A birth control skin patch used by many American women carries a risk of serious blood clots that is higher than the risk already recognized for the birth control pill, the U.S. Food and Drug Administration warned late Friday.
Based on the results of a new study that discovered the increased danger, the agency said it has approved changes to the labeling for the Ortho Evra Contraceptive Transdermal Patch, to better warn women and their doctors of the potential risk.
"For women that choose to use contraceptives, it is important that they thoroughly discuss with their health-care providers the risks and benefits involved," Dr. Janet Woodcock, deputy commissioner for scientific and medical programs at the FDA, said in a statement.
The warning followed reports out of Canada last week of two deaths, one heart attack and 16 cases of blood clots since 2004 among women who used the patch.
Approved by the FDA in 2001, the patch is sold by prescription and releases ethinyl estradiol (a type of estrogen), and a progestin called norelgestromin via the skin into the bloodstream. But the FDA noted that the body processes hormones delivered in this way differently than hormones delivered in pill form, so that "women using the product will be exposed to about 60 percent more estrogen than if they were using typical birth control pills."
Blood clots called venous thromboembolisms (VTEs) -- which can travel to the lungs as life-threatening pulmonary embolisms -- have long been known to be a rare but potential side effect of the birth control pill, and for the patch as well. In fact, the FDA had already revised the Ortho Evra label once in 2006, after a study found it doubled women's odds for VTE. Another study found use of the birth control patch boosted women's odds for the clots by about the same amount as did the Pill.
However, an epidemiological study just conducted by the Boston Collaborative Drug Surveillance Program, on behalf of drug maker Johnson & Johnson -- has found the patch may carry an even higher clotting risk than the Pill does.