How to Find the Right Sunscreen, According to a Dermatologist

You know that SPF is important, but what about all those other three-letter acronyms? UVA, UVB, UPF are all used when talking about protecting your skin from the sun, but what do they all really mean, and how do you protect yourself properly with sunscreen?

We’re tackling why applying sunscreen daily is every bit as important as brushing your teeth. In fact, according to Beth Goldstein, MD, adjunct professor in the Department of Dermatology at the University of North Carolina at Chapel Hill and founder of Modern Ritual, year-round sun protection can reduce your skin cancer risk by 40 percent. We also spoke with board-certified dermatologist Lian Mack, MD, who mentioned that we should also be protecting our skin from the blue light put out by our computer and phone screens, which can cause skin discoloration.

What is the difference between UVA and UVB?

Ultraviolet A, or UVA, is radiation from the sun that has particularly long wavelengths and is associated with aging skin. Ultraviolet B, or UVB, are the rays from the sun we associate with getting a sunburn, and they usually have a shorter wavelength.

What does UPF mean?

UPF stands for universal protection factor, and this signifies how much radiation (both UVA and UVB) a fabric allows to get through — so consider this when buying clothing that promises sun protection.

Why it’s important to wear sunscreen year-round

“Most people know they’re at risk of sunburn and skin damage in bright sunshine and warm weather, but they don’t always realize that harmful UVA rays are present all year long,” Dr. Goldstein says. “Although UVA rays don’t cause sunburns nearly at the rate of UVB rays, they’re potentially even more dangerous, because they penetrate more deeply into the skin, which may result in skin cancer, damaged collagen, wrinkles, and the irregular pigmentation we see as brown spots. Over time, UVA rays cause cumulative damage to the skin.”

This type of UVA ray comes through most window glass, so even when you’re inside — or in your car — your skin can be damaged. And don’t even think about a tanning bed, which uses UVA rays in incredibly high dosages.

According to Dr. Mack, it’s important to wear sunscreen even on days when you stay inside. “When indoors, the glass from windows blocks UVB rays, while UVA rays can penetrate it. Exposure to UVA accelerates the aging process and can also contribute to the formation of skin cancer by damaging DNA in skin cells.” She also says that because so many of us are working remotely, staring at our computer screens for hours a day, we should consider protecting our skin from blue light, too. “Most of our devices are emitting blue light or HEV light that may penetrate the skin resulting in discoloration.”

If you have a darker skin tone, that doesn’t mean you shouldn’t wear sunscreen. While darker skin contain more melanin, which absorbs UV rays, it is still susceptible to burns and other damage. It may not happen as quickly as it does to those with lighter skin, but it still occurs. Sun burns and advanced aging are still possible, so it’s always best to wear sunscreen to prevent those and possible skin cancer.

Why skin cancer the most common cancer in the U.S.

When it comes to preventing cavities, you wouldn’t only brush your teeth during a certain time of year and expect them to remain in perfect condition. Like oral care, skin cancer prevention is not a seasonal thing. It requires daily year-round care. At least one in five Americans will develop skin cancer in their lifetime.

The majority of skin cancer — 90 percent of the 5 million cases diagnosed in the U.S. each year — are caused by artificial or natural sun exposure over a lifetime. We get significant sun exposure before age 18 and, as adults, each time a sunburn or tan fades away, the damage to the DNA of the skin continues to accumulate.

What to look for in sunscreen ingredients

You’ll hear this time and again, but the best sunscreen is the one you’ll actually use. There are two main sunscreen formulations, mineral and chemical. The active ingredients provide protection but their protection mechanisms are different: Chemical sunscreen is absorbed into the skin while mineral sunscreens (also known as physical sunscreens) remain on the surface to block harmful rays.  

Dr. Mack says to be sure that no matter what kind of sunscreen you choose, mineral or chemical, that they have “broad spectrum” listed on the packaging. This way, you know you’ll be getting protection against both UVA and UVB rays. Also, be sure to grab something that’s SPF 30 or higher for the best protection, and something water-resistant if you know you’ll be in the water or sweating throughout the day.

Dr. Goldstein recommends mineral-based blocks to her patients alongside a comprehensive skin protection program which includes annual skin checks by a dermatologist. 

What SPF should you use?

Choosing the highest SPF sunscreen on the shelf won’t hurt you, but it won’t necessarily help you either. Mack recommends going no lower than SPF 30, which blocks 96.7 percent of UV radiation from reaching your skin. Opting for SPF 50 will block approximately 98 percent of rays. However, after an SPF of 50 there is little additional benefit.

How much sunscreen to apply daily

It’s tempting to slather on as much SPF as possible for maximum protection, but Dr. Mack says you really only need to follow a couple of rules. “For your face, I recommend using the two-finger method. Apply a streak of sunscreen from the base to the tip of two fingers and apply generously to your face,” she says. If you have any leftover sunscreen, use it on your neck and ears.

For the rest of your body, at least two ounces of sunscreen is recommended. Think of it as about the size of a shot glass in terms of volume. Don’t forget to get all those hard-to-reach places like your lower back and shoulders, and try not to skip the tops of your feet or the backs of your hands.

Makeup with SPF

Chances are you’ve noticed that your foundation, setting powder, or moisturizer has SPF baked right in, but that’s not the same as applying straight-up sunscreen. “Moisturizers are designed to penetrate the skin and to enhance the functionality of the skin barrier, whereas the purpose of SPF is to create a barrier between skin and the damaging rays of the sun,” Dr. Mack says. “If you are not going to use a separate sunscreen, a moisturizer with SPF is better than no SPF at all, but I prefer sunscreen sans the moisturizer.”

If you do choose to wear a moisturizer with SPF, be sure to take extra precautions to protect your skin from the sun with a sun hat or clothing with UPF, which will protect you from UVA and UVB rays.

The Best Sunscreen, According to Dermatologists