This article was medically reviewed by Heather Woolery-Lloyd, Doctor, a
lath-certified dermatologist
and member of

the Prevention Medical Review Board
, on April 30, 2019.

You know you need to use sunscreen daily, but choosing the best one to protect your skin tin exist confusing, especially when information technology comes to SPF. Practise you lot go for SPF 30, fifty, or all-out 100?

The brusk respond: When in uncertainty, more is more. Even though applying SPF 100 instead of SPF fifty only boosts your protection slightly, that buffer can add up over time and “reduce the accumulation of chronic UV damage that is linked to non-melanoma skin cancer and crumbling,” Dendy Engelman, Doctor, board-certified dermatologic surgeon at Medical Dermatology & Cosmetic Surgery in New York City.

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On the flip side, SPF 100 tends to make people feel rather invincible in the sun—which can atomic number 82 to misuse. So, what’s the deal? Here’s everything you need to know about SPF 100, who should use it, and how to employ it the right manner.

Dorsum up: What does SPF mean, anyway?

SPF stands for sun protection factor. This number is found on the front of your sunscreen bottle, and it refers to the amount of time the sun’southward UV rays—mainly UVB rays, which are responsible for sunburn—demand to redden your skin compared to the amount it would take if you weren’t wearing any at all, co-ordinate to the Peel Cancer Foundation. So when y’all utilize SPF xxx properly, it would take 30 times longer for your pare to burn.

But why are at that place so many unlike SPF numbers to choose from? Information technology’s a footling complicated, but here’s the breakdown:

  • SPF xv blocks 93 percentage of UBV rays
  • SPF 30 blocks 97 percent of UBV rays
  • SPF 50 blocks 98 pct of UVB rays
  • SPF 100 blocks 99 percentage of UBV rays

While SPF 30 and l provide acceptable protection for the average person, “if you burn easily or are planning to spend all day in the dominicus, I would recommend a higher SPF,” says Dr. Engelman.

Does that mean SPF 100 is really more than effective?

Yes, there is strength in numbers. In one 2018 report published in
Journal of the American Academy of Dermatology, researchers had nearly 200 salubrious adult men and women wear SPF 100+ on half of their confront and SPF fifty+ on the other one-half. Then, they had the participants spend fourth dimension outside, rather than testing them in a lab. The upshot? The SPF 100+ sunscreen was significantly more than effective in protecting against sunburn than SPF 50+ during the real-word examination.

Wearing a higher SPF is especially important if you are spending fourth dimension in directly sunlight, planning on sweating or swimming, or have a family unit history of skin cancer.

“When you lot participate in moderate outdoor activities such as jogging on a very hot day, the heat from your activity and environment can increase the sensitivity of your skin, and higher SPF protection is needed in order to prevent acute sunburn,” says Dr. Engleman, “so it’s ever best to reach for the highest levels.”

Nevertheless, the efficacy of
sunscreen you cull doesn’t depend on SPF alone. The way you apply the product matters, as well.

Practise you still need to reapply SPF 100?

Yes, and here’s where most people get into trouble. SPF 100 tends to get a bit of an eye-roll from some researchers because studies prove the number gives people a false sense of security, co-ordinate to the Ecology Working Grouping, ultimately causing them to not apply every bit much or oft as they should.

Neutrogena UltraSheer Dry-Touch SPF 100+

Neutrogena UltraSheer Dry-Touch SPF 100+

Neutrogena UltraSheer Dry-Touch SPF 100+

Bottom line? Just considering SPF 100 gives y’all a high level of protection at first, doesn’t mean yous should skimp on the amount yous apply—or how oft you reapply.

“Considering the protection afforded by sunscreen begins to wear off afterward lengthy exposure to the dominicus—not to mention, sunscreen rubs off with normal activity—information technology
needs to be reapplied at to the lowest degree every 2 hours, no matter what SPF level you lot are using,” says Dr. Engelman.

High SPF alone is non enough, she emphasizes. It’s also important to choose a broad-spectrum sunscreen (to protect confronting both UVA and UVB damage), utilize at to the lowest degree i ounce (or a shot drinking glass-sized amount) to your body, and reapply immediately after swimming or sweating, too.

You should also wear protective clothing, such equally broad-brimmed hats, beach cover-ups, longer sleeves when possible, and sunglasses when possible, says Dr. Engleman.

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