Best sunscreen: Understand sunscreen options

Confused about the best sunscreen to use? Lawrence E. Gibson, M.D., a dermatologist at Mayo Clinic, Rochester, Minnesota, offers his guidance.

What are the best ways to protect yourself from the sun?

Focus on the big picture when it comes to sun safety. For example:

• Avoid the sun during peak hours. Generally, this is between 10 a.m. and 4 p.m. Water, snow, sand and concrete reflect light and increase the risk of sunburn.
• Wear sun protective clothing. This includes pants, shirts with long sleeves, sunglasses and hats.
• Use sunscreen. Look for water-resistant, broad-spectrum coverage with an SPF of at least 30. Apply sunscreen generously, and reapply every two hours — or more often if you're swimming or sweating.

What does a broad-spectrum sunscreen do?

There are two types of UV light that can harm your skin — UVA and UVB. A broad-spectrum sunscreen protects you from both.

UVA rays can prematurely age your skin, causing wrinkling and age spots. UVB rays can burn your skin. Too much exposure to UVA or UVB rays can cause skin cancer. The best sunscreen offers protection from UV light.

What SPF do you need?

SPF stands for sun protection factor, a measure of how well sunscreen protects against UVB rays. (UVA protection isn't rated.) Manufacturers calculate SPF based on how long it takes to sunburn skin treated with the sunscreen as compared to skin with no sunscreen.

Experts recommend using a sunscreen with an SPF of at least 30. Sunscreens with SPFs greater than 50 provide only a small increase in UV protection. High-number SPFs last the same amount of time as low-number SPFs.

Sunscreen is often not applied thoroughly or thickly enough, and it can be washed off during swimming or sweating. As a result, sunscreen might be less effective than the SPF number suggests.

What does water-resistant sunscreen do?

The term water resistant means that the SPF is maintained for up to 40 minutes in water. Very water resistant means the SPF is maintained for 80 minutes in water.

What do I need to know about sunscreen ingredients?

Sunscreens contain filters that reflect or absorb UV rays. There are two main types of filters:

• Organic. Organic filters absorb UV radiation and convert it to a small amount of heat. Examples include cinnamates, salicylates and benzophenones.
• Inorganic. Inorganic filters reflect and scatter UV radiation. Examples include titanium dioxide and zinc oxide. Inorganic sunscreens are typically less irritating to skin.

Sunscreens might also contain or be combined with:

• Insect repellent. Experts recommend using separate sunscreen and insect repellant products. Sunscreen needs to be applied generously and often, while insect repellant should be used sparingly and less frequently.
• Cosmetics. Some moisturizers, makeup and after-shaves contain sunscreen. While convenient, these products need to be regularly reapplied to continue providing protection.

Should I use a spray sunscreen or a lotion?

Consider the pros and cons for different applications, including:

• Creams. If you have dry skin, you might prefer a cream — especially for your face.
• Lotions. Lotions are often preferred for application on large areas. Lotions tend to be thinner and less greasy than creams.
• Gel. Gels work best in hairy areas, such as the scalp or chest.
• Stick. Sticks are useful when applying sunscreen around the eyes.
• Spray. Sprays are easy to apply on children. Because it's difficult to know how well you're applying it, spray a generous and even coating. To prevent inhalation of the product, don't spray near the face or mouth. Check the direction of the wind before spraying.

What else do I need to know about sunscreen?

When you use sunscreen:

• Apply generous amounts of sunscreen to dry skin 15 minutes before you go outdoors.
• Use sunscreen on all skin surfaces that will be exposed to the sun, such as your neck, the tops of your feet, your ears and the top of your head. Apply a lip balm or lipstick with an SPF of least 30 to your lips.
• Since UV light can pass through clouds, use sunscreen even when it's cloudy.
• Check the sunscreen's expiration date.
• Avoid using sunscreen on children younger than age 6 months. Instead, try to limit sun exposure.

Use sunscreen year-round, but don't let any product lull you into a false sense of security about sun exposure. A combination of shade, clothing, sunscreen and common sense is your best bet.