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Foggy glasses—caused by a mismatch between the temperature of your breath and the surrounding environment—can range from a mild annoyance to a vision-clouding hazard, and the problem is all the more common now with the daily wearing of face masks. Long used for occupational safety and recreational sports, anti-fog agents such as balms, drops, sprays, and wipes are meant to repel or evenly distribute fog, the fine droplets of water that accumulate on hard surfaces, so you can better see through your lenses. Trouble is, not all of them work that well, or for very long. We tested three anti-fog drops, two anti-fog sprays, and one reusable anti-fog wipe in various environments, and we found Ultra Clarity’s Defog It drops to be the most compatible with different lens types and coatings. However, they require frequent reapplication and can leave vision-blurring streaks—and as we found in our testing, your spit might work just as well.

The most effective way to reduce fogging on glasses or goggles while you’re wearing a face mask is to improve the seal between the top of the mask and your skin. Masks with adjustable nose-bridge wires are useful for this purpose, though even masks with the sturdiest wires can still let air escape at the top of the mask, which can fog up your lenses. Surgeons have long taped the tops of their masks to their faces to seal them off completely, preventing fogging. Surgical tape, also known as paper tape, or adhesive bandages can work well for this purpose.

If you’ve bought a well-fitting, wired face mask but still experience fogging, and if taping your mask to your face seems impractical, you may find the Defog It drops worth a try. Know, though, that while this formula was our testers’ favorite overall, individual results were mixed (and reflective of the many one- or five-star customer reviews for anti-fog sprays and drops).

Optometrist Dr. Andrew Williams of Vea Eye Health Professionals in Atlanta said that since the start of the pandemic he has fitted a number of patients, who are fed up with foggy glasses and poorly performing anti-fog agents, for contact lenses. Some plan to return to wearing glasses once face masks are no longer necessary. “I’ve had actually quite a few patients come in who’ve requested contacts to try to just wait it out,” Williams said.

These anti-fog drops are more expensive per milliliter than others we considered, but they performed adequately most often in our testing, with the fewest tester complaints of lens streaking. They’re currently available only in a kit that includes a microfiber cloth, which is great if you need one and less appealing if you don’t.

*At the time of publishing, the price was $16.

One tester, who used Defog It drops as they went about their day wearing glasses and a mask indoors and out during a period of mercurial weather shifts in Buffalo, New York, found that the drops lessened—though did not eliminate—glasses fogging. “But it left huge streaks on the lenses that I couldn’t buff out without removing the whole [application], and it makes light reflect weird on my lenses,” they said.

To learn all we could about commercial anti-fog agents, we spoke with Gaétan Laroche, a professor of materials engineering at Laval University who along with colleagues has developed patented permanent anti-fog coatings, primarily for use in health-care and research settings but also for eyeglasses; Michael Vitale, senior technical director at The Vision Council, a trade association representing the vision care industry; Dr. Andrew Williams, an optometrist at Vea Eye Health Professionals in Atlanta; and Scott Newman, president and CEO of Sven Can See, which manufactures an anti-fog/anti-frost lens treatment.

I’m the editor of health, fitness, and personal-care coverage at Wirecutter, where I edit guides on everything from shopping for a cloth face mask to choosing an online therapy platform. I’ve covered science and health for more than a decade. Like many people, I’ve experienced the frustration caused by fogged-up lenses.

People in several occupations have long dealt with lens fogging as a matter of course, but now that more people are wearing face masks to help prevent the spread of the coronavirus, everyday glasses-wearers are more often experiencing fogged-up lenses. A well-fitting mask, ideally with an adjustable nose-bridge wire, can help reduce the amount of exhaled breath that reaches your glasses, thereby reducing the potential for fogging. But that alone might not be enough to ensure you can see.

Many health-care professionals, machinists, skiers, lab researchers, and scuba divers have found commercial anti-fog agents useful for reducing the accumulation of vision-clouding water droplets on their glasses, goggles, or other protective eyewear.

Scott Newman, president and CEO of Sven Can See, which makes an anti-fog/anti-frost treatment, said his business saw a shift in its customer base shortly after the coronavirus pandemic began. Whereas before COVID-19 the company’s primary clients were winter athletes, now it is selling more often to first responders and medical professionals. With mask wearing being the new normal, “we went from your standard, seasonal-based product to a non-seasonal product,” he said. “Everybody uses this all the time.”

Most anti-fog sprays and gels are hydrophilic solutions that attract water molecules to your lenses such that they can disperse evenly, resulting in a continuous layer you can see through. Alternatively, surfactant films can reduce fogging by reducing the surface tension of water molecules that accumulate on your lenses.

“Fog is the formation of water droplets on top of a surface, which lead to the formation of visual artifacts,” said materials engineer Gaétan Laroche of Laval University. “To remove these visual artifacts, the idea is to make a continuous film of water on top of [the] glass. If you have this continuous film of water, the artifacts will somewhat disappear, and it will be possible to view through the glass surface without any deformation of the image.”

Coatings that are too hydrophilic, however, can also attract dirt. That’s why many eyeglass lenses are sold with some kind of permanent hydrophobic—water-repelling—coating applied.

According to the most recent data from eye-care industry trade association The Vision Council, roughly half (45.6%) of prescription lenses sold in the US between March 2019 and March 2020 had anti-reflective coatings applied. The vast majority of these lenses, 88.5%, also had a UV-protective coating. Over a third (36.9%) of prescription lenses sold in the US during the same time period were polarized.

“Generally, lenses that have hydrophobic and oleophobic anti-reflective coatings may not be very compatible with anti-fog sprays, wipes, balms, etc., since these anti-fog agents wipe off very easily and may also increase the reflectance,” Michael Vitale, senior technical director at The Vision Council, wrote in an email. “For general lenses that have scratch resistance coatings, however, including tinted, polarized, and UV protected lenses, anti-fog applications might perform fairly well.”

They do, however, require frequent reapplication. “It’s almost like waxing a car,” said optometrist Dr. Andrew Williams.

“Generally, lenses that have ... anti-reflective coatings may not be very compatible with anti-fog.” —Michael Vitale, The Vision Council

Ultimately, any one person’s results with a given anti-fog agent depends on the composition and coatings of their lenses, the evenness of the application, and the particulars of their environment. Although the drops we recommend performed adequately for most of our testers, they will not work well on all lenses and in all situations. So it’s best to try any balm, drops, or spray at home before trusting that it will suit your needs out in the world.

The experts we consulted recommended against using any anti-fog or lens-cleaning solutions that contain alcohols, which can damage certain finishes on some lenses. But the makers of anti-fog solutions aren’t required to disclose the ingredients in their formulas. If anything, some say only what their formulas don’t include (usually, lens-damaging alcohols).

We looked for anti-fog agents marketed specifically for use on eyeglasses and safety goggles (versus ski masks or swim goggles). We then combed through customer reviews of top-rated best sellers, looking for details on lens-coating compatibility and use in conjunction with face masks.

No one product scores well with all reviewers, even when you control for self-reported lens coatings. Some reviewers say a given spray, gel, balm, or wipe works well, while just as many complain about wasted money. It’s a real crapshoot.

Ultimately, we bet on six popular, (mostly) well-reviewed anti-fog products that were ready to ship during our test period:

In non-scientific trials using a pair of non-prescription glasses with polycarbonate lenses, we assessed how the various liquids (and the reusable wipe) distributed or repelled water droplets across treated versus untreated lenses subjected to rapid temperature changes: being transferred from a shelf in a refrigerator to the top of a steaming cup of coffee, or being moved from the author’s face—after spending five minutes outside in direct sun on a hot (90 °F), humid (86%) day—to a <0 °F freezer drawer. Between trials, we removed any residual anti-fog treatment using a soap-free commercial lens cleaner.

We eliminated the reusable wipe from consideration following these tests, as it performed poorly compared with the sprays and drops in every scenario. We also found that drops consistently made for an easier, more even application than sprays did.

We then asked four additional people in different geographic locations to try the most promising drops as they went about their daily lives, wearing glasses with their preferred face masks. They assessed both efficacy and longevity—how often they had to reapply a particular agent for optimal results.

Tester 1 (the author): Wore non-prescription glasses with polycarbonate lenses treated with anti-reflective, UV 400, and blue-light-blocking lens coatings in Atlanta.

Tester 2: Wore single-vision prescription glasses with an anti-reflective lens coating in New York City.

Tester 3: Wore single-vision prescription glasses with anti-reflective, UV 400, and anti-scratch lens coatings in Boulder, Colorado.

Tester 4: Wore single-vision prescription glasses with anti-reflective and UV 400 lens coatings in the San Francisco Bay Area.

Tester 5: Wore single-vision prescription glasses with anti-reflective and UV 400 lens coatings in Buffalo, New York.

We also tried coating test lenses in a household surfactant and spit.

These anti-fog drops are more expensive per milliliter than others we considered, but they performed adequately most often in our testing, with the fewest tester complaints of lens streaking. They’re currently available only in a kit that includes a microfiber cloth, which is great if you need one and less appealing if you don’t.

*At the time of publishing, the price was $16.

Though Ultra Clarity’s Defog It drops did not work consistently for all five of our testers, it is the commercial anti-fog agent we’d try first. At around 16¢ per application, which we found on average to last roughly an hour, it’s a costlier option compared with using a household surfactant or spit. However, it’s easier to apply than those DIY solutions, more frequently resulting in an even layer that better distributes water droplets across lenses with various coatings, including anti-reflective and UV-protective ones.

Defog It will not work on all lenses and in all environments. So if it doesn’t suit your needs, you’ll be out around $16 (or more, depending on shipping costs and potential price spikes). That could make a frustrating situation—fogged-up glasses—doubly frustrating.

A drop or two of Defog It per dry lens should suffice. Use a microfiber cloth to buff it in. To remove Defog It from your lenses, clean your glasses as you normally would, no special solution necessary.

Two of our five test panelists found that Defog It worked well for their purposes. A tester who used these drops while going about his day and out for runs in New York found that it worked wonderfully: “It’s like I’m not wearing a mask,” he said.

The other three panelists wouldn’t bother with Defog It or the other drops they tried. “It was kind of a pain to put on, and if I didn’t clean thoroughly between uses, it caused my glasses to be blurry,” a tester in Boulder, Colorado, reported.

Before shelling out for drops that may not work for you, consider trying baby shampoo, dish soap, or saliva (again, first at home).

In a pinch, any household surfactant or saliva may help reduce lens fogging. As with the anti-fog drops, you have to buff the substance into your lenses with a microfiber cloth in order to achieve as even an application as possible. And you should expect some streaking.

Human saliva is full of surfactant proteins. They’re the reason your spit sometimes sticks to the bowl of a porcelain sink and resists being rinsed down.

We tried coating our test lenses in baby shampoo (a favorite of some divers), fragrance-free dish soap, and spit, finding spit to be the most effective anti-fog agent of the three. In three out of three comparative trials, the author’s saliva matched the performance of the Ultra Clarity Defog It drops. Of course, as The New York Times notes, “given that we’re dealing with a respiratory virus and trying to stop the spread of germs, spitting on your glasses is not advised during a pandemic.”

If you’re sure you want to try a commercial anti-fog formula, and the Ultra Clarity Defog It Anti-Fog Kit is unavailable, consider Dynamic Labs’s Fog Stopper, which performed second-best in our chill-to-steam and face-to-freezer testing and was our test panelists’ second choice of the two drops they tried. Like Defog It, Fog Stopper will not work on every lens and in every environment. “I was positively surprised by the Fog Stopper at first: It initially appears to almost completely prevent fogging in the places it’s applied, and doesn’t leave streaks,” one tester said. “But then when I walked outside, it kind of hit a limit, and the whole lens fogged up like it was really wet. [It] wouldn’t decloud, and everything was blurry.”

Optix 55 Anti-Fog Treatment for Anti-Reflective Lenses performed poorly compared with both Defog It and Fog Stopper in our panel testing. Like all the anti-fog agents we considered for this review, these Optix 55 drops are either “miraculous” or “useless,” depending on who you ask.

Optix 55’s Fog Gone Anti-Fog Spray for non-anti-reflective lenses occasionally made lens fogging worse compared with an untreated lens in our tests, as did the Just Add Water Jaws Quick Spit Antifog spray and the LifeArt Anti-Fog Wipes.

Gaétan Laroche, professor of materials engineering at Laval University, phone interview, June 22, 2020

Scott Newman, president and CEO, Sven Can See, phone interview, June 9, 2020

Michael Vitale and Hayley Rakus, senior technical director and marketing and communications manager, The Vision Council, email interviews, June 17–18, 2020

Dr. Andrew Williams, optometrist, Vea Eye Health Professionals, phone interview, December 21, 2020

Tracy Vence is a supervising editor overseeing Wirecutter’s health, fitness, personal care, and adult coverage. Previously she was a news editor for science magazines.

by Joanne Chen and Alejandra Matos

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