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What doctors wish patients knew about wearing sunscreen

Mar 18, 2022

Wearing sunscreen is one of the easiest ways to protect your skin’s appearance and health at any age. But more often than not, people are not wearing—or reapplying—sunscreen properly. Knowing what type to buy and how to properly apply sunscreen are key to preventing skin cancer, which is often caused by too much exposure to ultraviolet rays from the sun or artificial sources such as tanning beds.

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The AMA’s What Doctors Wish Patients Knew™ series provides physicians with a platform to share what they want patients to understand about today’s health care headlines, especially throughout the COVID-19 pandemic.

In this installment, two AMA members took time to discuss what patients should know about wearing sunscreen. They are:

  • Evelyn Jones, MD, a dermatologist and owner of WellSprings Dermatology and WellSprings SkinCare in Paducah, Kentucky.
  • Klint Peebles, MD, a dermatologist in Washington and suburban Maryland at Mid-Atlantic Permanente Medical Group, a member of the AMA Health System Program.

Ultraviolet light (UVL) “is our biggest risk factor for skin cancer,” said Dr. Jones. “The UVL rays cause damage to our skin cells increasing the risk of skin aging and skin cancer. Using sunscreen on a daily basis is critical to protect the skin cells from this damage. This includes cloudy days when up to 80% of the UVL rays will penetrate through the clouds.”

That is why “you want to look for  a sunscreen that is labeled as ‘broad spectrum,’” said Dr. Peebles. “This means that it covers both ultraviolet A and ultraviolet B radiation, which are specific types of rays from the sun.”

But “keep in mind that no sunscreen can block 100% of the sun’s rays,” Dr. Peebles said.

Discover what doctors wish patients knew about skin cancer risk and prevention.

“There is a significant difference between a chemical sunscreen and a physical sunscreen, or physical blocker,” said Dr. Jones. “Physical sunscreens contain the active ingredient zinc oxide or titanium dioxide.”

“Physical blockers really work like a shield because they sit on the surface of the skin and deflect the sun’s rays,” said Dr. Peebles. “These are generally better for people with sensitive skin and are also the ones that, unfortunately, as of now are more likely to leave that annoying white film on the skin.”

But the good news is that, when using physical sunscreens, “you’re protected as soon as you apply the sunscreen to the skin, allowing you to avoid having to wait 30 minutes before going outdoors,” said Dr. Jones. “The physical sunscreens are also a little more resistant to water, so if you’re going to be swimming, this type of sunscreen is a much better option.”

The other option is a chemical sunscreen—or chemical blocker—which contains chemicals like oxybenzone, octinoxate, octisalate and avobenzone, among others.

“With chemical blockers, they’re going to work like a sponge and absorb the sun’s rays and get rid of them by converting them to heat,” said Dr. Peebles, noting that “they’re often easier to rub into the skin and are the ones that have generally been more commercially available.”

However, “chemical sunscreens can be sensitizing to people, especially with rosacea,” said Dr. Jones. “If you start having a rash related to sunscreens, it will most likely be caused by a chemical sunscreen.”

Additionally, some chemical sunscreens “have been a little bit controversial because of stories linking them to absorption into the body or possibly environmental concerns,” said Dr. Peebles. “We are closely following this research, but to date no significant data has emerged that would compel a change in our general sunscreen recommendations.”

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What doctors wish patients knew about skin cancer risk and prevention

The Food and Drug Administration (FDA) has not defined the term waterproof “when it comes to how this term pertains to sunscreens,” said Dr. Peebles. “The terms they do define would be ‘water-resistant’ and ‘very water-resistant.’

“‘Water-resistant’ means that it stays effective for about 40 minutes in the water, whereas ‘very water-resistant’ stays effective for about 80 minutes in the water,” Dr. Peebles added, noting that “we still, regardless, encourage you to reapply sunscreen every couple of hours and after exposure to water and sweat.”

“The term ‘baby-proof’ on sunscreen is also not FDA-defined, but usually what that means is that it's a sunscreen that is designed for more of a sensitive skin type,” said Dr. Peebles. “It usually means it contains only physical blockers because we tend to avoid chemical blockers in very young children.”

That is because “the physical blockers are less likely to irritate the baby’s skin than the chemical blockers,” Dr. Peebles said. “It is also important to note that sunscreen is usually recommended starting at six months and older.

“Younger than six months, we should primarily focus on other sun-protection strategies like seeking shade and protective clothing,” Dr. Peebles added.

“A lot of people will also ask about what the word ‘sport’ means on the sunscreen labeling,” said Dr. Peebles. “That’s also not defined by the FDA.”

“Generally, when the industry puts that term on sunscreen, they’re referring to it being water-resistant or very water resistant,” Dr. Peebles said, adding that it also means sweat-resistant.

“When we think about ultraviolet radiation—which is what we're concerned about in terms of these harmful sun rays—we split that generally into UVA and UVB,” said Dr. Peebles. “Ultraviolet A is really what I like to call ‘the aging ray.’

“These are the rays that prematurely age the skin. They're going to cause wrinkling, fine lines and age spots,” Dr. Peebles added. “They also pass through window glass, so whether it's glass in the office, your home or car they get through.”

“On the other hand, ultraviolet B, or UVB, would be what I call the burning ray, and these would be the primary cause of sunburn,” said Dr. Peebles. “Those are largely blocked by window glass, but not always—it just depends on the context.”

Learn more from this JAMA Dermatology Patient Page on sun safety.

When choosing a sunscreen, “you're going to look for an SPF—or sun protection factor—on sunscreen of 30 or higher,” said Dr. Peebles. “SPF basically tells you how much UVB light that the sunscreen can filter out.

“For instance, an SPF of 15 is going to filter out 93% of the sun’s UVB rays,” Dr. Peebles added. “An SPF of 30 is going to filter out about 97% of the sun’s UVB rays.”

Find out what doctors wish patients knew about summer skin safety.

“The challenge of using spray or foam sunscreens is that people either don't use enough or they do not adequately rub in the sunscreen, which gives them a false sense that their skin is fully protected,” said Dr. Jones. Which is why “application technique is going to be important.”

When it comes to spray sunscreen, “what I tell people is it’s really just a different vehicle, especially for men in hair bearing areas,” she said. “I get it. The spray and the foams are definitely better tolerated, but you want to adequately spray multiple times to get enough on and then rub that in with your hand.”

That’s “because spray sunscreen doesn’t get absorbed well with just a spritz and sitting on top of the skin,” said Dr. Jones. “So, it’s not only spraying enough of it—but then rubbing it in too.”

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When it is cloudy, “80% of ultraviolet light passes through clouds. So if it is cloudy, we need to still apply sunscreen,” said Dr. Jones. “That is why—365 days of the year—if you just plan and are intentional about putting sunscreen on everywhere the sun can see, then you’re going to be better off and better protected.”

“Even when it's cloudy, you can still tell that it’s daytime,” said Dr. Peebles. “And if you can tell that there's light around, then you are getting rays from the sun that are reaching your skin.

“Now the risk may not be a as high as on a bright summer day on a beach when there's not a cloud in the sky, but that skin cancer risk, that aging risk, all of that is still very much there even on a cloudy or snowy day,” Dr. Peebles explained.

“We often get asked about expiration dates when it comes to sunscreen. Sunscreens do expire,” said Dr. Peebles, noting “the FDA requires that all sunscreens retain their strength for at least three years.”

“It's important to know that if you're using sunscreen right, a bottle shouldn't actually last very long,” Dr. Peebles said. “Chances are, if you're asking the question about expiration dates on sunscreens, then you probably aren't using them  correctly.”

“I am also often asked about all of those sunscreens that are combined with insect repellants, especially in the summer,” said Dr. Peebles. “We do generally avoid those, mostly because they don’t ideally go together.”

This is “largely because when you think about it, sunscreen should be applied liberally and often, whereas insect repellent should be applied more sparingly and less often,” Dr. Peebles explained. “If you’re using each of them correctly, they really don’t need to be in the same product or formulation.”

“I personally recommend keeping your sunscreen separate from your insect repellents,” said Dr. Peebles, adding that using “products that contain both may detract from one or the other in terms of what you’re using them for.”

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