Healthy Living

The ABCs of SPF: Making Sense of Sunscreen Labels

Jul. 7, 2015
Though some may find a suntan attractive, it’s actually a sign of damage to skin cells—the kind of damage that may lead to skin cancer. And while it’s the most common type of cancer, with proper sunscreen use, skin cancer is also the most preventable type of cancer.
UR Medicine dermatologist Dr. Sherrif Ibrahim offers some "ABCs" to help you learn what to look for when shopping for sunscreen and how to decipher some of the labeling language.
father applying sunscreen to his son
A: All-ray protection: Make sure your sunscreen is labeled as “broad spectrum.” That means it protects against both UV-A and UV-B rays, both of which can lead to skin cancer.
B: Be SPF wise: The sun protection factor, or SPF, should be at least 30 but doesn’t need to be higher than 50. According to the FDA’s new labeling, anything under SPF 15 does not adequately prevent skin cancer. The higher the SPF, the better; however, once you get up to 50 SPF, about 98 percent of UV rays are filtered out. New labeling will eliminate SPF values beyond 50.
C: Caution when wet: Sunscreen should no longer be labeled as “waterproof” but will instead say “water-resistant” and will include the maximum time it will be effective in water, usually 40 or 80 minutes. This language is more accurate than previous language because no sunscreen is truly waterproof and it needs to be reapplied frequently, which is reiterated by the timing given on the label. It’s also worth mentioning that “sport” sunscreen effectively protects you even when sweaty as long as it’s applied prior to sweating so that it can bond to the skin’s surface. 
D: Do it all day long: No matter what brand you buy, all sunscreens need to be reapplied throughout the day to be effective. It’s smart to reapply an amount that would fill a shot glass to the exposed areas of the body (face, arms, and legs) at least every couple of hours. For those who have trouble remembering to reapply when you’re out in the sun, new smart phone apps can alert you when it’s time to slather on more. There are also devices you can wear that can tell you when you’ve reached the maximum amount of UV exposure you should receive that day—so you know when it’s time to go inside. Usually UV rays are strongest between 11 a.m. and 2 p.m. so it’s best to avoid being outside during that time if possible. 
In Rochester and around upstate New York, every day of sunlight is a gift, but for unprotected skin, sun causes more harm than good. Anything you can do to help protect your skin from burns and tans will reduce your chances of getting skin cancer not while keeping your skin looking younger for longer. 
Sherrif Ibrahim MD
Sherrif Ibrahim, M.D., Ph.D., is a dermatologist with UR Medicine’s Wilmot Cancer Institute. His focus is on the diagnosis, treatment, and prevention of skin cancer.