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.
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.
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. 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.
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.
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.
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.
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.
Pro: It’s great for all skin types.
Since zinc oxide is used as a skin protectant, it rarely causes irritation on the skin. 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 unlikely 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. 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.