There’s a reason the topic is so testy: As with many beauty queries, there isn’t a straight-up answer. So we turned to three dermatologists to help break it down. Many have raised concerns that a moisturizer may dilute the SPF component, rendering it not as effective. As board-certified dermatologist Jeanine Downie, M.D., says, “I definitely feel that moisturizer combined with sunscreen decreases the effectiveness of sunscreen.” Although, perhaps it’s less about the formula itself and more about user behavior: Namely, moisturizers with SPF typically aren’t as water-resistant, so they might not work as well if you’re swimming or sweating. Maybe that’s where the moisturizer-sunscreen gets its diluted reputation—it might lose effectiveness once there’s water involved. But the product itself, says board-certified dermatologist Hadley King, M.D., isn’t so much of an issue. After all, plenty of market sunscreens include emollients to lend a creamier application (especially for those sometimes chalky mineral sunscreens) and antioxidants to calm inflammation—aka, ingredients you may find in your everyday moisturizer. “There’s a spectrum of how moisturizing the formulations are, as well as what other active ingredients there are, like antioxidants,” King adds. “As long as there are humectants, emollients, and occlusives, the formulation will be moisturizing.” These ingredients don’t typically dilute the standard sunscreens (albeit, at lower concentrations), so why would they yield a less-than-stellar moisturizer-sunscreen? Also, any product on the market that boasts SPF must be adequately tested before that number gets stamped on the label. Says King, “It’s not like they took a sunscreen of a certain SPF and then diluted it with moisturizer—the finished product must be tested to determine its SPF.” Where it becomes dicey is with makeup: Half of a teaspoon of tinted moisturizer or foundation with SPF is quite a lot of product, and you might not necessarily want that much base coverage. That’s all fine, but you should use a proper sunscreen underneath in that case. People may remain in their two equally fervent camps, but assuming you’re following correct application instructions, you can do what’s best for your skin—that’s the golden rule.
