Does Sunscreen Work? How SPF Protects Your Skin

Does Sunscreen Really Work?

Yes. Sunscreen is one of the best ways to protect your skin from the sun’s harmful ultraviolet (UV) rays. It helps prevent sunburn, lowers your risk of skin cancer, and reduces signs of early skin aging like wrinkles and dark spots.

Not by much.

Many people assume SPF 100 provides twice as much protection as SPF 50, but that’s not how SPF works.

• SPF 30 blocks about 97% of UVB rays.
• SPF 50 blocks about 98%.
• SPF 100 blocks about 99%.

That small increase usually isn’t enough to make a meaningful difference for most people. What matters most is using enough sunscreen and reapplying it often.

What SPF Should You Use?

For most adults and children, a broad-spectrum sunscreen with SPF 30 to 50 provides excellent protection.

Choose a sunscreen that is:

• Broad-spectrum (protects against UVA and UVB rays)
• SPF 30 or higher
• Water resistant if you’ll be swimming or sweating

No sunscreen can block 100% of the sun’s rays, so it’s important to use other forms of sun protection too.

Sunscreen Works Best When You Use It Correctly

To get the most protection:

• Apply sunscreen about 15 to 30 minutes before going outside.
• Reapply every two hours.
• Reapply after swimming or heavy sweating, even if the product is water resistant.
• Cover all exposed skin, including your ears, neck, hands, and feet.
• Check the expiration date and replace old sunscreen.

Don’t Rely on Sunscreen Alone

Sunscreen is only one part of protecting your skin.

You can lower your risk of sun damage by:

• Staying in the shade during the middle of the day.
• Wearing a wide-brimmed hat.
• Choosing lightweight clothing that covers your arms and legs.
• Wearing sunglasses that block 100% of UVA and UVB rays.

These simple steps help reduce your exposure to harmful UV rays and lower your risk of skin cancer.

Who Needs Extra Sun Protection?

Some people are more likely to develop skin cancer or sun damage and should be especially careful in the sun.

You may need extra protection if you:

• Have had skin cancer before.
• Have a family history of skin cancer.
• Have very fair skin or burn easily.
• Have a condition such as albinism or xeroderma pigmentosum.
• Have a weakened immune system.

Talk with your doctor if you’re unsure how to protect your skin or if you notice a new or changing mole, sore, or skin spot.

Protect Your Skin Year-Round

Sun damage can happen in every season, not just during the summer. Making sunscreen part of your daily routine can help protect your skin for years to come.

If you have questions about sun safety, need a skin evaluation, or want to establish care with a primary care provider, Grady’s primary care physicians are here to help. Book your appointment online at gradyhealth.org, through MyChart, or call (404) 616-1000. With convenient locations across metro Atlanta, you’ll have access to expert primary care and Grady’s full network of specialty services.

Continue Your Health Journey

Want to learn more about staying healthy? Visit Grady’s Health Library for trusted, physician-reviewed information on symptoms, diseases, preventive care, medications, wellness, and more. Whether you’re managing a chronic condition or looking for healthy lifestyle tips, you’ll find reliable resources to help you make informed decisions about your health.