Top 10 myths about sunscreens

Sunscreen is essential for protecting your skin from early aging and skin cancers, which often are a direct result of the sun's ultraviolet, or UV, radiation.

Even with increased awareness of dangers from the sun, more people in the U.S. are diagnosed with skin cancer each year than all other cancers combined. By age 70, at least 1 in 5 people in the U.S. will develop skin cancer.

It's more difficult to treat wrinkles, sunspots and leathery skin once the damage is done, so prevention is key.

Check out the top 10 myths about sunscreen before you venture outdoors:

Myth #1: It doesn't matter what time of day I go out in the sun.

Fact. In North America, the sun is at its peak between 10 a.m. and 4 p.m. That's when UV rays are strongest and your risk of skin damage is the greatest. However, this doesn't mean early mornings and late afternoons are without risk. You need skin protection from sunrise to sunset.

Myth #2: I can't get sunburned or suffer skin damage when it's cloudy, rainy or during the winter.

Fact. If the sun is up and you're outdoors, you're exposing your skin to UV radiation. Even on cloudy days, up to 90% of the sun's rays still can penetrate your skin. Water, sand and snow can reflect the sun, which exposes your skin to indirect UV rays. No matter the weather or the season, applying sunscreen every day is a must.

Myth #3: I tan but don't burn, so I don't need sunscreen.

Fact. There is no such thing as a safe tan. Tanning is your body's response to UV damage and a sign that your skin has been injured. Even getting just a "glow" damages your skin's DNA, and increases aging and your risk of skin cancers. A tan will not protect your skin from sunburn or other sun damage.

Myth #4: I don't need sunscreen because I have dark-colored skin.

Fact. Dark-colored skin does not burn as quickly, although it still is susceptible to sun damage, including dark spots, wrinkles and sunburn. Regardless of your skin tone, do not skip the sunscreen.

Myth #5: My makeup has sunscreen. That's all I need.

Fact. Foundation with a sun protection factor, or SPF, of at least 30 provides some sun protection, but is less protection than traditional sunscreen. Also, most people typically apply makeup to just the face, and not the throat, back of the neck or other sun-sensitive areas. Be sure to apply a layer of traditional sunscreen under your foundation, as well as any areas that will be exposed to the sun.

Myth #6: I won't get enough Vitamin D if I wear sunscreen.

Fact. Even well-applied sunscreen lets 2% to 3% of the sun's ultraviolet B rays reach your skin, and your body needs only a little to produce vitamin D. Rather than risk skin cancer, it's better to seek your vitamin D needs through a healthy diet or supplement.

Myth #7: Any kind of clothing protects my skin from getting too much sun.

Fact. Darker, heavier fabrics with tighter weaves offer more protection than lightweight and light-colored clothing. You also can get high-tech protection and breathability from many new fabrics. Look for the ultraviolet protection factor, or UPF, designation on apparel. A UPF of 30 to 49 offers good protection, while a UPF of 50 or more rates as excellent. The more skin you cover, the better. Don't forget to accessorize your outfit with a wide-brimmed hat and UV-filtering sunglasses.

Myth #8: A higher SPF gives significantly more protection.

Fact. No sunscreen blocks 100% of the sun. Sunscreen with an SPF of 100 blocks only 1% to 2% more of the sun's rays than one with an SPF of 30, which already blocks 97% of rays. Also, SPF does not affect how long you will be protected. Protection typically lasts two hours or less for all sunscreens. Look for a broad-spectrum — blocks UVA and UVB rays — water-resistant sunscreen with an SPF of at least 30. Reapply it frequently, especially after being in the water or sweating.

Myth #9: All sunscreens are created equal.

Fact. Not necessarily. There are two primary types of sunscreen: physical and chemical. Both options have pros and cons.

Physical sunscreens, also called mineral sunscreens, work like a shield and sit on the surface of your skin to deflect the sun's rays. They contain the active ingredients zinc oxide or titanium dioxide. Mineral sunscreens are considered safer for you and the environment. They also are best for people with sensitive skin, children and those with pigment concerns, such as melasma. While traditional mineral sunscreens left a white residue on your skin, tinted and less-visible mineral sunscreens now are available.

Chemical sunscreens work like a sponge. They absorb the sun's rays into the skin and convert the UV light into heat, which then dissipates. In the U.S., these sunscreens contain one or more of these active ingredients: oxybenzone, avobenzone, octisalate, octocrylene, homosalate and octinoxate. Chemical sunscreens are easier to apply and don't leave a white residue on the skin. However, they can irritate the eyes and cause allergic reactions on some people's skin.

If possible, avoid sunscreens with oxybenzone because this chemical may disrupt hormones and cause allergic skin reactions. Also, pass on spray sunscreens, which are not nearly as effective as those applied by hand.

Also avoid so-called sunscreens, such as cocoa butter, safflower, olive, jojoba, baby or coconut oil that provide no sun protection.

Myth #10: Sunscreen never goes bad.

Fact. The Food and Drug Administration requires that all sunscreens retain their original strength for at least three years. Check the bottle for an expiration date. If your sunscreen has expired or been exposed to extreme heat or cold, toss it. If you're using sunscreen every day when outside, a bottle should not last long.

Melanie Dixon, M.D., practices family medicine, with a special interest in dermatology, in Mankato, Minnesota.