Do non-chemical sunscreens, which rely on mineral-based physical barriers such as zinc oxide or titanium dioxide, do a good job? Or should you rely on “chemical” sunscreens that absorb into your skin and then absorb, rather than block, the sun’s rays?

It’s an ongoing debate. Many consumers avoid chemical sunscreens because some of their ingredients—oxybenzone is the most notorious—have been linked to hormonal disruption, skin allergies and possible cancer risk. Some are also linked to environmental harm—in fact, Hawaii recently passed a law banning oxybenzone as well as another common ingredient, octinoxate—both of which harm fragile coral reefs—from any sunscreen products sold in that state.

But in its testing, Consumer Reports has rated mineral sunscreens as less protective than chemical ones.

What’s the best, safest sunscreen protection for you this summer? To sort this out, we interviewed Steven Q. Wang, MD, director of dermatologic surgery and dermatology at Memorial-Sloan Kettering Cancer Center in Basking Ridge, NJ.

The Great Sunscreen Debate

If you’ve been using a mineral sunscreen, Consumer Report’s 2018 ratings (subscription required for full report) of 73 sunscreens may raise alarm bells. Based on its testing, CR doesn’t recommend any mineral sunscreens, which means none were judged to provide “excellent” or “very good” protection from both UVA and UVB radiation—although five got excellent scores for UVA protection. Only sunscreens with chemical ingredients that absorb into the skin have garnered the highest ratings.

You may be thinking, So are chemical sunscreens the only ones that work? The answer is no. For one thing, not all mineral sunscreens do poorly in the CR ratings—some were rated as “good.” For another, in its 12th Annual Sunscreen Guide, the Environmental Working Group, a non-profit that examined almost 650 sunscreen products, found that mineral products did well, offering good protection from UVA and UVB radiation without potentially harmful additives. It’s difficult to evaluate the different methodologies that led to these discrepancies in rating mineral sunscreens.

But even if the Consumer Reports methodology is sound (and I have no reason to assume that it’s not), I believe that even “good” protection is all you need—but only if you use your sunscreen right. That is my experience with my patients—and in my own testing of sunscreens.

Most of us don’t use sunscreen the right way, if we use them at all. And that’s a much bigger factor than which kind of sunscreen you choose in determining whether you’re protecting yourself from damaging sun radiation that can accelerate skin aging and increase skin cancer risk.

What’s more important than which type of sunscreen? Remembering to put it on in the first place, using it correctly—most people don’t—and realizing that you can’t rely on sunscreen alone to protect your skin. That last point is the most important one: Your first line of defense should be other forms of protection: hats, clothing, seeking out shade and avoiding the mid-day sun. That advice goes for both adults and children.

The truth is, most of us don’t use sunscreen at all when we need it. The Centers for Disease Control & Prevention has found that fewer than 15% of men and 30% of women regularly put on sunscreen when they are outdoors for more than an hour. And a recent study published in the Journal of Clinical and Aesthetic Dermatology found that fewer than half of 294 dermatology patients—who, presumably, are likely to be more informed than people who don’t see dermatologists—knew when to apply sunscreen before heading outdoors, how much to put on, and how often they needed to reapply it. Another study found that people who use sunscreen are more likely to get sunburned than those who don’t use it—perhaps because they assumed the sunscreen “allowed” them to remain out in the sun longer than it actually did.

My Rules for Sunscreen Use

The following simple strategies should help you successfully protect your skin from sun damage…

  • Gear your sunscreen use to where you will be and what you will be doing. If you drive to an office and work indoors, for example, and then go out briefly for lunch, you need only an SPF 30 sunscreen that you apply once to your face (women should put it on under makeup), neck and exposed areas of your arms. An SPF 30 product is also fine if you’re spending more than an hour outdoors. But if you will be outdoors swimming, hiking, playing sports, etc., use an SPF 50 or higher sunscreen that’s water resistant, and apply it to all of your exposed skin. Tip: Don’t assume that all mineral sunscreens are water-resistant—some are, others aren’t, so check labels.
  • If you’re using a chemical sunscreen, apply it 15 to 30 minutes before you go outdoors. Mineral sunscreens are effective the moment you put them on, but chemical sunscreens need time to be absorbed to take effect.
  • Reapply sunscreen every two hours. This is true for everyone, but it’s especially important if you’re sweating or swimming.
  • Don’t worry about the exact amount you apply. Studies show most people don’t use enough sunscreen. If guidelines like “one shot glass” or “one teaspoon” are confusing, simply apply sunscreen twice. Like painting a house, you often miss spots (ears, tops of feet, areas of your back) when you apply the first “coat.” The second application helps make sure you cover those missed areas and put on enough to really protect yourself.

So choose the sunscreen that you prefer—and then take the steps above to make sure that it’s really protecting you.