By now, you know the skin-health drill: Wear sunscreen. Reapply it. Daily. No exceptions. But do you know the differences between the oft-used terms physical and chemical when it comes to the non-negotiable product? The experts break it down.
They each protect differently:
The American Academy for Dermatology (AAD) summarizes this one succinctly in an easy-to-understand sentence: “A physical sunscreen protects by deflecting the sun’s rays, while a chemical one absorbs the sun’s rays.” Omaha, NE dermatologist and CEO of LovelySkin.com Joel Schlessinger, MD, also stresses the simplicity angle: “There are differences between chemical and physical sunscreens and while it may seem confusing, it really isn’t,” he says. “Basically, chemical sunscreens contain chemicals, which provide a different layer of protection, whereas physical sunscreens are probably safer in some respects, but don’t provide as much protection as chemical sunscreens.”
They each have different ingredients:
Physical sunscreens typically contain zinc oxide and mineral oxide, says Montclair, NJ dermatologist Jeanine Downie, MD. “These are physical blockers from the sun that reflect the sun’s rays,” she explains, adding that they tend to be whitish and can be difficult to rub into darker skin tones. “Chemical sunscreens also protect against UVA and UVB and can protect against infrared and HEV light as well.”
Likewise, Omaha, NE dermatologist Daniel Schlessinger, MD explains, you can look at physical sunscreens as having ingredients that do not absorb, but rather are designed to sit on top of the skin, “where they create a ‘shield’ that physically blocks and deflects the sun from the skin’s surface. Unlike their chemical counterparts, physical sunscreens start working immediately after application and are often thicker in consistency.”
For chemical sunscreens, Dr. Joel Schlessinger says that you’ll see common active ingredients like homosalate, oxybenzone, octinoxate, avobenzone and octocrylene among others on the ingredients list. “These are chemicals that operate like a sponge—they permeate the skin upon application and absorb UV rays where they then convert the rays to heat and release them from the body. This entire process helps prevent the UV rays from causing sun damage or sunburns in the skin. Sunscreen manufacturers may recommend that chemical sunscreens need time to fully take effect, but that isn’t how most people use them. I would prefer a sunscreen at any time even if it isn’t given the full 30 minutes post-application before sun exposure.”
But some cross over…
Not to get overly complicated with formulation facts, but the AAD does point out that the distinction between the duo isn’t always so black and white when it comes to ingredients: “Some sunscreens use both types of active ingredients, so they contain one or more active ingredient found in physical sunscreen and chemical sunscreen,” the Academy notes and offers this tip for how to tell: “You’ll find the list of active ingredients that a sunscreen contains on the container under the heading ‘active ingredients.’ If you are concerned about certain sunscreen ingredients, look for a sunscreen that contains different active ingredients.”
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They offer different advantages:
According to Dr. Downie—who stresses that everyone should use an SPF 30 every single day rain or shine regardless of your ethnicity, and it must be reapplied every two hours—chemical SPF varieties are “really good for if you need something that is more water-resistant or if you are going swimming. They tend to rub better into brown and black complexion.” On the other hand, when it comes to physical sunscreens, she lists that “advantages include that they tend to be less irritating and more hypoallergenic, but they can be thicker and might feel heavier on the skin.”
“I always tell my patients and our LovelySkin customers that the best sunscreen is always going to be the one that people will want to use, rather than the one that is super powerful, but isn’t likely to be put in your beach or tennis bag,” Dr. Joel Schlessinger says, although he does stress that if your plans involve a beach vacation, he does have a specific recommendation: “If you are planning a beach vacation or are someone who frequently swims in the ocean, I always advocate for a coral reef-safe physical sunscreen, preferably with non-nano zinc oxide. Researchers are now learning that the size of minerals may also be a detriment to our ocean’s coral reefs in addition to certain chemical sunscreen active ingredients. In fact, there are certain areas of the world that ban chemical sunscreens all together due to concerns about how it effects coral reefs, including Key West, Florida or Hawaii. Anywhere that there is a risk to the coral reefs will necessitate a physical sunscreen so, be sure to pack them in your travel bags.”
“Generally, your sunscreen choice largely hinges on personal preferences, but there are a couple factors in play when determining which might be best for you,” Dr. Daniel Schlessinger adds. “For example, I always recommend physical sunscreens for pregnant women, children and infants. Additionally, physical sunscreens are generally less likely to cause allergic reactions or skin irritation.”
If you are looking for the most lightweight formula that blends into skin the easiest and layers well with makeup, Dr. Daniel Schlessinger says that chemical sunscreens may be your best bet. “However, many of the newer mineral formulas are more elegant now than they previously were and blend into skin with less of a white cast. Most of my patients find that their preferred sunscreen option is often a hybrid of mineral and physical formulas. These can offer the best of both worlds by both deflecting and absorbing the sun’s UV rays, for better protection against the sun.”
And different aesthetic treatments call for different options:
As Lydia Sarfati, CEO and founder of Repêchage explains, when it comes to post-facial or post any invasive procedure—laser hair removal, microneedling, dermaplaning and waxing—you need to protect skin from UV light and environmental aggressors like free radicals and pollution with mineral-based, physical sunscreens, such as zinc oxide and titanium dioxide. “These ingredients work by creating a full-spectrum, physical barrier to protect the skin,” she says. “This type of protection is crucial after professional treatments. A long-lasting physical barrier in a waterless formula that combines mineral zinc oxide with ingredients that are high in natural antioxidants such as seaweed is ideal post-facials. I recommend non-migrating formulas that will not seep into the eyes causing redness and irritation; I also recommend mineral-based foundation to be applied after facial treatments, to help boost the physical protective layer.”
In both cases, number doesn’t necessarily matter:
While the AAD does recommend using a sunscreen with an SPF of at least 30, Sarfati warns that, after that, a higher SPF doesn’t tell the whole story. “Many people assume that a chemical sunscreen provides better sun protection because it may have a very high SPF. There are many factors involved when choosing a correct sunscreen. Full spectrum protection, which includes UVA and UVB light is crucial to prevent damage that can lead to skin cancer and skin aging. Physical sunscreens are naturally full-spectrum, while chemical sunscreens may not block UVA and UVB equally. The important point to know is that the higher numbers of SPF doesn’t give you more protection; they give you more extended protection. SPF, which stands for Sun Protection Factor, indicates how long you can stay exposed to the sun before you have to reapply your sunscreen.”
However, some other terms do:
You might know that SPF stands for Sun Protection Factor, but Dr. Carl Thornfeldt, dermatologist and founder skin-care line Epionce, explains why that’s so important to understand when choosing a sunscreen: “The SPF number refers to the amount of UVB protection it provides—how long the sun’s UVB rays would take to redden your skin. So if you use an SPF 30 properly, it would take you 30 times longer to burn than if you used no sunscreen.
He also stresses that it’s important to look for the words “broad spectrum” on a product’s label, which means it has ingredients that can protect you from UVA as well as UVB rays. “UVB rays cause sunburn and play a role in developing skin cancer. UVA rays cause skin damage that leads to sunburn and tanning, as well as skin aging.”
What’s more, Dr. Thornfeldt says, “waterproof” is not a proper term for describing sunscreens either. “’Water Resistant 80 minutes’ is the proper term approved for use by the FDA. This means the sunscreen maintained protection while being submerged in a water whirlpool for 80 minutes.”
And you might need more than just sunscreen:
Beyond slathering on the SPF, Dr. Joel Schlessinger says he always encourages his patients to have different layers of protection, whether it’s a piece of clothing, a hat or standing in a shaded area when possible. “Wearing UPF clothing to create an additional physical defense, seeking shade and wearing a wide-brimmed hat whenever you can is a valuable addition to any and all sunscreens.”
Another line of defense he likes: a supplement. “For my patients who plan on spending lots of time in the sun for a vacation or otherwise, or who have a higher risk of skin cancer, I highly recommend supplementing their sunscreen regimen with a dietary supplement called HELIOCARE Ultra Antioxidant Supplements ($62). They are dietary pills formulated with a special Central American fern and other chosen antioxidants that help boost the body’s tolerance to UV rays, working with your sunscreen to prevent damage. Interestingly, this is something that was first discovered when the Spanish conquistadors came to Central America and saw Native Americans were using the ferns to protect their skin. Subsequently, it has been perfected and turned into an oral supplement that is for the most part, grown and manufactured in Spain and then distributed across the world.”
The bottom line:
Chemical sunscreens:
Allow UV light into the skin. “Once the light is absorbed, the chemicals in the sunscreen create a chemical reaction in which UV light is converted to heat, and the heat dissipates,” Sarfati says. “This can create even more sensitization on skin that has been aggressed by treatments such as dermaplaning or extensive extractions.”
Physical sunscreens:
Create a physical barrier on the surface layer of the skin, preventing UV light and pollution from affecting the upper skin layers. “This effectively creates a protective shield from causing any sensitization from the UV light,” explains Sarfati. “The cons of zinc and titanium dioxide have been that, in the past, they created an opaque, white cast to the skin. This has now been greatly reduced with micronized formulas.
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