Containers of sunscreen.

Everyone has heard about the link between sun exposure and skin cancer, and the need to cover up and use sunscreen. But most consumers aren’t up to speed on even the simplest of sunscreen basics, according to the latest research.

A recent study published in the Journal of Clinical and Aesthetic Dermatology, for example, found that less than half of nearly 300 dermatology patients knew when to apply sunscreen before going outside (15 to 30 minutes); how often to reapply it (every 2 hours or after sweating or swimming); and how much is needed to cover the entire body (about an ounce).

This lack of knowledge is especially worrisome because sunscreen is one of the best defenses against sunburn, a major risk factor for skin cancer, the most common type of cancer in the U.S. And considering that another recent study found that about a third of Americans get sunburned each year, knowing how to properly use sunscreen is as important as ever.

Here, then, your most common sunscreen questions, answered. 

1. How Does Sunscreen Work?

Sunscreens are formulated with ingredients that shield your skin from harmful ultraviolet A (UVA) and ultraviolet B (UVB) radiation, which can cause skin changes that contribute to skin cancer and aging. The ingredients do this by reflecting or absorbing those rays.

SPF, or sun protection factor, is a measure of how well a sunscreen shields against UVB rays, the main contributor to sunburn. The Food and Drug Administration (FDA) requires all sunscreens to carry an SPF number.

Some sunscreens shield against just UVB rays, and some protect against both UVA and UVB. Called “broad spectrum” sunscreens, those that shield against both types of UV rays offer the best sun protection.  

2. Is a Higher SPF (Like 50) Always Better?

The American Academy of Dermatology (AAD) says the best sunscreen provides broad-spectrum protection, is water-resistant, and has an SPF of at least 30.

More on Sun Safety

Higher SPFs don’t provide all that much additional protection. Going from an SPF 15 (which screens out 93 percent of UVB rays) to a 30 (which screens out 97 percent) makes sense. An SPF 50 blocks just a bit more—98 percent of UVB. Even an SPF 100 only shields you from 99 percent of UVB rays.

Relying on high SPFs may actually lead to more sunburns, some experts say, because consumers may feel a false sense of security and reapply less often. People tend to think that a higher SPF means you can stay out in the sun longer without reapplying, but no matter what SPF you choose, you need to reapply every 2 hours. 

Because of this, the FDA has been considering since 2011 whether to limit the highest SPF on a sunscreen to "50+." According to the agency, "there is not sufficient data to show that products with SPF values higher than 50 provide greater protection for users than products with SPF values of 50.” 

Still, some experts believe that using higher SPFs may be worthwhile. That's because most people don’t apply the correct amount of sunscreen (an ounce to cover your entire body) often enough. Studies suggest that putting on only half the recommended amount, or a half-ounce, could decrease a sunscreen’s SPF by about one-third to one-half. So a higher SPF would offer more protection when people don't use enough sunscreen.  

3. Is a Mineral Sunscreen Better Than a Chemical One?

Mineral sunscreens—which typically contain such ingredients as titanium dioxide, zinc oxide, or both—protect against UV rays by deflecting them. (For this reason, they are technically called physical sunscreens.) Chemical sunscreens—which contain such ingredients as avobenzone or oxybenzone—absorb UV light.

In the past six years of sunscreen testing, Consumer Reports hasn’t found a mineral product that offers both top-notch UVA and UVB protection, says Susan Booth, the project leader for our sunscreen testing. So while a mineral sunscreen provides some protection, if you trust your skin to one of these products, you could be getting more UV damage than you think.  

CR has found that the SPF value of many sunscreens (both the mineral and chemical kind) in our tests varies from the SPF printed on the package.

For this reason, Consumer Reports recommends choosing a sunscreen that performed well in our ratings. If you can’t find one, choose a broad-spectrum chemical sunscreen with an SPF of 40 or higher. That will give you the best chance of getting at least an SPF 30. 

4. Do I Need to Wear Sunscreen if I Have Darker Skin?

Yes. It’s true that people with fair skin are at greater risk of skin cancer than those with darker skin. But UV rays can damage any type of skin, so it’s important to wear sunscreen no matter what your skin color or ethnicity.

If you have a darker tone and want a sunscreen that won’t leave a white cast on your skin, try Banana Boat SunComfort Clear UltraMist Spray SPF 50+, which received an excellent score in CR’s test for overall sun protection, and won’t leave you with white streaks. 

5. Is Sunblock Different From Sunscreen?

“Sunblock” is a term you should no longer see on sunscreens. In 2011, the FDA banned sunscreen manufacturers from using the phrase on labels because it offers a false sense of protection.

“There's nothing that blocks the sun,’” says Roopal V. Kundu, M.D., an associate professor of dermatology at the Northwestern University Feinberg School of Medicine. “There's only sunscreen.”

If you do see this phrase, the sunscreen either may have been manufactured in a different country or is a bottle from pre-2011 and should be tossed. (See question no. 10, below, on sunscreen expiration dates.) 

6. What's the Best Sunscreen for Babies?

You shouldn't use sunscreen on babies younger than 6 months. Sunscreen ingredients are not only irritating to a baby's delicate skin, says Kundu, but their skin is also particularly sensitive to sun at that age, so they should avoid direct sunlight as much as possible. 

Experts recommend keeping young infants in the shade or under an umbrella. And use hats and cover them up with clothing, rash guards, and sunglasses instead of sunscreen.

For older babies and kids, you might think that a sunscreen  specifically labeled for them has stronger sun-shielding properties than those marketed to adults. But while their packaging and scent might be a little different, their effectiveness is exactly the same, says Kundu. A child can use an adult sunscreen and vice versa.

Dermatologists often recommend physical (i.e., mineral) sunscreens such as titanium and zinc formulas for children and people with sensitive skin. However, as noted earlier, CR hasn’t found a mineral product that offers both top-notch UVA and UVB protection.

If you want a mineral sunscreen for your kid in spite of this, we suggest California Kids #Supersensitive Lotion SPF 30+ or Badger Active Unscented Cream SPF 30. (Both received a Good overall score in our test, though Badger offers better UVA protection and California Kids is better with UVB.) 

7. Is Sunscreen Bad for the Environment?

Research in the past few decades has found that sunscreens containing certain chemical ingredients, such as oxybenzone and octinoxate, contribute to coral bleaching, a condition that leaves coral vulnerable to infection and prevents it from getting the nutrients it needs to survive.

Even if you're not at the beach, the sunscreen on your body might still end up in the ocean. Sunscreen can get into the water system after you wash it off in the shower.

How best, then, to protect your skin and the environment?

Mineral sunscreens with zinc oxide or titanium dioxide appear to be safer for coral reefs than chemical ones, according to the National Park Service. But, as previously noted, CR testing hasn’t found any mineral sunscreens that offer top-rate protection.

Another option is to cover up with UPF (ultraviolet protection factor) clothing, says Craig A. Downs, Ph.D., executive director of the Haereticus Environmental Laboratory, a nonprofit scientific research organization. You’ll still want to apply sunscreen to exposed skin, but you’ll need far less—up to half the amount, Downs says—than you would if you were in a bathing suit.

If you still want a chemical sunscreen but prefer one that’s oxybenzone-free, the two highest-scoring such spray and lotion sunscreens in CR’s most recent test were Well at Walgreens Moisturizing Lotion SPF 50 and Hawaiian Tropic Island Sport Ultra Light Spray SPF 30

8. What’s Better—a Spray or Lotion?

Both are equally effective. Where it gets tricky is in how they’re applied. To cover your entire bathing-suit-clad body, you need about an ounce—or a shot-glass-full—of sunscreen. This is easy to measure with a lotion, but more complicated with a spray.

For sprays, the best way to ensure you’re getting enough is to spray it liberally on your skin, then rub it in evenly with your hands. Avoid applying where it's windy, because you might lose some of your sunscreen to the air.

There has been some concern about the safety of sprays. The FDA has said it is exploring the risks of inhaling spray sunscreens. Until we know more, Consumer Reports’ experts say to avoid using sprays on children, and don't spray directly on your face. Instead, spray sunscreen onto your hands, then apply it to your face. If you do use a spray on a child, spray the sunscreen into your hands and rub it onto the child’s skin.

Sprays may also contain flammable ingredients, such as alcohol, so you should never apply them near an open flame, according to the FDA. 

9. Does Sunscreen Expire?

Sunscreen is formulated to remain effective for at least three years, according to FDA regulations. Any bottle older than that isn’t guaranteed to protect you.

If you find an old bottle at the bottom of last summer’s beach tote and can’t remember when you bought it, check the expiration date. If there isn’t one, play it safe and buy a new bottle, then scribble the purchase date on the new container with a permanent marker.

Remember, too, that even with a new bottle, heat can speed up its breakdown. So keep your sunscreen out of direct sunlight and avoid storing it in places where the temperature can spike, such as in your car. When you’re out in the sun, the FDA recommends swaddling it in a towel or stashing it in the shade or even a cooler. 

10. What Does the Word 'Organic' Mean on Sunscreen?

It's meaningless. Unlike the “organic” label on cereal, for example, which means that at least 95 percent of its ingredients are USDA-certified organic, the FDA—which regulates sunscreens—doesn't have a definition for "organic," nor does it regulate the term. So sunscreens with it on their packaging aren’t guaranteed to contain organic ingredients. 

11. Can You Use Moisturizer With SPF Instead of Sunscreen?

You can, but it may not protect you as much as you think it will. Many daily moisturizers with sunscreen contain only an SPF 15 and may not be broad-spectrum. (Check the label for that term.)

And you probably aren’t applying enough moisturizer to reach the SPF listed on the bottle anyway. The general rule of thumb is that you need about 1 teaspoon of sunscreen to cover your entire face. A dab of moisturizer probably won’t cut it.

The same goes for makeup. A dusting here and there with a powder with SPF, for example, isn’t going to cover your face evenly. Applying enough to be effective would mean you'd have to cake it on, likely the opposite effect you’re going for.

Additionally, as with all sunscreen, you need to reapply it at least every 2 hours. For many people, applying moisturizer or makeup is a once-a-day affair. 

12. Do You Need Sunscreen in the Car?

Yes. Windshields made from laminated glass block almost all UVB rays and 98 percent of UVA rays, but 79 percent of skin-damaging UVA rays can pass through side and rear window glass. So apply sunscreen if you’re going to be in a car—no matter what time of year it is. 

13. Do Sunscreen 'Pills' Work?

Nope. As the FDA said in a recent statement, “There’s no pill or capsule that can replace your sunscreen.”

In late May, the FDA sent warning letters to several supplement makers for including unproven sun-protection claims on the capsules they promoted on their websites. These included misleading statements that their products would “strengthen your skin’s defenses against ultraviolet radiation” or provide “broad-spectrum” protection." One customer review said, “[i]t’s basically an oral sunscreen … This would be especially useful for people who have had skin cancer, are at risk for skin cancer ... ”

Instead of relying on a supplement for sun protection, use sunscreen along with other sun-avoidance strategies, such as seeking shade on sunny days and wearing sun-protective clothing such as hats, long sleeves, sunglasses, and long pants.