Everything You Need to Know About Zinc Oxide and Your Sunscreen

You may have seen the ingredient “zinc oxide” on everything from your sunscreen bottles and calamine lotions to makeup products and even acne treatments, but do you really know what it really is—or does? Technically, it is all-natural, occurring as the mineral zincite, but it can also be produced synthetically or through chemical processing by human agency. Its most common and notable use is as a sunscreen agent, which it is FDA-approved for.

“As a mineral-based sunscreen active ingredient, zinc oxide reflects light off the surface of the skin where the sunscreen is applied back into the environment, much like a mirror,” says Melanie D. Palm, M.D., San Diego–based dermatologist, cosmetic surgeon and founding director of Art of Skin MD.

“Zinc oxide can be ‘micronized,’ meaning it’s processed into very small particles, so small that the preparation appears clear when applied on the skin.” Non-micronized formulations, she explains, are often less cosmetically elegant and are more opaque or white. So, if you’ve ever applied a sunscreen that left a white, powdery cast on your body, it most likely contained zinc oxide as a key ingredient.

To help you further understand how this mineral plays a key role in your skin care regimen, especially in the sun-protection department, here are some commonly asked questions answered by top dermatologists.

How does zinc oxide work compared to other sunscreen ingredients—and is it safe?

Zinc oxide isn’t the only sunscreen ingredient used to block harmful UVA and UVB rays. Many sunscreens contain an ingredient called titanium dioxide, which, like zinc oxide, is typically found in mineral sunscreens. It’s also considered safe since it does not penetrate the skin and offers broad-spectrum protection against both UVA and UVB rays. Although, Francesca Fusco, M.D., dermatologist at Wexler Dermatology in New York City, points out that some studies have shown that titanium dioxide can work as a photosensitizer that can be absorbed by the skin. “A safe bet is to look for sunscreens that are known to use particles too big to be absorbed, or those containing zinc oxide, which is the safest ingredient according to the Environmental Working Group (EWG).”

Still, all four common sunscreen ingredients—mineral-based zinc oxide and titanium oxide and chemical-based avobenzone and mexoryl SX (ecamsule)—have been shown to be non-toxic when used on the skin and to not break down when exposed to the sun, which is vital. “Titanium and zinc oxides are the best options on this list as they both block and protect against all UVA rays, whereas the other two don’t provide as much protection,” adds Dr. Fusco.

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What are some pros and cons of using zinc oxide?

Pro: It protects against both UVA and UVB rays.

Surprisingly, not all sunscreens protect against both UVA and UVB rays. Zinc oxide, however, does. “It’s a photostable, broad-spectrum sunscreen, so it has one of the broadest UVA coverages of all the sunscreen ingredients currently available in the U.S, as well as UVB coverage,” says Sejal Shah, M.D., dermatologist and contributor to the cosmetic treatment site RealSelf.

Con: It goes on white.

When applied, zinc oxide–containing sunscreens appear white on the skin, so they give a translucent, almost ghost-like appearance. This makes it especially difficult for use on patients with darker skin types. “When you use higher concentrations to achieve high SPF values, the formulas are often tinted to mask the white discoloration it would leave on the skin otherwise,” says Joshua Zeichner, M.D., director of cosmetic and clinical research in dermatology at Mount Sinai Medical Center.

Pro: It works right away.

You’ve probably been told to wait at least 20 minutes between applying sunscreen and actually going outside to be in the sun. While this is true for some sunscreens, it is not necessary when using brands containing zinc oxide. “Because it is a physical blocker, it works as soon as you apply it, so technically it does not need to applied 15–30 minutes before sun exposure, as a chemical sunscreen does,” explains Dr. Shah.

Con: In rare cases, it could cause an allergic reaction.

While zinc oxide is considered to be non-sensitizing and non-comedogenic, in rare cases it could cause a minor allergic reaction, according to Dr. Fusco.

Pro: It’s great for all skin types.

Since zinc oxide is used as a skin protectant, it rarely causes irritation on the skin, according to Dr. Zeichner. For this reason, it can be used on any skin type—even on those with extremely sensitive skin. It is also non-comedogenic for the most part, which means it is very likely to cause breakouts or acne.

Who is zinc oxide best for?

Basically, everybody. Anyone older than six months can use physical sunscreens that contain zinc oxide. “Sensitive-skin patients, rosacea patients and acne patients all benefit from the anti-inflammatory properties of zinc oxide,” adds Dr. Palm. “Additionally, patients with skin discoloration, including melasma, will benefit, not only from zinc oxide’s ability to block not only UV light, but also to block out visible and infrared light while not producing heat, which can aggravate pigmentary problems.”

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Ready to use zinc oxide? Here, Dr. Palm shares some dos and don’ts:

Do: Re-apply as necessary.

Check to see if the formulation is water-resistant and re-apply every 40–60 minutes as indicated by labeling.

Don’t: Apply zinc oxide once you’re outside.

By then it can be too late. It’s better to apply sunscreen while you’re still indoors, even though zinc oxide works rather quickly.

Do: Choose a more cosmetically elegant formation.

Clear zinc oxide formulations are well-tolerated, and many, if you choose, have tint and can be used as a makeup primer.

Don’t: Forget to apply sunscreen everywhere.

Hands, neck and chest are frequently forgotten areas that need sunscreen. Even minutes of exposure daily over a lifetime add up to unwanted UV exposure that can lead to skin changes and even increased incidence of skin cancer.

Do: Use the right amount.

A proper full body application requires 1-ounce ( a shot glass) for proper coverage. Most of us underapply by about 50 percent.

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