SP-Huh? Here’s How to Decode Sunscreen Labels

With so many brands of sunscreen crowding the store shelves, manufacturers have to work hard to garner their fair share of the market. Some of them even resort to downright untruths, so avoid any sunscreen that makes claims like these on its label:

It’s waterproof and/or sweatproof. Nonsense. According to the FDA, it’s technically impossible for any sunscreen to be waterproof or sweatproof. A product may be water-resistant, but only if it retains its original sun protection factor (SPF) after at least 40 minutes in water.

It’ll last all day. Hogwash. Dermatologists recommend reapplying sunscreen every two hours, and more frequently if you’ve been sweating heavily or you’ve been swimming.

The higher a sunscreen’s SPF number is, the more protection it gives you — right? Right — but only up to a point. The SPF measures the percentage of UVB rays that a sunscreen blocks. For example, SPF 15 blocks 93 percent of rays, 30 blocks 97 percent, and 50 blocks 98 percent. If you see a number higher than that, don’t waste your money—any extra blocking action will be minimal. To achieve optimal protection, choose an SPF between 30 and 50.

For years, sunscreen manufacturers have touted their products’ ability to guard against the sun’s damaging UVB rays. Well, guess what? UVA rays can be even worse. While UVB rays do burn your skin and put you at risk for skin cancer, UVA rays penetrate deeper. Not only can they cause other types of skin cancer, but they also damage collagen, thereby accelerating the aging process. The bottom line: Always buy sunscreen labeled “full-spectrum,” which means it’s been proven to protect against both kinds of rays.