ecamsule (Mexoryl SX), and Tinosorb (which may be listed as methylene bis-benzotriazolyl tetramethylbutylphenol). [9,47]
You must apply sunscreen liberally to obtain the benefit of the SPF number on the label. Unfortunately, most people don’t apply sunscreen liberally and that is detrimental for their skin. This common mistake might lead you to believe that the sunscreen you applied isn’t effective. [9,47]
What about the recommendation you often see about reapplying sunscreen every two hours even if you’re not swimming or sweating? That’s a great question, with a somewhat complicated answer—but hang in there and we know you’ll get it.
Does the sunscreen you apply in the morning still work in the late afternoon, following a day at the office or at school? The answer is yes, depending on how much time you spend outdoors because the sunscreen actives break down in response to direct exposure to daylight, not in response to the passage of time during a single day. [9,47]
On an average day (if you’re in an office or otherwise indoors), your morning application of sunscreen is still going to provide sufficient UV protection on your way home, assuming you applied a liberal amount of an SPF 30 (or greater) in the morning.
If you spend the majority of your day outdoors, then the recommendation is to reapply every two hours, especially if you’re perspiring or swimming. This recommendation to reapply every two hours is based on the following.
Most people don’t apply sunscreen liberally, and if you don’t you won’t get the SPF protection rating shown on the label. If you’re one of those people who does not apply sunscreen liberally, then the apply-every-two-hours guideline makes sense, however impractical it may seem. The thinking goes like this: If you aren’t good about applying sunscreen liberally, then reapplying every two hours after direct daylight exposure will add up to liberal application because of the extra layers of sunscreen you’re putting on. [8,9]
How much to apply: There are many measurements given to help you figure out how much sunscreen to use, but in reality how much to use depends completely on the size of the area you’re covering. What we like to suggest is to smooth a layer of sunscreen over the skin that will be exposed to the sun so you can see it and then gently smooth it into skin and let it absorb. And, yes, we understand that it may feel a bit unpleasant until it is absorbed, but the protection it affords is worth this temporary feeling. Don’t forget your chest, arms, and hands (or any other areas of exposed skin)!
How often to apply: We know this one is repetitious, but we’re on a mission to ensure the best skin of your life starts now, and this is the first rule to make sure that happens. Aside from everyday use (no exceptions), a single application each morning with a product rated SPF 30 or greater will keep you protected for a normal workday (indoors), a walk to lunch, and the drive home. If you spend more than three or four hours in direct sunlight during the day, it’s a good idea to reapply your sunscreen—and, yes, that means redoing your makeup, which is why we advise touching up with a pressed powder rated SPF 15 or greater.
If you sweat profusely (think outdoor exercise or what can happen on a really humid day) or if you wash or sanitize your hands, swim, or get wet, you must reapply your sunscreen regardless of the SPF number on the product. If the sunscreen is labeled “very water resistant,” you get about 80 minutes of protection while perspiring or swimming. If the label states “water-resistant,” you get only about 40 minutes of protection if you get wet. [48] But don’t forget, even if you use those types of sunscreens, you’ll be rubbing them off when toweling dry, so in that scenario, be sure to reapply.
As you’ve seen, the rules for applying and reapplying sunscreen if you’re getting wet or sweating are entirely different from the rules if you stay dry and spend only limited time outside.
It’s also critical to understand that being inside doesn’t mean your skin is protected from sun exposure. If you’re sitting next to a window, it’s highly unlikely you’ll get sunburned because almost all windows protect you from UVB rays, the rays that cause burning. However, unless the window has special UVA shielding, your skin will NOT be protected from the sun’s UVA rays because these rays penetrate windows. [49] This is one of the factors you must take into consideration when deciding how often to reapply your sunscreen, or be sure you’re wearing sunscreens with higher SPF. You can also consider the following:
Find out if the windows filter both UVB and UVA rays.
Use blinds to control the amount of daylight that enters your work space.
Add a UV-filtering film to your office window; these films are sold in most major hardware stores and are easy to apply.
Common Sunscreen Questions, Answered!
What does “liberal” application really mean? As we mentioned above, there are varying measurements given to help you figure out how much sunscreen to apply. The standard often cited by dermatologists is to use an ounce of sunscreen (what would fill a standard shot glass) for head-to-toe coverage.[8,50] But, although well-meaning, this is just an impractical and somewhat illogical guideline.
The shot glass rule would apply only if you’re a thin, petite person wearing minimal clothing, such as a bathing suit for the beach or a tank top and shorts. If you’re a tall, heavyset person wearing minimal clothing, a shot glass amount literally won’t cover it. The total surface area exposed is what matters and a shot glass may or may not be enough. Following our rule of applying a layer of sunscreen you can see and then smoothing it over skin to let it absorb should work well.
Keep in mind that the more skin that’s covered by opaque clothing with a tight weave that doesn’t let sunlight through, the less sunscreen you need to apply because the clothing also provides protection. Don’t count on your clothing alone, however, especially for long days outside; for that, look to special sunscreen clothing companies, such as the Sun Precautions and Coolibar brands, which sell their products online and in some sporting goods stores.
Another option we recommend for achieving liberal application on your face is to layer sunscreens. For example, apply an amount of your daytime moisturizer with SPF 30 or greater that feels comfortable, and then follow it with a foundation rated SPF 15 or greater and set that with a pressed powder that provides additional sun protection. Voilà, you get great sun protection without skin feeling too slick or heavy from a liberal application of sunscreen.
Keep in mind that layering sunscreens is not additive; for example, applying an SPF 15 and an SPF 30 doesn’t net an SPF 45. However, adding sunscreen ingredients by layering different SPF-rated products absolutely helps boost protection, just how much more isn’t exact. Applying more sunscreen ingredients to your skin is how chemists formulate sunscreens to achieve higher SPF ratings—they add more active sunscreen ingredients! Now that’s sun-smart behavior!
When should you apply sunscreen? Every day, as the last step in your skincare routine. The vast majority of medical experts and skin researchers agree: Sunscreen is always, always, the final step in your skincare routine. [47,51] Any skincare product applied over a sunscreen dilutes the sunscreen, reducing its effectiveness to some degree. So, if you apply a moisturizer or a serum over your sunscreen, the amount of protection you get is reduced, and that’s a serious problem.
With the exception of a small minority of naysayers, the above guidelines are universally agreed on as the correct way to use sunscreens. Forgoing this important step is a disservice to the health and appearance of your skin, but, of course, this is your decision to make.
Do you need moisturizer AND sunscreen during the day? Typically, no. That’s because most sunscreens are formulated in a moisturizing base. Plus, the best ones
