Back when it was “suntan lotion” instead of “sunscreen” the numbers on the bottles designed to let us have our sun and keep from burning were 4 or 6. Then came 15 as people grew more concerned with skin cancer than perfecting their tans. Now you can pick up sunscreen with a sun protection factor (SPF) of 75 or even 100. Do you get more than three times as much protection with a 100 SPF sunscreen than with 30?
The math doesn’t work that way, explains Michelle Bichchau Nguyen, MD, MPH, a dermatologist who is Director of Dermatologic Surgery at Tufts Medical Center. Because SPF 30 already blocks 97 percent of the sun’s rays, there isn’t much room for improvement with higher SPFs. That’s why the American Academy of Dermatology recommends SPF 30 or higher. And a higher SPF doesn’t mean the sunscreen works longer.
“People shouldn’t be fooled into thinking that just because you use SPF 100 you don’t have to reapply,” Dr. Nguyen says. “What matters is that you use it consistently and that you apply every two hours if you’re out in direct sun.”
How much you use is also important. Adults should use a shot-glass-size amount to cover their faces, necks, ears, forearms and legs—but most of us don’t. “I don’t even use that much myself, to be honest,” says Dr. Nguyen.
SPF(SUN PROTECTION “FACTS”)
To protect against skin cancer and premature aging of the skin, Dr. Nguyen recommends the following:
- Use a sunscreen of SPF 30 or higher daily (but there’s really no need for ultra high SPFs).
- Apply every two hours if you’re in the sun; apply more often if you’re in the water or sweating, even with a water-resistant sunscreen.
- Use spray or lotion—it doesn’t really matter—but it needs to be applied according to directions.
- Consider clothing impregnated with sunscreen— it can be expensive, but works great— “especially for men and kids, since they hate spreading creams on their skin,” says Dr. Nguyen