Your Top Sunscreen Questions, Answered

Everything a dermatologist wants you to know about picking the right SPF for you.

by Beth Shapouri Health Writer

This summer is going to look different from last year, mostly in a good way. We’re ready to spend a little extra time outside, with friends and family, and indulging in honest-to-goodness fun (remember that?). How do we do it safely? Your guide to a healthy, happy summer starts here.

There are so many sunscreens out there to choose from and finding that one ideal formula you know you can trust is intimidating. In fact, it’s hard to know what “ideal” even means. When it comes to preventing sun damage (and ultimately skin cancer), what really matters? What level of SPF is enough? What’s the difference between a chemical barrier and a physical barrier? Dendy Engelman, M.D., a board-certified cosmetic dermatologist, Moh's surgeon, and assistant clinical professor at Albert Einstein College of Medicine in New York City breaks down the answers to all your biggest questions about choosing your best sunscreen and how to use it to get the maximum benefit.

HealthCentral: What’s the difference between a chemical and physical sunscreen?

Dr. Engelman: Physical sunscreen (also known as mineral sunscreen because its active ingredients are minerals like zinc oxide and titanium dioxide) acts as a shield for your skin by sitting on the skin’s surface and deflecting harmful UV (ultraviolet) rays. Physical sunscreen is a great option if you need to quickly apply sunscreen and go, because it starts protecting you right away. It is also a safer option for children and pregnant women versus chemical sunscreen, which is absorbed into the bloodstream [according to a recent study published in JAMA] and can be less irritating to those with sensitive skin or skin conditions like rosacea. However, since physical sunscreen sits on top of your skin, you will need to reapply more frequently, especially if you are in the sun for long periods of time or participating in activities that may cause your sunblock to wear off, like swimming or sweating.

Chemical sunscreens contain UVB- and UVA-absorbing chemicals, which transform UV rays into heat through a chemical reaction, then release the heat. You need to apply chemical sunscreen at least half an hour before going out into the sun, as it takes some time to absorb and start protecting you. However, it is preferable if you are planning to be in the sun for a long period of time, as you will need to reapply less frequently.

And as long as you are applying enough sunscreen [a shot-glass for your body; a nickel-size for your face, according to the Skin Cancer Foundation] and re-applying as needed, both will provide sufficient protection against long- and short-term skin damage. I actually recommend that patients use both chemical and physical sunscreen (apply chemical first, then apply a layer of physical sunscreen) for additional protection.

HC: How do sunscreens with all-natural ingredients measure up to the others?

Dr. Engelman: While “natural” can be a misleading term—as it can refer to ingredients that are irritating to skin, even though they may be found in nature—some natural sunscreens are amazing. What we really mean is mineral-based, physical blockers like the zinc oxide and titanium dioxide I mentioned, which we know to be effective. As a bonus, all-natural formulas have (been) found to be more reef-friendly [according to the National Parks Service]. I like Blue Lizard Australian Sensitive Mineral Sunscreen SPF 50+ because it is great for all skin types, including sensitive skin and those with skin conditions like eczema and rosacea.

HC: Is there anything specific to look for—or avoid—when choosing a formula?

Dr. Engelman: I recommend looking for sunscreen formulas that are non-comedogenic and fragrance-free. Formulas with antioxidants like vitamin C and idebenone are great for combating free radical damage from UV rays and other environmental aggressors [which can cause aging]. I love Elizabeth Arden PREVAGE City Smart SPF 50, a tinted physical sunscreen.

One of my favorite skincare secrets is to apply a vitamin C serum before putting on sunscreen to help prevent acne breakouts and further fight free-radical damage Bliss Bright Idea Serum is a great option, as it contains tri-peptide to improve skin’s elasticity, in addition to providing antioxidant benefits with vitamin C. For those who like to incorporate a facial oil in their skincare, Melach 33’s Rimmon Elixir Face Oil is filler-free and packed with antioxidant-rich nourishing oils.

HC: What level of SPF do you really need?

Dr. Engelman: While the American Academy of Dermatology recommends an SPF 30 or above, I always recommend that patients use SPF 50 or above, as studies [including one published in the Journal of the American Academy of Dermatology] have shown that higher levels of SPF offer more protection than lower SPF. Even small amounts of sun exposure add up over time, so using a high-SPF sunscreen can prevent serious UV damage.

HC: Does it matter if you use a spray vs. a cream formula?

Dr. Engelman: If you are using a spray-on sunscreen, you need to apply a lot more product than you think to achieve full coverage. It is also difficult to tell how much of the formula is actually reaching your skin, and if there are any areas you’ve missed. That’s why I generally recommend using a cream formula first to ensure that you are sufficiently protecting all exposed skin. You can use a spray sunscreen to reapply, but you should still rub it in.

HC: Minerals can show up on dark skin—what’s your advice for picking a sunscreen for deep complexions?

Dr. Engelman: There are many great sunscreens on the market for those with darker skin tones. Chemical sunscreens do not leave behind residue on anyone. When it comes to finding a mineral-based formula that works on dark skin, it can be a bit of trial and error, but there are so many great ones now; it truly is possible to find them! Glo Skin Beauty’s Moisturizing Tint SPF 30+ provides oil-free sun protection and hydration, along with a beautiful wash of color. Supergoop Mineral Sheerscreen SPF 30 is sheer and suitable for all skin types, offering broad-spectrum and blue-light protection.

HC: Do you really have to reapply it every two hours?

Dr. Engelman: No one wants to hear this, but yes, reapplication is very important. Here is the advice I give my patients for maximum protection with minimum effort: I recommend starting with a chemical sunscreen about half an hour before going out in the sun. While you wait for it to activate, apply physical sunscreen to act as a shield and offer another layer of protection. When you need to reapply (about two hours after your first application, or every hour if you are participating in activities like swimming that cause your sunscreen to wear off) use a physical sunscreen in a cream or spray formula. Just be sure to rub it in!

Beth Shapouri
Meet Our Writer
Beth Shapouri

Beth Shapouri is an award-winning beauty, health, wellness, and lifestyle freelance writer whose work has appeared in Glamour.com, Elle.com, Health Monitor, Magnolia Journal, Marie Claire, RealSelf.com and more. Career highlights include a multi-year stint as Lead Beauty Writer for Glamour.com and contributing to a New York Magazine package on circumcision that received a National Magazine Award for service.