If you have ever survived an Arizona summer, you can certainly understand how unrelenting the sun can be. If you are reading this, hopefully you are already diligent about your use of sunscreen, however, in the event that you aren’t, here is your friendly reminder! When it comes to sunscreen, I have one hard and fast rule, use SOMETHING! I often get asked, what’s the best sunscreen? Well, that depends on a lot….and while sunscreen can be downright confusing with terms such as "all natural," "organic," "broad-spectrum," "water-resistant," or "non-nano" just to name a few, I try to make the world of sunscreens not so nebulous to patients. So then, what’s my answer to the question about the "best" sunscreen? Actually, it’s really very simple…ready?...the best sunscreen is simply the one you will wear…period! That means no matter the brand, the formula, the ingredients, the cost, the smell, or even that fancy retail packaging, ANY use of sunscreen is better than nothing. So now that you are doing the most important step of actually slathering on some form of UV-blocking goodness, let me provide you with some hopefully useful, research-based tips and tricks to get the most out of your sunscreen.
Newsflash!!! Most people don’t apply enough sunscreen! Across multiple studies people only apply ¼ to ½ the amount needed for the protection on the sunscreen’s label.2 Have you ever wondered why the FDA and other organizations keep the amount needed for SPF testing so high? Probably not, but as a skin nerd, I do! As it turns out 2.0 mg/cm2 is a bit of a sweet spot when it comes to reproducibility and reliability of the results.3 One of the easiest ways to help get you to actually achieving the amount needed on the skin is to apply your sunscreen twice. Apply a layer, let it dry, then apply a second layer. This particular method is recommended by the Japanese Ministry of the Environment.4 Furthermore, this will allow the sunscreen to absorb into the skin and be able to maximally exert is skin-protective effects. Also, when applying the sunscreen to your skin, try not to rub too much. One study found that vigorous rubbing actually reduced the SPF by 25%. Remember, you’re not trying to buff the paint off of your car, you are just trying to apply it evenly to surface of the skin so that it absorbs. Now that you are slathered up head to toe, you should wait at least 10-15 minutes before putting on or taking off clothes. Given everyone’s busy lifestyle, I realize this can be challenging (even for me), but this ensures that the sunscreen will dry completely and to prevent the clothing from wiping it off the skin.6 The World Health Organization (a bunch of really smart people) recommends reapplying your sunscreen every two hours. Yes, every 2 hours! Realistically most of us won’t do that, but you should aim to reapply your sunscreen at least once, and especially after physical activity or swimming and bathing.7 If you don’t feel like reapplying, do yourself a favor by wearing sun protective clothing paired with a wide-brimmed hat. Nowadays so many companies are making fashionable clothing with built in UPF (sun protective rating for clothing), you really have no excuses not to be properly protected from the sun. They even have some pretty sweet sun protective umbrellas on the market! My personal favorite is from Coolibar.
But back to business though. When you reapply your sunscreen, even just once, you can reduce your risk of sunburn by 2 to 3 fold! While there is a bit of debate on when to reapply, aim to do it at least once throughout the day.8 One study found that only 60% of the applied sunscreen was still on the skin after 4 hours of wearing clothes, physical activity, and bathing, and only 40% after 8 hours.9 If you’re lucky enough to live near a beach, be aware that sand can wreak havoc on your sunscreen. One study noted up to 59% could be potentially removed by laying on the sand.10 For the rest of us getting ready for a big day of fun in the sun, make sure to apply your sunscreen BEFORE stepping out in the sun! One study of people on vacation found that they were, on average, getting 100 minutes of UV exposure before they applied their sunscreen! That was almost 30% of the amount needed for a sunburn in some cases.11 Now while there isn’t a big difference in amount of UV filtered out by an SPF 30 and an SPF 50 sunscreen, it can certainly help make up for us not applying enough (which we are actually guilty of). Ready for a pretty interesting fact? One experiment found that an SPF 100 sunscreen applied normally (which is to say, not enough) offered an SPF of 27!12
Interestingly, non-organic and organic (or physical / chemical if you prefer) sunscreens, don’t actually protect our skin by reflecting and scattering UV energy. How sunscreens do work is by attenuating the UV energy, absorbing it and turning it into less harmful energy - most often in the form of heat. Titanium dioxide and zinc oxide do reflect some of the UVA wavelengths, but they reflect much more in visible light spectrum, which is why they can leave their characteristic white-cast on the skin, but micronization can help reduce this effect!13
You deserve to enjoy your time outside in the sun, but you can be sun-smart when doing so. Not only does reducing UV exposure slow down extrinsic aging, hyperpigmentation of the skin, and the formation of broken capillaries, but it also reduces your risk of certain types of skin cancers and helps prevent the immune suppression caused by UV – so it’s really win-win!
-The Skin Doc.