TUESDAY, July 25 (HealthDay News) -- A new sunscreen just approved by the U.S. Food and Drug Administration promises protection for the full range of both ultraviolet A and B rays.

However, that doesn't mean people can disregard standard advice to avoid the sun and still protect their skin, experts stressed.

Anthelios SX, made by L'Oreal, is new in that it contains ecamsule (Mexoryl), an agent that shields skin from short-wave UVA rays -- something sunscreens currently available in the United States are unable to do. The product will be available to consumers this fall.

"There is nothing like this in the U.S.," said Dr. Darrell S. Rigel, a clinical professor of Dermatology at New York University and advisor to L'Oreal. "Basically, it lasts longer, and it gives better protection against UVA."

But a better sunscreen doesn't change the basic rules of skin protection.

"No sunscreen completely protects people against UVA radiation," said FDA spokeswoman Kimberly A. Rawlings. "This product and other sunscreens reducing UVA exposure should be used in conjunction with limiting time in the sun and wearing protective clothing. FDA has not compared this product with other sunscreens capable of reducing UVA exposure."

According to experts, UVB causes sunburn and skin cancer, while UVA causes aging and some skin cancers. Most sunscreens currently contain two active ingredients: avobenzone and octocrylene. Anthelios SX, which has an SPF of 15, contains those compounds as well, but adds in Mexoryl. Sunscreens containing Mexoryl have been available in Europe, Asia and Canada since 1993.

Why it has taken so long for the FDA to approve the product is not clear.

Rigel noted that most UVA protections are not chemically stable and breakdown quickly. "What Mexoryl does is stabilize them and make them last longer," he said.

While the retail price of Anthelios SX is not known, four-ounce sunscreens containing the same ingredients sell elsewhere for about $40.

One expert believes the best sun protection combines physical sun blocks with chemical ones.

"A lot of sunscreens break down in the sun. That's the dirty little secret that no one talks about," said Dr. Jeffrey C. Salomon, an assistant clinical professor of plastic surgery at Yale University School of Medicine. "In most sunscreens, there are both chemical and physical sun blocks."

Sun blocks such as zinc oxide and titanium physically block the sun from coming in, Salomon said. "Chemical sun blocks break down rapidly in the sun," he said. "You want a sunscreen that blocks both UVA and UVB, that has a high SPF, and that is waterproof."

"It's best to use a sunblock that contains both physical as well as chemical blockers," Salomon advised. Salomon recommends putting a shot-glass-size amount of sunblock on each arm and leg and on the chest and back. In addition, it should be put on at least 30 minutes before going into the sun and reapplied every two hours.

More information

For more on skin cancer, head to the U.S. National Cancer Institute.