What Most People Get Wrong About Sunscreen, According to Doctors

By Terez Malka, MD
Medically reviewed checkmarkMedically reviewed
June 20, 2022

“Dad, what is that?” 

Walking behind his father on a Florida beach, Dr. David Morley noticed something on his dad’s calf that didn’t look right. It turned out to be melanoma, a dangerous skin cancer that about 200,000 Americans will be diagnosed with this year. While 8,000 die annually from the disease, Dr. Morley’s dad caught it early and was able to get treatment. 

What most people don’t know is that melanoma isn’t necessarily caused by the sun’s rays. Representing only 1% of skin cancers, but a majority of skin-cancer-related deaths, melanoma is thought to be caused by a variety of factors, including genetics. People with lighter-toned skin are about 20-times more likely to develop melanoma than people with darker-toned skin. A brand new study published in the medical journal Cancer Causes & Control shows that people who eat a lot of fish have a 22% higher risk of melanoma (to be clear, this does not necessarily mean that eating fish actually causes melanoma, as the study didn’t look at other important factors, like the number of participants’ prior sunburns).

But melanoma is just one danger. One in five people will develop skin cancer in their lifetimes, and wrinkles and other signs of aging are directly correlated with sun exposure. 

“People ignore the fact that it’s about more than melanoma,” said Dr. Morley, senior medical director at K Health and an emergency physician. “There are lots of other reasons to protect yourself from the sun.” 

Not everyone’s child is a doctor – and not everyone can follow all of the many, onerous recommendations on sun protection – so here’s what doctors want you to know when it comes to sun protection. 

How Do Doctors Balance the Risk of Sun Exposure With Living Life?

If you ask a dermatologist about sun protection, they’re likely to tell you to: 

  • Wear sunscreen every day, even if you aren’t going outside, even in the winter
  • Use at least SPF 30
  • During the summer, don’t go outside between the hours of 10 a.m. and 4 p.m., when the sun’s rays are most intense
  • If using chemical sunscreen, wait 30 minutes after applying to be in the sun
  • Reapply sunscreen every 80 minutes

If those are things you are able and willing to do, good for you. But for the rest of us, it’s about balancing the perfect with the “good enough,” said Dr. Chesney Fowler, medical director at K Health and an emergency-room physician. 

“As a doctor and a mom, my approach is very practical,” said Dr. Fowler. 

For her family, she uses whatever sunscreen is available, despite many chemical sunscreens containing substances that are more strictly regulated in other countries. Chemicals like oxybenzone, homosalate and octocrylene absorb into the bloodstream when applied to the skin and are being studied for health problems they may cause. They have not been shown to cause cancer, unlike too much sun exposure. “I’m fine with it if it can help us avoid what we know to be very dangerous, which is the cumulative effect of a small amount of radiation from the sun’s rays.”

Dr. Fowler’s family likes to go hiking, and they use bug repellent products that contain DEET, a chemical that some erroneously think is dangerous even though it is perfectly safe and does not cause cancer, according to the Environmental Protection Agency. But, she advises against using a combined sun-blocking and DEET product, because with sunscreen, you need to reapply every few hours, whereas with DEET, it lasts much longer and does not need to be reapplied. 

“I buy my sunscreen in bulk from the Dollar Tree and Costco,” said Dr. Fowler. “It comes in gallons, and we go through a lot of it in our house.”

@khealthofficial As Dr. Chesney Fowler would say, “better to do something imperfectly than to do nothing perfectly.” In this case, if you’re dreading putting on sunscreen today, something is ALWAYS better than nothing. #sunscreen #sunsafety #khealth ♬ FEEL THE GROOVE – Queens Road, Fabian Graetz

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How Much Sunscreen Should You Apply? 

For his family, Dr. Francis Goldshmid is more conservative. They follow the strictest guidelines from the American Medical Association, making sure to use the proper amount of sunscreen with each application. 

“Most people are not using enough sunscreen. Make sure you apply nine teaspoons to your body,” said Dr. Goldshmid, who is a family medicine doctor. 

It’s an oddly specific number, but here’s how it breaks down: 

Body partAmount
Face and neck1 teaspoon total
Legs and feet2 teaspoons each
Arms and hands1 teaspoon each
Front and back torso1 teaspoon each

That translates to about three large dollops of sunscreen, and it’s important to use it everywhere. Most skin cancers occur on the ears and top of the feet. If the hair on your head is thin, use sunscreen on your scalp, too. 

Additionally, Dr. Goldshmid does not recommend exposing infants under six months to any sun whatsoever. But when you do, cover as much of the body as possible with clothing, and consider a mineral sunscreen that contains zinc or titanium dioxide as its active ingredient, which may be less irritating than chemical sunscreens for sensitive infant skin. For all ages, an SPF over 30 is recommended by the American Academy of Pediatrics, and a proper amount should be used to ensure adequate protection.

“They have really sensitive skin,” said Dr. Goldshmid, whose recommendations come from the American Academy of Pediatrics.

@khealthofficial Gary and I want to remind you that you (and your skin) are not invincible 😞. Wear your sunscreen and reapply it properly! 🧡 Like if you love Gary🍊 #khealth #sunsafety #sunscreen #sunsafetytips ♬ original sound – khealth

How Much SPF Is Enough?

If you’re worried that SPF 30 is insufficient protection, even Dr. Goldshmid and his family use it. “SPF” stands for “sun protection factor” and what many people don’t know is just how effective SPF 30 is, compared with higher SPF-rated products. 

Even SPF-15 products block most of the sun’s harmful rays (93%). SPF 30 lets in half that amount, which translates to blocking 97% of the sun’s rays. SPF 60 lets in about half of 30. SPF 100 will block about 99%. 

Sun protection factor (SPF)
SPF 15Blocks 93% of harmful rays
SPF 30Blocks 96.5% of harmful rays
SPF 60Blocks 98.3% of harmful rays
SPF 100Blocks 99.1% of harmful rays

SPF isn’t just for creams. Clothing can have SPF ratings, too, but even clothing that isn’t officially SPF-rated can offer protection. 

“Wearing a shirt that has UV protection is great,” said Dr. Fowler, “but you don’t need a fancy SPF-rated shirt. Just wear a long-sleeved shirt to get protection.”

Following his father’s cancer diagnosis, Dr. Morley now wears a shirt when he swims. 

“Taking your shirt off to go swimming exposes a large part of your body, so I stopped doing that,” he said. “It’s the biggest thing I do that most people probably don’t.”

@khealthofficial There are many types of sunscreens out there, and all look different when applied. We swatched to show you! Link in bio to learn more about sun safety. #sunscreen #sunsafety #swatching #khealth ♬ 1 hop this time scruz – skwuz

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If You See Something Unfamiliar on Your Skin, Get It Checked Out

Despite its great powers, doctors want you to remember that SPF does not protect you from everything. Dehydration and heat stroke are also dangers when spending a lot of time in the hot sun. In areas near the equator, during peak hours, even strong SPF may not prevent you from getting a sunburn, and even one sunburn increases your risk of skin cancer, according to Dr. Goldshmid.

“Sunscreen does not make you invincible,” said Dr. Morley. 

Most importantly, if you spot something on your skin that seems like it has just appeared or looks strange, you should have it examined by a clinician. 

“If you see something, get it checked out, especially if it’s new and weird,” said Dr. Morley.

K Health articles are all written and reviewed by MDs, PhDs, NPs, or PharmDs and are for informational purposes only. This information does not constitute and should not be relied on for professional medical advice. Always talk to your doctor about the risks and benefits of any treatment.

K Health has strict sourcing guidelines and relies on peer-reviewed studies, academic research institutions, and medical associations. We avoid using tertiary references.

Terez Malka, MD

Dr. Terez Malka is a board-certified pediatrician and emergency medicine physician.