often do you actually have to apply it for the best results? Ahead, dermatologists reveal once and for all how often to apply sunscreen and share their tips for building the habit into your routine.

To stay protected all day, you need to reapply every two hours, according to Heather Woolery-Lloyd, M.D., a board-certified dermatologist and director of Ethnic Skin Care at the University of Miami Department of Dermatology. If you’re swimming or sweating a lot, you’ll need to reapply more often.

And don’t be afraid to be liberal with your application. Most people don’t apply enough sunblock in the first application, so they aren’t getting the same level of protection as stated on the label, explains Leslie Baumann, M.D., a board-certified dermatologist, researcher, and founder of Baumann Cosmetic Dermatology. “This makes the sunscreen less effective, causing it to lose its ability to protect the skin,” she notes.

Think you can skip sunscreen when it’s cold or cloudy outside? Not so fast. Ultraviolet light, including UVB rays that damage your skin, may be less present on a cloudy day, but UVA rays are just as strong and cause more skin damage, per Dr. Baumann. In other words, you still need to wear sunscreen on rainy days and even during cold weather activities like skiing.

As a general rule, reapplying sunscreen every two hours will protect you from the sun’s harmful rays. But there are a few situations where you may want to reapply more often:

• When you’re driving. “People underestimate how much sun exposure they get when they’re in the car,” Dr. Woolery-Lloyd says. Whether you’re the driver or a passenger, there’s a good chance you’re in direct sunlight, so you definitely want to abide by the two-hour reapplication rule. Dr. Woolery-Lloyd says she tells her patients to be extra cautious during long commutes.
• When you’re swimming. Water-resistant sunscreens are great, but they still need to be reapplied every two hours. You should also reapply sunscreen every time you dry off with a towel. When you wipe away the water, you’re also wiping off your sunscreen.
• When you’re sitting next to a window. You’re not safe from the sun’s rays just because you’re indoors; windows actually make it easy for the sun’s rays to get to you, whether they’re open or closed. “If your office has a window, you can bet that you’re actually getting quite a bit of sun,” Dr. Woolery-Lloyd notes. So if you’re sitting by a window for an extended period of time, follow the sunscreen rule and re-up every two hours (or more).

There are two types of sunscreen: those with physical or chemical blockers. Physical (or mineral) sunscreens contain ingredients like zinc oxide or titanium dioxide that sit on the skin, physically preventing UV rays from penetrating it. Chemical sunscreens have ingredients such as avobenzone and octisalate, which absorb UV rays before they can harm your skin. Physical sunscreens tend to be better for sunscreens for sensitive skin, but both types are safe and effective, according to the Skin Cancer Foundation.

To understand how sunscreen works (no matter which type you choose), think of it like a cup that gets filled by the sun’s rays, Dr. Woolery-Lloyd explains. After a few hours, the cup gets full and can’t absorb any more rays, so they go into your skin instead. “Reapplying sunscreen is like putting out a fresh cup to absorb the sun’s rays, rather than letting it get into your skin,” Dr. Woolery-Lloyd explains.

It’s easy to forget to reapply your sunscreen, but there are things you can do to help you remember. To get into a daily habit, try adding it to your regular routine. “Apply sunscreen in the morning after you brush your teeth, then apply it again before you go to lunch or anytime you are headed outside,” Dr. Baumann suggests. Don’t forget areas like your ears, neck (front and back), chest, and the top of your hands.

Above all, find a sunscreen you love, especially for your face (since reapplying here can be a bit tricky). If you actually like the formula, you’ll be more likely to stick with it. There are tinted sunscreens that offer light coverage, moisturizers with SPF if you like to go bare-faced, and powder sunscreens that make reapplying over makeup easier than ever.

Destinee Scott is an editorial fellow and a graduate student at New York University. She graduated magna cum laude from St. John’s University and has a passion for inspiring people to live their best lives. She is also a blogger and an avid-candle shopper. 

Jenn Gonick is Prevention’s Assistant Editor, and was previously an editorial intern. Prior to returning to Prevention, Jenn worked at Business Insider, writing about all things commerce and playing an active role in covering tentpole deal day events, including Prime Day, Black Friday, and Cyber Monday. Jenn is a graduate of George Washington University, where she studied English, Communication, and Applied Ethics. A lifelong wellness and mental health advocate, she’s committed to combatting misinformation and making health journalism more ethical and accessible.