Physical vs. Chemical Sunscreen: How to Choose - The Skincare Edit

Physical vs. Chemical Sunscreen: How to Tell the Difference and Which Type to Choose

Spoiler: Mineral protection is best.
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Given the choice, I will ALWAYS choose natural ingredients instead of chemical ones—and sunscreens are no exception.

You may have heard terms like physical, mineral, natural, chemical, organic and inorganic to describe sunscreen formulas...

But what does that even mean? And how do you choose the safest and best protection?

Help is here! In this article, you will find out:

  • The difference between the two types of sunscreen formulations
  • How each one works
  • The safety concerns you should know about
  • My favourite SPF formulas

What is a Physical Sunscreen?

CyberDerm Simply Zinc Ultra SPF 50

CyberDerm Simply Zinc Ultra SPF 50 is an example of a physical sunscreen.

Physical sunscreens are also known as mineral, natural or inorganic sunscreens. 

They're all the same thing—all of these terms refer to sunscreens that contain one or both of these mineral filters: 

  • zinc oxide
  • titanium dioxide

These ingredients protect you from the sun by acting like a physical block. They sit on top of your skin, and work by reflecting away the sunlight.

What is a Chemical Sunscreen?

Lancome Bienfait UV SPF 50 Super Fluid Facial Sunscreen

Lancôme Bienfait UV SPF 50+ Super Fluid Facial Sunscreen is an example of a chemical sunscreen.

Chemical sunscreens are also known as organic sunscreens—which is confusing, because that usually means "natural," whereas these ingredients are anything but!

Some of the most common chemical sunscreen filters include:

  • oxybenzone
  • avobenzone 
  • octisalate
  • octocrylene
  • homosalate 
  • octinoxate

Usually, these are found in combination rather than as a single active ingredient in a formula.

However, the easiest way to know whether or not an SPF is chemical is to look for zinc oxide and/or titanium dioxide. If they're not on the ingredients list, then you know it's a chemical formula!

Physical vs. Chemical Sunscreen Differences

Physical sunscreens remain on the skin's surface.

Here are the key differences between the two types of sunscreens—and why you might want to make the switch from chemical to physical!

1. Chemical Sunscreen Absorbs Into Your Bloodstream

DeVita Solar Protective Moisturizer SPF 30

DeVita Solar Protective Moisturizer SPF 30+ won't absorb into the bloodstream.

Mineral sunscreen is the safest, because it remains on the skin surface, your skin, and works by reflecting away the sunlight.

Chemical sunscreen, on the other hand, actually penetrates* right into your bloodstream. It works by absorbing the UV rays and converting them into heat that is released through the skin. But did you know that chemical ingredients such as oxybenzone can linger in our bodies for five days after a single application? It has been detected in breast milk, blood and urine. This study found it in the urine of 96 percent of 6 to 8 year old girls. 

I don't know about you, but if I have the choice, I'd much rather avoid products that enter and stay in my body. Plus, these researchers discovered something else: chemical sunscreen ingredients can act as penetration enhancers, helping any other chemicals you use to enter the skin.

* An exception is encapsulated octinoxate (found in CyberDerm Every Morning Sun Whip SPF 25). Encapsulation makes it act like the large molecules of mineral filters, which remain on the outer layer of dead skin instead of absorbing into the body. Because this technology is more expensive, you won't find it in mass-market sunscreens.

2. Chemical Sunscreen is Linked to Hormone Disruption

Juice Beauty SPF 30 Oil-Free Moisturizer

Juice Beauty SPF 30 Oil-Free Moisturizer contains zinc oxide, which is not linked to hormone disruption.

One of the biggest concerns with chemical sunscreen is that it might mimic, block or alter hormone levels—also known as endocrine disruption. 

Although there are no definitive answers YET, these researchers found that oxybenzone, homosalate and octinoxate affected thyroid and reproductive hormones in multiple animal and cell studies. This year, an Endocrine Society study reported evidence that eight chemical sunscreen ingredients interfere with human sperm cell function. So it's not a stretch to conclude that chemical SPF could be affecting our fertility.

There is no evidence for any hormone-disrupting effects from using zinc oxide or titanium dioxide. 

3. Chemical Sunscreen Can Cause Cell Damage

Aveeno Baby Sensitive Skin Sunscreen SPF 50

Aveeno Baby Sensitive Skin Sunscreen SPF 50 is a broad-spectrum, photostable physical sunscreen.

Another problem with chemical sunscreen is that it's linked to oxidative damage, thanks to inadequate protection from UVA rays. 

No doubt you've heard the words "free radicals" before, and know they're enemy number one in terms of skin aging. But what does that term really mean? It refers to highly reactive oxygen molecules—chemical byproducts that are generated from exposure to environmental factors such as smoking, pollution, and (you guessed it!) UV radiation. Free radicals encourage premature aging by attacking cell structures and degrading collagen and elastin fibres.

Because some sunscreen chemicals are not very photostable, they can amplify free radical production, releasing these harmful byproducts when they absorb UVA energy. In fact, this study found that some chemical filters may cause more free radicals to form than no sunscreen at all!

What's even more disturbing is that chemical sunscreen could cause gene mutations. Several studies (see here, here, here and here) have found that certain SPF ingredients generate DNA damage in human skin cells upon UV exposure. That means potential carcinogenicity. SCARY.

To suppress this cascade of free radical formation, you need a sunscreen with strong UVA filters. Zinc oxide is the best option because it offers broad-spectrum protection against both UVA and UVB rays. (Don't rely on titanium dioxide, as it's inadequate on its own for UVA protection.) 

The FDA's sunscreen monograph shows how the available ingredients compare. Zinc oxide comes out on top!

Check out the table above, via the U.S. Environmental Protection Agency, to see how the ingredients compare. I wish Health Canada had such a user-friendly chart!

4. Chemical Sunscreen May Trigger Skin Reactions and Acne

Derma E Natural Mineral Sunscreen SPF 30

Derma E Natural Mineral Sunscreen SPF 30 is lightweight and non-greasy.

If you have sensitive skin or are prone to allergies, a physical sunscreen is definitely the way to go. (Although I always say that it's good to err on the side of gentleness with your skin, in general, no matter what your skin type.) 

Chemical sunscreens are much more likely to trigger contact dermatitis; the symptoms can include rashes, itchiness, blisters and swelling. Oxybenzone is the worst culprit, but avobenzone, octinoxate and octocrylene are known to cause allergic skin reactions, too. 

There are no cases of skin allergy from zinc oxide or titanium dioxide.

If you're acne-prone, mineral filters are also best, because they're less comedogenic (pore-clogging) than chemical ingredients. Zinc oxide and titanium dioxide can even be slightly drying on the skin, making them ideal for normal to oily types—or anyone who wants to avoid a greasy feel. (Note: You'll of course want to check the other ingredients in any mineral formula for comedogenicity.)

5. Chemical Sunscreen Doesn't Protect You Right Away, and Needs Frequent Re-Application

Kosmea Moisturising Lotion SPF 30

With 20 percent zinc oxide, Kosmea Moisturising Lotion SPF 30 will start protecting you right away.

Remember how I said that physical sunscreen sits on top of your skin, whereas chemical sunscreen must be absorbed? Well, that means the minerals will start protecting you from the sun immediately, as soon as you apply them. With chemical SPF, you need to wait about 20 minutes before you're considered protected.

Many chemical sunscreens are also unstable, so they don't work for very long. They start to break down quickly in the sun, losing their effectiveness—which is why dermatologists are so adamant that we re-apply them often. Even though there are options that won't mess up your makeup, let's face it: re-application is kind of a pain!

In contrast, physical sunscreen lasts longer, provided you're not getting wet or excessively sweaty (which might make it wear off). Every two hours is the "golden rule" for sunscreen re-application, but if you did a thorough application of physical sunscreen in the morning and then spent most of the day indoors, then you're probably still adequately protected (as Dr. Cynthia Bailey suggests here). However, to be on the safe side, I would still re-apply physical SPF when outdoors for long periods of time.

6. Physical Sunscreen Can Feel Heavier and May Leave a White Cast

Drunk Elephant Umbra Tinte Physical Daily Defense Broad Spectrum Sunscreen SPF 30

Drunk Elephant Umbra Tinte Physical Daily Defense PF 30 is a tinted physical sunscreen that won't leave a white cast.

Now, here are the potential downsides of physical sunscreens. By nature, the active ingredients zinc oxide and titanium dioxide are heavier and can feel thick and a little bit greasy on the skin. Chemical filters, in contrast, often have a texture that is indistinguishable from a light moisturizer. 

The thing people complain about most is the white cast that zinc-based sunscreens can leave on the skin (unlike chemical formulas, which disappear). If you have time to wait, this does tend to disappear after a while as the sunscreen sinks into your skin. I would try waiting at least 15 minutes.

Alternatively, there are tinted formulas such as Drunk Elephant Umbra Tinte Physical Daily Defense SPF 30, which doesn't go on white at all. More options here

Related: Editor's Picks: 16 of the Best Tinted Mineral Sunscreens for Your Face

You also might be able to replicate the same effect by mixing some foundation or tinted moisturizer into your SPF. (Just don't dilute it too much, or you'll diminish the protection level!)

Even with these aesthetic issues, I still believe that physical filters are a better choice than chemical, which have much more serious risks!

Also, physical formulas do keep getting better and better—more lightweight and less whitening. This is because of nanoparticles (tiny particles of zinc oxide between one and 100 nanometres), which allow the formula to be more transparent. According to the Environmental Working Group, nanoparticles in sunscreen do not penetrate the skin or cause damage. 

Physical Sunscreen Recommendations

Physical sunscreen options from Badger, CyberDerm and Aveeno.

Here are a few of the physical sunscreens in my rotation. Keep in mind that the higher the zinc oxide concentration, the better! For more on how to choose a great sunscreen, see here.

  • Badger All Season Face Stick SPF 35: You have to rub this in to get rid of the white layer (and it's probably not great for darker skin tones), but I love the short organic ingredients list, and high (22.5 percent) zinc oxide content.

For more product recommendations, see my face sunscreen and body sunscreen guides!

Conclusion

Are you on board the physical sunscreen train with me? I hope these points have at least given you some food for thought!

Obviously, some sunscreen is better than no sunscreen—if the alternative is a burn—and the best sunscreen is the one you will ACTUALLY wear. (Which is why I included both physical and chemical options here.)

But given the many safety concerns I outlined, I do think it's well worth taking the time to find a physical formulation that works for your lifestyle, skin and budget. I'd love to hear about which ones are working (and not working) for you!

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Do you use physical or chemical sunscreen?
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