photos of woman wearing sunscreen and moisturizer This image shows SPF 30 moisturizer (left) and SPF 30 sunscreen (right), photographed by a special camera. The lighter an area looks, the less successful the absorption of UV light. (Photo: The University of Liverpool)

It's just so easy: When you're prepping for the day, you slather on moisturizer that contains sunscreen. There's no reason to use two different products when one double-duty cream can do the work of both.

But new research from The University of Liverpool finds that moisturizers with sun protection factor offer less sun protection than the same-strength SPF sunscreen. In addition, people are more likely to miss parts of their face when applying them.

For the study, researchers used a modified camera that registers only ultraviolet light. When an area of the face is covered well, the product absorbs UV light, so the area appears black in photos. The lighter an area appears in an image, the less successfully the product was absorbed.

Sixty volunteers were asked to apply sun protection on two different visits: first with SPF 30 sunscreen, and then with SPF 30 moisturizers. Photos were taken with the modified camera to determine how well people applied the products. The research was presented at the British Association of Dermatologists' annual meeting in Edinburgh in early July.

When researchers analyzed the photos, they found that people missed 16 percent of their face on average when they applied moisturizer with sunscreen. When they applied straight sunscreen, however, they missed only 11 percent. There was an even greater discrepancy in the eyelid area, which is a common spot for skin cancer. Sunscreen users missed 14 percent of that area, compared to moisturizer users who missed 21 percent.

How you apply it matters

Woman applying moisturizing skin cream to her face looking in bathroom mirror People don't usually apply moisturizer as thickly as sunscreen, so they don't get the full SPF benefits. (Photo: Voyagerix/Shutterstock)

People also tended to apply the moisturizer less thickly than sunscreen, so they didn't get the full coverage of the SPF. Overall, the photos of people using moisturizer are lighter, showing the product is absorbing less UV light.

"We expected the moisturizer to perform worse than the sunscreen on overall protection, as it seemed intuitive that people apply moisturizer quite thinly on the whole. While we were correct in this, the research did throw up some unexpected surprises," researcher Austin McCormick, consultant ophthalmic and oculoplastic surgeon, said in a statement.

"We thought that people would miss more of their face with the sunscreen, as we’ve all had that stinging sensation when you accidentally rub some in your eye and we expected that this would lead people to be conservative and avoid the eyes. Actually, people missed more of their face when using the moisturizer."

In addition, the researchers found that men were better at applying both products than women, as were older participants and people with darker skin tones.

"Although moisturizer with SPF does provide sun protection, our research suggests that it’s not on the same level as sunscreen," McCormick said. "We would not recommend it as a like-for-like replacement for your sun protection needs.”

Mary Jo DiLonardo covers a wide range of topics focused on nature, health, science and anything that helps make the world a better place.

You're betting on moisturizer with sunscreen to save your skin. You shouldn't.
Study finds that moisturizer with sunscreen isn't as effective as straight sunscreen.