Six Myths About Mineral Sunscreen, and Why They're Wrong
Mineral sunscreens, made with titanium dioxide or zinc oxide, are becoming a popular alternative to more traditional sunscreens. Unfortunately there are a lot of misconceptions about how mineral sunscreens work, and whether they are better than chemical sunscreens. Let’s dispel a few of those myths.
What is the difference between mineral, physical, and chemical sunscreens?
Mineral or “physical” sunscreens are made with tiny particles of titanium dioxide or zinc oxide. Chemical sunscreens include pretty much everything else: oxybenzone, octisalate, and others.
The term “physical sunscreen” comes from a misconception (more about that in a minute) that these ingredients physically block the sun. Mineral sunscreens, as I’ll call them throughout this article, are the ones that go on with a bit more of a white appearance (unless they are tinted) and are more often common in sunscreens marketed for kids or that bill themselves as a “natural” alternative.
There are also sunscreens that combine both types of ingredients.
Myth: mineral sunscreens are “sunblocks”
Wow, no. No substance in a bottle blocks the sun, and that’s why the FDA has banned the word “sunblock” from sunscreen labels and ads.
There’s a myth running around on the internet that chemical formulations can only be sunscreens but mineral ones are sunblocks. That’s not true and was never true. Both are sunscreens.
You can use the term “sunblock” if you like (since the FDA only regulates company marketing, not casual speech), but it’s a synonym for sunscreen, not a completely different product. Sunscreen and sunblock are the same thing, and it comes in both mineral and chemical formulations.
Myth: mineral sunscreens reflect UV rays, while chemical sunscreens absorb them
This may seem like a pedantic point, but this misconception leads to further misconceptions, like the one above assuming that mineral ingredients “block” the sun.
In actuality, both chemical and physical sunscreens work by absorbing ultraviolet light. Scientists used to think that titanium dioxide and zinc oxide worked by reflecting UV rays, but this isn’t the case. We’ve known since 2015 that mineral oxides mostly absorb UV, and only reflect a tiny bit.
Myth: With mineral sunscreen, you can go into the sun right after applying
Mineral and chemical sunscreens are the same when it comes to the standard “wait 15 minutes after applying...” advice. In both cases, the sunscreen starts working right away. It doesn’t need to absorb into your skin to become effective.
What does matter is making sure that the cream or spray has fully dried, so that it has some resistance to rubbing off against your clothes (or furniture, etc). Drying also ensures that it won’t run off the minute you step into the pool or start sweating.
Myth: mineral sunscreen is a drop-in replacement for your old favorite chemical sunscreen
This one is partially true—you can get good protection against the sun’s rays from a mineral as well as a chemical sunscreen. But chemical sunscreens are often easier to use in a way that achieves the labeled SPF.
This summer, my husband bought his usual favorite sunscreen for our vacation—a spray from Trader Joe’s—but it had been reformulated to use mineral rather than chemical ingredients. It performed very differently.
First, it went on white, not clear, and took a lot of rubbing-in to make sure we didn’t look pale and pasty. Some of us applied it thinly and probably got less protection; some of us laid it on thick and looked like ghosts. It also took longer to dry on the skin, which was bad news for those of us who couldn’t wait to swim. I remember seeing my husband get in the pool with his face covered in white sunscreen (“I don’t care,” he said about his appearance) and it ran down his face as he swam.
He ended up with sunburn on his face. The kids also ended up with some sunburn on their shoulders, so I bought sun shirts for them and paid more attention to how we were applying the sunscreen to their faces. They were fine for the rest of the trip, but man, I missed the old formulation, chemicals and all.
This is not to say that mineral sunscreens will always perform poorly. But depending on the formulation, they may have some disadvantages compared to chemical sunscreens. You may need to apply them more thickly, for example, but of course this will vary from brand to brand. Pay attention if you’re switching products.
Myth: you can make your own mineral sunscreen
It’s not easy to get mineral ingredients like titanium dioxide into particles that are small enough to spread across your skin and still protect you. TikTok may try to convince you that you can make your own sunscreen out of diaper cream and coconut oil, but that’s just not how things work.
Myth: mineral sunscreen is better for the environment
Corals can (probably) be damaged by some types of sunscreens under the right conditions, but there isn’t a clear dividing line that casts mineral sunscreens as good and chemical ones as bad.
Oxybenzone, one of the chemicals that was found to damage corals in lab tests, has been banned in Hawaii. Some other sunscreen ingredients have also been found to cause damage. But that doesn’t mean mineral sunscreens are automatically safer. Research also shows that zinc oxide sunscreens are bad for corals. Meanwhile, it’s unclear whether sunscreen is actually reaching corals in amounts that are significant enough to affect them. “It is not clear whether [mineral sunscreens] are actually safer for corals,” says a Stanford article on sunscreen research.
The jury is still out on whether there’s a sunscreen choice that can benefit corals, but in her roundup of the research, chemist Michelle Wong has a list of sunscreen ingredients that are thought to be less harmful to corals. These include titanium dioxide—a popular ingredient in mineral sunscreens—and several chemical sunscreen ingredients, including octocrylene, octisalate, and avobenzone.
When you might want to use mineral sunscreens anyway
If you used to think that mineral sunscreens are always better than chemical ones, I hope I’ve helped you see the nuance behind the myths. But that doesn’t mean that mineral sunscreens are bad or useless.
One advantage to mineral sunscreens is that they’re less likely to trigger allergies or irritation, if you have sensitive skin. I use a mineral sunscreen stick on my face, even when I’m using chemical sunscreen on my body, because I’ve found that this mineral sunscreen won’t irritate my eyes if I accidentally get some in my eyes.
The American Academy of Dermatology recommends mineral sunscreens for people with sensitive skin and for babies. Otherwise they don’t prefer one formulation over another: “Any of these sunscreens can effectively protect you from the sun if you select one that is broad spectrum, water resistant, and has an SPF 30 or higher.”
Despite the misconception that mineral sunscreens reflect UV rays while chemical sunscreens absorb them, both types primarily absorb ultraviolet light. Contrary to popular belief, the FDA has banned the use of the term "sunblock" on sunscreen labels and advertisements, as no substance can truly block the sun.
