Your SPF Questions, Answered


This story ran as a part of Sun Week on ITG, a celebration dedicated to the one part of your beauty routine you can't opt out of: sun protection. (Lipstick is fun and all, but never life or death). We also launched Glossier's very own version. Explore more Sun Week content here. The future's so bright, gotta wear sunscreen.

You asked, they answered. We took your 300-some comments on Tuesday's Open Thread, plucked the most-asked queries, and fired them off to our network of dermatologists, aestheticians, and skincare-inclined friends standing by. The result is a fairly comprehensive Sunscreen FAQ, and we're delighted to share. Let's get into it:

Q: So I know sunscreen is only good if you reapply... but how often and under what circumstances? I've heard every two hours, and always assumed that was two hours from when you applied it, even if you weren't outside that whole time. But then I heard somewhere else that it's only for every two hours of sun exposure because one of the ingredients is photosensitive and breaks down with sun exposure? I have no idea! Please advise.
A: Reapplication time actually has nothing to do with breakdown of ingredients in the sunscreen. Instead it has to do with the sunscreen just "washing off" whether from regular sweat, insensible sweat (see below) or swimming. Every time you come out of the water, and also every time you sweat, you should re-apply your sunscreen. And you may not know this, but even if you’re not doing any activities—if you’re just sitting under an umbrella at the pool or at the beach and you’re reading—you still need to re-apply every 2-3 hours. Why? Because you’re always perspiring even though you can’t feel it (what we call “insensible perspiration"—it evaporates as fast as you make it so it doesn’t accumulate on your skin and therefore you don’t feel it), so sunscreen is always being washed off your skin. Even if it's labeled water-resistant, always reapply. —Dr. Neal Schultz, NYC-based dermatologist, host of, and creator of BeautyRx by Dr. Schultz.

Q: Some facialists (featured here) suggest that daily sunscreen use can be bad since the product is sticky and pore-blocking, and so its use should be limited to anticipated sun exposure. Everyone, hopefully, goes outside every day. How much sun exposure warrants sunscreen?
A: The single most important thing you can do for your skin is to protect it from the sun. Sun exposure ages your skin and is extremely hard to reverse later in life. Stay out of the sun as much as possible and apply an SPF 30 daily. There are amazing oil-free sunscreens that provide the protection you need without clogging your pores. Shani Darden, licensed aesthetician

Q: How do I KNOW my skin is being protected from the sun?
A: Chances are, if your skin is flawless and you see no signs of photo aging, you've been really diligent about protecting your skin from the damaging rays of the sun. UVA is present 365 days a year and it is the UVA that gives us the predominant symptoms of photo damage that causes aging of the skin. If you have dull, lackluster skin with irregular pigmentation, melasma, brown spots (lentigines), broken capillaries, wrinkles and loss of elasticity, it's likely you've had more than a reasonable amount of unprotected sun exposure. It's cliché, but true—you'll know it when you see the results. Dr. Patricia Wexler, NYC-based dermatologist

Q: I have acne-prone skin and I worry about reapplying sunscreen to a face that isn't freshly washed. Aren't I just rubbing dust and dirt (that's invisibly stuck to my tinted moisturizer) into my skin? Bringing a makeup wipe and rubbing off my base and my blush and then reapplying everything just seems so not worth it. Maybe SPF in powder form, but that takes away the glow. Help?
A: Great question and one that I get asked a lot. It would, unfortunately, not be very practical to wash skin mid-day and start all over again with your makeup. The best solution (and something I personally love to do) would be to mix a powder with SPF along with a makeup powder that gives the skin a smooth, flawless glow. Colorescience SPF 50 Mineral Powder and Bare Minerals Illuminating Veil are my go-to’s for this. When mixed together, they provide the skin with a less powdery, more glowy look while still providing all of the benefits of SPF. You’ll want to make sure to apply it generously and every few hours. —Renée Rouleau, licensed aesthetician

Q: I think we have established that sunscreen = important and what the negative effects of the sun are, but can we get some advice about the positive effects of the sun? Like what is an appropriate amount of sun to get to reap benefits like vitamin D and to stave off SAD?

A: There are no positive effects of UV rays on the skin unless someone has psoriasis or another skin disease that improves with UV therapy. As for vitamin D, it should be eaten and taken as a supplement if one is deficient. SAD does not require UV rays, it requires broad spectrum light, or visible sunlight. The angle is low in the fall and winter here [in the United States] so the amount of light often isn’t enough, which is why broad spectrum light boxes are recommended to people with SAD. Dr. Amy Wechsler, NYC-based dermatologist

Q: What is your opinion on CC creams, BB creams, and foundations that have SPF? Are these actually able to provide enough sun protection? Also, I've heard that a sizable amount of sunscreen is needed in order to be most effective. Does this apply to face makeup with SPF?
A: Absolutely! CC/BB/tinted moisturizers can provide enough sun protection IF you put on enough. The general rule is 1/4 teaspoon or 2.0 mg/cm2 to get the right amount of protection for your face and neck. Buy a little measuring 1/4 tsp (you can find them at any baking or grocery store) and actually measure it out—it'll look like a nickel-sized dollop. You'll probably be surprised to see most of us aren't even close to using how much we should be. You can also try putting on half of what's in that 1/4 tsp, letting it dry, then putting on the second layer. Using your face makeup/foundation [with SPF] can be an option, but not really a realistic one. They tend to be way more pigmented then BB/CC/tinted moisturizers, so the coverage might be too heavy. Jordana Mattioli, licensed aesthetician, Complete Skin MD

Q: I have terrible melasma—severe dark patches that change place and move around, and my skin is plagued with ever-changing 'grubby' appearance. Do you know of any treatments for this that ACTUALLY WORK? And then which sunscreen is best after treatment to prevent reoccurrence? Thanks team!
A: Retinol and AHAs can help lighten pigmentation and melasma. As far as treatments, chemical peels and laser treatments can reduce the appearance of melasma; however, it’s prone to come back due to hormones, sun, or heat. I recommend using a zinc-based sunscreen after treatment to protect your skin from the sun and help prevent reoccurrence. —Shani Darden

Q: Are you guys able to explain PA++ ratings on Asian sunscreens? I've got the Wiki explanation but I want to know how to figure out the PA ratings of western sunscreens that just state spf.
A: I come to you not as an expert, but as somebody who is besotted with Japanese SPFs. PA is a Japanese rating, and it's a factor that explains the product's UVA protection. The United States equivalent is PPD, which stands for Persistent Pigment Darkening. Most full coverage sunscreens hover around 5-6, which translates to PA++. PPD is hard to find out for sure because a lot of companies in the US don't test for it, however you have to have adequate UVA protection to pass FDA standards, so you're likely covered with whatever you've got going on now. There's also this enormous and comprehensive Reddit spreadsheet that has a lot of PPD information. Go to it, bookmark it, never let it go. —Brennan Kilbane, ITG's associate editor

Q: I read that we're exposed to much more intense sunlight when we fly. Should I wear higher SPF or reapply sunscreen when I'm on a plane?
A: This is very true and yes, you should be applying SPF when flying. Did you know that when you're in an airplane, you’re closer to the sun so UV damage is at its greatest? Also, UV radiation can also increase when the plane flies over thick cloud cover or snow fields, which can reflect up to 85% of the UV radiation. The windows on an airplane don’t do an efficient job when filtering out damaging UV rays, so you most definitely are still exposed. Two suggestions: 1) When possible always book your seat next to the window so you can control the shade and in this case, keep the shade closed! 2) You don’t need to wear a higher SPF—a minimum of SPF 30 is adequate—but you do need to apply it generously since the protection a sunscreen gives depends on a nice, thick layer. —Renée Rouleau

Q: What do I use if I have acne-prone skin?! I feel like sunscreen just makes it worse but I don't want to ruin my youthful skin with the sun and have premature wrinkles!
A: I have the exact same issue, so I know first hand your struggle with finding the perfect SPF. My advice is to try an SPF with only zinc oxide and/or titanium dioxide as the active SPF ingredients—those are minerals that are referred to as physical blocks. They provide broad spectrum protection by deflecting and scattering rays, which keeps the skin a bit cooler—helpful for acne and sensitive skin. If you're using acne-fighting products regularly, then you want to be super gentle with your SPF, and mineral-based will be best. Think about how many layers you're putting on in the morning, too. When you're acne-prone, less is more. Try an SPF formula loaded with antioxidants in a texture that you like- this way your SPF can be an 'all in one' product. MD Solar Sciences, Paula's Choice, and Elta MD have some great physical-only SPF options for acne-prone skin. —Jordana Mattioli

Q: Is there anything I can do to reverse any damage I may have incurred from the sun?
A: The signs of sun damage are brown spots, fine lines, pigmentation changes, and skin cancer. Any mole which has grown, changes shape, has a poorly defined border, becomes ulcerated, or bleeds should be evaluated by a dermatologist and possibly biopsied. Fine lines can be improved with Botox and dermal fillers. Pigmentation changes can be lightened using lightening creams with kojic acid. A set of three medium strength peels helps to even out your skin tone and brighten your complexion. One of my favorites is the VI Peel. Laser treatments are also excellent for difficult dark spots. Dr. Melissa Doft, NYC-based plastic surgeon

Q: If you've been remiss about suncare, where do you start?
A: I recommend an SPF 30 from October through April and an SPF 46 from May through September. Always broad spectrum. SPF with antioxidants tend to be more stable. Obviously, seek shade—especially between the hours of 11AM and 4PM. Check with your doctor to see if you are on any photo toxic medications, making you more sensitive—like doxycycline, laxatives, diuretics, or chemotherapy. Also, try clothing with a label of UPF (Ultraviolet Protective Fabric)—if worn properly, you won't require additional SPF. Polarized glasses give necessary protection for the macula and retina. A baseball cap will give only overhead protection; instead, wear a hat with a wide brim. They can laugh at you now—you can laugh when THEY have the wrinkles! —Dr. Pat Wexler

Photo via ITG.

Sun Week is still underway. Read more here.