Foundation makeup with sunscreen tends to lose the ability to shield the skin from the sun after a few hours, according to a report in the Journal of the American Academy of Dermatology (Vol. 45, No. 4: 542-543).

"Patients who rely on their facial foundation for [sun protection] should be advised to reapply the product at least every two hours," wrote study author Zoe D. Draelos, MD, at Wake Forest University School of Medicine in Winston-Salem, N.C.

In her study, Draelos applied three different kinds of common facial foundation makeup (a lotion, a liquid, and a cream/powder) to the faces of 12 women.

She then used a microscope with video to provide a very close-up look at how well the makeup stayed in place. The test took eight hours, and was conducted in typical office or home conditions of 74-degree temperature and 40% humidity.

Draelos discovered that the foundation stayed in place at first, but soon began to move and gather in fine lines and in pores.

None of the different kinds of makeup was still evenly covering the face four hours after it was applied.

Draelos noted many women rely on makeup for sunscreen because it contains sunscreen ingredients, but cautioned that outside a lab makeup might spread or come off even more quickly.

A skin cancer expert with the American Cancer Society (ACS) agreed.

"The study is well done and reaches a reasonable conclusion," said Martin A. Weinstock, MD, PhD, at Brown University and chair of the ACS skin cancer advisory board.

Weinstock said that better protection can be had by first applying sunscreen — the ACS recommends a sunscreen with an SPF (sun protection factor) of at least 30 — and applying foundation once the sunscreen has been absorbed into the skin.

That way, even if the foundation shifts and leaves some areas of the skin uncovered, the skin still will have some protection from the underlying sunscreen.

But Weinstock said it's important not to rely on any one method — such as sunscreen — to keep skin protected from the kind of sun damage that can lead to skin cancer.

"Slip, slop, slap is the American Cancer Society slogan, and it's a good one," said Weinstock, reminding people to slip on some protective clothing, slop on sunscreen, and slap on a hat.

Skin cancer melanoma rates are increasing at a more rapid pace than any other cancer in the US, noted Weinstock. It can occur anywhere on the body where skin is exposed to ultraviolet light from the sun.

And protection is not just for summertime, said Weinstock.

"People need to remember that if they're going be outdoors this winter, they need to protect themselves, because you can get really intense sun on the face with the reflection off the snow," said Weinstock.

It's useful to know what inherited traits such as skin type or hair color might make you more at risk for skin cancer, Weinstock said, but very important to remember that anyone can get it.

And it's most important to do what's necessary to protect your skin from skin cancer, he added.

"By protecting your skin from sun damage, you can have fun outdoors without having to worry about harm showing up later to spoil those great memories," concluded Weinstock.