Women were warned Wednesday that their risk of blood clots in the legs and lungs may be higher if they use the birth-control patch instead of the pill.

The Food and Drug Administration said it updated the label on the Ortho Evra birth-control patch to reflect the results of one study that found women using the patch faced twice the risk of clots than did women on the pill. However, a second study found no difference in risk between the two forms of birth control.

“Even though the results of the two studies are conflicting, the results of the second epidemiology study support FDA’s concerns regarding the potential for Ortho Evra use to increase the risk of blood clots in some women,” the FDA said in a notice published on its Web site.

Initial results of the two studies were made public in February by the patch’s manufacturer, Ortho Women’s Health & Urology. The Raritan, N.J.- based company is owned by Johnson & Johnson.

Last year an investigation by The Associated Press, citing federal death and injury reports, found higher rates of blood clots in women using the patch.

The FDA recommended that women with concerns about clots and use of the patch talk to their doctors.

“We cannot conclude there is in fact a greater risk,” Shames said. “We are however concerned enough about this information and we think it is important enough information that it should be given to consumers and to healthcare providers so they can make better choices.”

In November, the FDA updated the label on Ortho Evra to alert women that using the patch exposes them to about 60 percent more estrogen than using birth control pills.

Johnson & Johnson previously has said clots remains rare and that they have been reported as a potential risk of all hormonal contraceptives.

Ortho Women’s Health & Urology said in a statement that data will continue to be collected for both studies. Shames said the studies, which rely on insurance claims information on upward of 500,000 women, would last another 18 to 24 months.

The company also said it would continue to provide new information to the FDA.

The company reported in findings made last month that Ortho Evra sales have declined significantly following the previous label revision and a spare of media coverage of the clot tissue. Since the patch went on sale in 2002, more than 4 million women have used it.

The company also disclosed that approximately 500 people have filed lawsuits or made claims related to injuries they allegedly suffered from the Ortho Evra patch.

The investigation by The Associated Press found that patch users die and suffer blood clots at a rate three times higher than women taking the pill. About a dozen women died in 2004 from blood clots believed linked to use of the patch, the AP reported. Dozens more suffered stroked and other clot-linked problems.

Health officials warn that women who smoke should not use the patch, since smoking increases the risk of stroke and heart attack. Researchers believe estrogen may promote coagulation of the blood.