Ashlee Williams, MD (Host): Sunscreens today prevent sunburns, skin cancer, and even signs of aging such as wrinkles, and age spots. But not all sunscreens are created equal. From choosing the right SPF, lotions versus sprays, chemicals versus minerals, how do you choose the best option for your skin?

Welcome to the Healthier You Podcast. I'm Dr. Ashlee Williams. And today, I'm joined by Dr. Tola Oyesanya, a board-certified dermatologist about how to decode the labels on sunscreen and pick the best option for your skin. Welcome, Dr. Oyesanya.

Tola Oyesanya, MD: Thank you so much for having me.

Host: I really appreciate this important topic. So, let's just start with what does SPF mean and what do all the numbers associated with SPF mean?

Tola Oyesanya, MD: Absolutely. So, SPF stands for sun protective factor. It's a measure of how well sunscreen protects our skin from the harmful rays of UV radiation from the sun, ultraviolet rays. And that's really what causes a sunburn. And so, ultraviolet rays, especially ultraviolet rays A, UVA rays. Can also cause sunburn. They cause . They cause cancer. And so, you want to make sure you're protecting yourself from those rays.

Think about SPF as sunburn protective factor, and the number that follows SPF really tells us how much of UV rays that the sunscreen can filter out. And so when we look at the numbers, SPF 15 tends to filter out about 93% of the UV rays. Not quite enough. SPF 30 filters out 97% of the UV rays, which is a better number to aim for. And then, SPF 50 and above filters out 98% of the rays, but it is totally impossible to filter out 100% of the sun's rays. So when you're searching for a sunscreen, you want to make sure that you're looking for a sunscreen that's checking all the boxes. And the boxes are being water-resistant, being at least SPF 30, because you want to block out at least 97% of the sun's rays. And also being broad spectrum, meaning that you're blocking out both UVA and UVB rays. And so if you are wearing a sunscreen with that, you're really making sure that your sunscreen is effective.

Host: Interesting. So, you mentioned that sunscreen should be water-resistant. How long does SPF last? When should we reapply it, especially if you're out in the water?

Tola Oyesanya, MD: So if you're out in the water, you really want to increase your frequency of applying sunscreen and that's because the water is just washing away that protection. And so at least every 90 minutes, but really 40-90 minutes is a better interval. And if you're not outside, if you're just kind of bumming around, maybe you're playing sports, every 90 minutes to two hours is a better interval.

Host: Wow. Every two hours.

Tola Oyesanya, MD: Yeah, it definitely is. It sounds frequent, but you want to make sure you protect yourself from the sun because otherwise you're more prone to getting a sunburn that can kind of ruin your day.

Host: Right. Okay. So, any tips to reapplying and applying the sunscreen?

Tola Oyesanya, MD: Absolutely. You want to make sure that you're applying sunscreen to all the areas that are not covered by clothing. And so if you're using a lotion, you can kind of see where you apply it. So, making sure you are covering every area with a thin layer of sunscreen. For hard to reach areas like your back, you want to make sure that you are asking for help, because otherwise you're going to miss a big patch of sunscreen on your back that could, you know, contribute to a sunburn later.

If you have thinning hair, you want to make sure that you're wearing a hat that has a wide brim or at least covering your scalp with sunscreen. A good, important point to make sure that you're thinking about is making sure to apply your sunscreen at least 10 to 15 minutes before going outdoors, because it does take some time for the sunscreen to really sink in and become effective. If you wait until you're outside already to apply the sunscreen, you're likely going to get a burn.

And another important point is that when you're outside, you want to think about wearing sunscreen all the time, especially during the summer, but even on a cloudy day in the winter, you can still get a sunburn. And so even when you're going outside just for a brief moment, maybe you're walking your dog, maybe you're on vacation, you're outside for a longer moment, you want to make sure to wear sunscreen.

Host: Interesting. I think most people don't consider wearing sunscreen on like a cloudy day because they think the sun's not out. Why should I put on sunscreen?

Tola Oyesanya, MD: And so, it's a very common misconception, but people who ski and they're out in the winter, it's cloudy, they can get sunburns. And that's because the exposure to sun is kind of bouncing off of, for example, the snow, which reflects that sun. And so, it makes it much more potent. And the same thing can happen in the winter against snowy banks. So, you're never fully protected just by clouds. You want to make sure you're protecting yourself from the sun no matter what.

Host: Okay. So, just a little bit more about the different types of sunscreen. So, we've seen that there's like a chemical and a mineral type of sunscreen. Can you speak on that and tell us a little bit about the difference?

Tola Oyesanya, MD: Absolutely. So, you're absolutely right that chemical and mineral or physical sunscreens are the most common subtypes you're going to see when you're out in the grocery store or in the drugstore looking for sunscreens. They both do protect yourself from the sun's harmful rays, but there are some distinct differences.

So when we think about chemical sunscreens, they are more like a sponge. They protect us from the sun by absorbing the UV rays. And that's why we have to reapply them often, because just like a sponge they do get saturated and no longer effective once they've been filled with water if it's a true sponge. And so, reapplying sunscreen kind of resets the clock and gives us another two hours of protection. Some of the most common active ingredients that you're going to see are oxybenzone or avobenzone.

On the other hand, when you think about mineral sunscreens, these tend to act more as a shield, as a physical protection from the sun. You might remember the old days where a lifeguard would have a thick layer of sunscreen on their nose. That was zinc oxide, and that's a very common ingredient in physical or mineral sunscreens. So, zinc oxide is one common ingredient and the other common ingredient is titanium dioxide. And just like that lifeguard that had a thick layer of sunscreen on their nose, most people tend to dislike mineral sunscreens because of that cast, that white cast that can be shown on the skin that might be very obvious.

But I want to tell you that mineral sunscreens have gone a very long way. They've come a very long way, which means that they're much more sheer, they tend to blend into the skin more just because of the technology that's been adopted recently. And so now, you're able to get lightweight tinted mineral sunscreens that tend to blend better with your skin tone. And so for that reason, they're my preference.

Mineral sunscreens are much better for sensitive skin, acne, rosacea. People with eczema or tend to have allergic reactions are better suited with a mineral sunscreen, because people with sensitive skin tend to have reactions to chemical sunscreens.

Host: Oh, interesting. It's good to know that mineral sunscreens have come such a long way. So for people with darker skin tones, can they just skip the SPF? Is it necessary for everyone regardless of skin tone? And if so, are there options for blending?

Tola Oyesanya, MD: So, I recommend that everybody, no matter their skin tone, wear sunscreen and that's because anyone can sustain a burn. You're right that people with darker skin are protected by melanin and they're much less likely to sustain a sunburn. But there still are pigment issues that occur with exposure to sun chronically. And so, protecting yourself from the sun with a sunscreen helps keep your skin tone even and clear. It also helps to protect you from skin cancer, though patients with darker skin certainly have a lower likelihood of skin cancer. However, it is not impossible and we certainly do have patients with darker skin who develop skin cancers.

So if you're a person of darker skin, I would make sure to wear a sunscreen that tends to blend better with your skin tone, specifically looking for ones that are more sheer when you apply them. And if you tend to prefer a mineral sunscreen, you want to look for some that are tinted. The tint tends to help it blend in with darker skin tones. You can even look for a tint that is labeled deep, and deeper tints tend to blend better with darker skin.

Host: That's a great tip. Do you have any tips on how to incorporate sunscreen into your daily skincare routine?

Tola Oyesanya, MD: Absolutely. I'm a big fan of two-in-one products, and so you want to look for a moisturizer that also has sunscreen in it. For example, you might see a BB cream that has a little bit of tint in it, and also has SPF 30, or you might just have a regular moisturizer with SPF 30 in it. Those are wonderful, because you no longer have to have two products. You can just apply one, kind of a grab and go.

When you're thinking about how to apply these, I would recommend simply cleansing your skin as you normally would and then following with that moisturizer with sunscreen kind of be captured into it. And always, it's totally fine to apply makeup over that if you prefer.

Host: That's great. Who doesn't love a good two-in-one product?

Tola Oyesanya, MD: Absolutely, absolutely. Thinking about how do you make sure that you don't forget to wear your sunscreen. I am also a big fan of keeping SPF lip balm with you if you are someone who tends to burn on the lips. It can be quite uncomfortable if you develop a sunburn on the lips. So, having a sunscreen-impregnated lip balm is also a great option.

And then, for people who tend to go out on walks during their workday or want to reapply their sunscreen, keeping something at your desk with sunscreen in it. Maybe a body lotion with sunscreen is also another great option. I do want to caution you against keeping your sunscreen in the car or in your trunk because sunscreen kept at very high temperatures will degrade, so it will no longer be effective. So, you definitely need to keep your sunscreen in a cool, dry place. The sunscreen you had from the pool last summer that's still in your trunk, toss it. It's not good anymore.

Host: That's a great tip. Well, thank you for all of this great information, Dr. Oyesanya. We learned a lot about what to look for when buying sunscreen. Here is a recap of what we learned. One, when searching for a sunscreen, look for a product that checks three boxes: water-resistant, at least SPF 30, and three, broad spectrum. If you buy sunscreen with those three things, it can effectively protect you from the sun. Two, apply one ounce of sunscreen, about a shot glass full, every two hours after toweling off and after swimming or excessively sweating. Three, mineral or physical sunscreen is preferred over chemical sunscreen. But the best sunscreen is the kind you'll wear and remember to reapply. Four, everyone, regardless of skin tone, should wear sunscreen every day. And five, incorporate SPF into your daily skincare routine. Those two-in-one products may be best for you. And for easy sun protection year-round, just wear the sunscreen.

For more skincare tips from our experts and other health advice, visit kp.org/doctor and listen to more episodes of Healthier You wherever you get your podcast. If you enjoyed this episode, be sure to share it with others who may find it helpful. Thank you. And from all of us at Kaiser Permanente, be well.