How Much SPF is Enough for Me?

A woman on a beach wearing sunscreen on her nose and touching her nose with her index finger.

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We’re entering the summer months: the time of year when outdoor activities like swimming, biking and playing in the yard take center stage. And while soaking in some vitamin D and staying physically active is certainly good for you, it’s easy to get burned if you don’t protect yourself from the sun’s harmful ultraviolet (UV) rays. That’s why grabbing that bottle of sunscreen before heading out the door is critical — as is knowing how much of it you need.

SPF 101

SPF (sun protection factor) refers to protection against the sun’s UVB rays, which are the type of rays in the UV spectrum that cause sunburn and play a large role in the development of skin cancer. The SPF number on sunscreen packaging is a measure of how much UVB protection it provides. Specifically, the number tells you how long the sunscreen will protect your skin from burning. For example, if you have sunscreen with an SPF of 15, you’ll need to reapply in 15 minutes to avoid sunburn.

While it’s true that the higher the number, the more protection it provides, the downside of high-SPF sunscreen is that it may give you a false sense of security if you choose a sunscreen with a higher SPF, believing you can stay out in the sun longer.

The other type of rays in the UV spectrum are UVA rays. They can also cause skin damage. The phrase “broad spectrum” on a product’s label means the sunscreen protects against both UVB and UVA rays.

No matter what, though, you shouldn’t rely on broad-spectrum SPF alone to protect you from the sun. Instead, you should use sunscreen as part of a larger sun-defense strategy. For example, take preventive measures like wearing a hat, sunglasses or other protective clothing — and seeking shade whenever possible — to help defend yourself from UV rays.

Mineral vs. Chemical Sunscreen

Another important thing to know about sunscreen is that it’s usually made from mineral ingredients or chemical ingredients. Mineral sunscreens — also known as physical sunscreens — create a physical barrier on the skin that shields it from the sun’s UV rays. Chemical sunscreens work by absorbing UV rays before they’re soaked up by the skin.

Dermatologists typically recommend mineral options because chemical sunscreens can cause health risks related to endocrine function and possible skin reactions. (Learn more about physical and chemical sunscreens.)

Choosing the Best Sunscreen

The choice of which type of sunscreen to use, as well as which SPF you’ll need, often depends on how long you’ll be outside and on your skin tone. If you have fair skin that burns easily, you’ll likely want to reach for sunscreen with a higher SPF, even if you won’t be in the sun long. Similarly, if you have dark skin that rarely burns, you’ll probably be fine with a lower SPF for a short stint in the sun.

Just remember that reapplying is vital — and while many sunscreens are water resistant, none are completely waterproof. That means you should reapply after any exposure to sweat or water. (And it’s why most dermatologists recommend using a water-resistant, broad-spectrum sunscreen with an SPF of 30 or higher for any extended outdoor activity.)

Your Call for Dermatology Care

If you have are concerned about your skin, we’d love to talk with you. We offer comprehensive services for people of all ages. We’ll treat your condition or help ensure your skin stays healthy with the latest technological advances and compassionate care. And we’ll tailor our treatment to your needs and circumstances — because our main goal is to help you feel your best.

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