How Often to Apply Sunscreen According to a Dermatologist -

Sunshine may boost your mood and help your body make vitamin D, but too much can harm your skin. To protect yourself, Penn State Health dermatologist Dr. Charlene Lam recommends applying sunscreen 30 minutes before going outside, and reapplying at least every two hours.Keep reading to learn why it’s so important to wear sunscreen every day this summer and explore more of Dr. Lam’s tips for staying safe while soaking up the sun.

Why wear sunscreen every day?

Wearing sunscreen daily is essential for preventing skin cancer and slowing signs of aging like wrinkles and dark spots. It may even help combat blue light damage from screens.Many people only think about sunscreen on vacation or during long afternoons at the pool. But Dr. Lam cautions that sun damage also happens in smaller, less obvious moments like:

Walking the dog
Running errands
Even driving in your car

That’s why dermatologists recommend wearing sunscreen every single day, no matter what you’re doing. Dr. Lam cautions that UV rays can harm your skin whether you burn or not–and once the damage is done, it can’t be undone. Sunscreen helps reduce this damage by absorbing or reflecting ultraviolet (UV) radiation, which includes:

UVA rays, historically associated with tanning and signs of aging
UVB rays, primarily associated with sunburns

But recent research shows the damage from UVA and UVB rays can go much deeper. A study published in the International Journal of Molecular Sciences found that both cause different types of serious damage, even without any visible sunburn. UVA rays trigger:

Inflammation
Collagen breakdown
Cell death

And UVB rays:

Disrupt skin cell behavior
Activate genes linked to cancer

The same study also found that raspberry extract, a natural antioxidant with mild SPF protection, helped reduce UV-related cell death. This confirms that sunscreen is about much more than preventing uncomfortable burns. Sunscreen is about protecting your body’s largest organ from deep, invisible damage that accumulates over time, potentially affecting your overall health.

How often to apply sunscreen

Even knowing why it matters, many people are still unclear on how often to reapply sunscreen–a key part of getting its full benefit. The general rule is:

Put on sunscreen 30 minutes before going outside.
Reapply it every two hours–or more if you’ve been swimming, sweating, and/or towel-drying.

This gives it time to absorb and ensures that you replace what’s been rinsed or rubbed off.Dr. Lam also recommends choosing a broad-spectrum SPF 30 or higher. SPF stands for Sun Protection Factor; it’s a measure of how well a sunscreen shields your skin from UVB rays. But don’t let higher numbers give you a false sense of security.“Sometimes what I see are people who use an SPF 50 will stay in the sun longer and won’t reapply,” she cautions. “They end up getting more sun damage, and it defeats the purpose.”No matter your SPF choice, reapply regularly, and be sure to use enough each time to get the level of protection promised on the label.

How much sunscreen to use

Whether you prefer a lotion or a spray, make sure you’re using enough sunscreen to get the full benefit.According to Dr. Lam, “On average, an entire body requires about an ounce or shot glass full for full coverage. A nickel-sized dollop is required for the entire face alone.” And if you’re using a spray, make sure to create an even sheen all over, and rub it in thoroughly. “Typically, a family of four should use one four-ounce bottle per person for a day-long event,” Dr. Lam adds.And don’t forget those often-missed areas, such as:

The tops of your ears
The back of your neck
Your scalp (especially where hair parts or thins)
Tops of your feet
Backs of your knees
Lips (you can use an SPF lip balm)

Do people of color need sunscreen?

It’s a common myth that people with darker skin don’t need sunscreen–and it is indeed a myth. While extra melanin does provide some natural protection, no skin tone is immune to UV damage or skin cancer.Again, UV rays harm the skin at a cellular level even without visible sunburn. That includes inflammation, collagen damage, and cancer-related gene activity, regardless of how easily you tan or burn.So layer on the sunscreen every two hours in the sun, every day–regardless of your skin tone.

Pair sunscreen with other sun safety strategies

Sunscreen is a must, but it works best as part of a bigger sun safety plan, Dr. Lam says. Be sure to pair it with other preventive measures like:

Wearing protective clothing, a wide-brimmed hat, and sunglasses
Seeking shade whenever possible
Avoiding direct sun between 10 a.m. and 2 p.m., when UV rays are strongest

“Shade isn’t a perfect shield,” Dr. Lam adds. “Some UV rays can still reach out, reflecting off water, sand, glass, concrete and snow.” That’s why combining multiple sun safety strategies is the best defense against long-term damage.