How to Apply Sunscreen Correctly & Protect Your Skin

Sunscreen is one of the best tools for protecting your skin from the sun’s harmful ultraviolet (UV) rays. Yet even people who use sunscreen regularly are unsure how to apply it and often miss important areas of the body.

“Sunscreen acts as a protective barrier between your skin and the sun’s ultraviolet rays, which can damage skin cells, leading not only to painful sunburns but also to premature aging and an increased risk of skin cancer,” says Columbia dermatologist Andrew Truong, MD. “Wearing sunscreen consistently is one of the most effective things people can do to protect their skin health.”

Dr. Truong explains which sunscreens to choose, how much we need, and the places where we are forgetting to apply.

How do you choose a sunscreen?

There are two main types of sunscreens:

• Mineral (physical) sunscreens contain ingredients such as zinc oxide or titanium dioxide, and they work by reflecting UV radiation off the skin.
• Chemical sunscreens contain compounds such as oxybenzone and avobenzone; they are more lightweight and work by absorbing UV rays before they can damage the skin.

Recently, the Food and Drug Administration approved the chemical bemotrizinol for use in sunscreens—the first new chemical sunscreen active ingredient approved in the U.S. in more than 20 years. Bemotrizinol is a more stable compound that is less absorbed into the body.

“This chemical has been used safely in Europe and other parts of the world for decades, and it provides stable, broad-spectrum protection against both UVA and UVB rays. Most importantly, it gives patients more options for finding a sunscreen they enjoy wearing every day,” says Dr. Truong.

Whichever type of sunscreen you choose, most dermatologists recommend using a product that is:

• Broad-spectrum, meaning it protects against both UVB rays (which are most responsible for sunburn) and UVA rays (which penetrate deeper into the skin and contribute to aging)
• SPF 30 or higher
• Water-resistant if you'll be swimming or sweating

What’s the right way to apply sunscreen?

Many people don't use enough sunscreen to achieve the SPF protection listed on the label. “You need to apply a generous amount,” says Dr. Truong.

For full-body coverage, adults generally need about 1 ounce of sunscreen—roughly enough to fill a shot glass.

Sunscreen should be applied about 15 minutes before going outside and reapplied every two hours when you’re outdoors—or more often after swimming or sweating. “Think of sunscreen as something that needs maintenance throughout the day, not a once-and-done application,” says Dr. Truong.

Another common misconception is that sunscreen is only necessary on sunny summer days. UV rays are present year-round and can penetrate clouds.

“Making sunscreen part of your daily morning routine, one you will use consistently, is one of the best habits you can develop for long-term skin health,” says Dr. Truong.

Where do people often forget to apply sunscreen?

Putting sunscreen on your face, arms, and legs may seem obvious, but many people forget to cover smaller areas.

"When we diagnose skin cancers, they’re often found in places people don't think about protecting, such as the ears, scalp, lips, back of the neck, and tops of the feet,” says Dr. Truong. “These areas receive a significant amount of sun exposure over a lifetime, so they deserve the same attention as your face and shoulders.”

When applying sunscreen, be sure to include:

• Ears: The tops, edges, and backs of the ears are among the most commonly missed spots. Because ears are exposed year-round, they’re especially vulnerable to sun damage.
• Eyelids: The skin around the eyes is thin and sensitive, but many people skip this area because they worry about irritation. A mineral sunscreen or sunscreen formulated for the face may be more comfortable.
• Scalp and hair part: People with thinning hair, short hair, or a visible part often overlook the scalp. Using sunscreen sprays or powders, or wearing a hat, can help protect this area.
• Lips: Lips can get sunburned, too. Look for a lip balm with SPF 30 or higher, and reapply throughout the day.
• Neck and chest: The neck and upper chest receive significant sun exposure but are frequently forgotten during daily routines. These areas are also common sites of visible sun damage and premature aging.
• Hands: Many people forget their hands, which are exposed to sun during everyday activities like driving, so they can accumulate substantial sun exposure over time.
• Tops of feet: Whether you’re at the beach or pool, or simply wearing sandals, the tops of your feet can burn quickly if left unprotected.
• Back of the neck: Even diligent sunscreen users often miss the back of the neck, especially if they apply sunscreen without assistance.

The Bottom Line

We know that cumulative sun exposure contributes to skin cancer risk over time. But the good news is that using sunscreen—in addition to wearing protective clothing, hats, and sunglasses, as well as seeking shade—can significantly reduce that risk.

“Small daily habits can make a meaningful difference over the course of a lifetime,” says Dr. Truong.

Andrew Truong, MD, is an adult and pediatric dermatologist and assistant professor of dermatology at Columbia.