“People were about 10 times more likely to burn on the SPF 50 side than the SPF 100 side,” Rigel says. Given the results, the researchers concluded that SPF 100 is “significantly more effective in protecting against sunburn than SPF 50.” That said, there’s more to choosing a sunscreen than an SPF number. Read on for the words you should always look for on your label.

Are there any downsides to using a high SPF sunscreen? 

There is a catch (well, several) when it comes to higher SPF. First, while an SPF above 60 may offer greater protection again UVB, due to photochemistry, it typically has less UVA protection, Dr. Ciraldo tells Allure. And, trust us, you should be worried about both. 

“UVA rays penetrate even more deeply and are responsible for most skin aging, hyperpigmentation, damage to collagen fibers, and more aggressive skin cancers including melanomas,” Dr. Ciraldo notes. It’s for this reason, she says, that the FDA is now strongly considering guidelines to make 60 the highest SPF you can buy.

There’s also the danger that a higher SPF number will impart a false sense of security. “People believe that if they have an SPF 100 they have significantly increased protection so they can stay out in the sun for longer without reapplying their sunscreen,” says Dr. Ciraldo.

Another reason she isn’t a fan of SPF 60 plus sunscreens is “the higher levels of chemicals,” says Dr. Ciraldo. Concerns around avobenzone have been bubbling up for some time, with the FDA still reviewing its safety alongside 11 other chemical filters that absorb into the body. That said, cosmetic chemist Laura Lam-Phaure doesn’t believe there is reason for alarm. 

“A higher SPF doesn’t necessarily correlate with having an increased concentration of chemical actives like avobenzone,” she says. “In an optimal sunscreen formula, photo-stabilizers, emollients and antioxidants all contribute to the SPF value, spreadability, and stability of the final formulation,” she adds.

If it’s not broad-spectrum, don’t buy it.

When choosing a sunscreen to purchase, all of our experts recommend looking for the words “broad spectrum” on the bottle.

“This means that your sunscreen offers both UVB and UVA protection,” says board-certified dermatologist David Kim, M.D. It’s one way to ensure that you get adequate UVA protection because not all sunscreens have PA ratings (more on that later) in the US, he adds.

In short, even if you’re using a high SPF sunscreen, if it isn’t broad-spectrum, you’re better off applying a lower-strength sunscreen that is, says Dr. Zeichner. “I would rather you choose an SPF 15 product that protects against UVA rays and UVB rays as opposed to a higher SPF that doesn’t give you UVA protection,” he adds.

What about Korean sunscreens?

According to Lam-Phaure, South Korean sunscreen formulas are advancing at a fevered clip compared to the U.S. “The FDA considers sunscreens over-the-counter drugs, so formulators are limited with what ingredients they can use,” Lam-Phaure tells Allure. “The addition of any new active ingredients to the Title 21 Monograph, which regulates these drugs, would require extensive testing,” she adds. Yet Asian sunscreen formulators now have filters like Tinosorb at their disposal, which delivers a double-whammy by protecting against both UVA and UVB rays. “In fact, the last time the FDA made any decisions regarding sunscreens was in the 1970s,” says Lam-Phaure. “It’s unlikely that’ll we see new approved UV filters any time soon due to a lack of FDA funding for the cosmetics sector, as well as a lack of data,” she notes.