Birth control patch-wearers at higher risk of blood clots

Users of the Ortho Evra birth control patch (Ortho McNeil Pharmaceuticals) are exposed to higher overall levels of estrogen than users of birth control pills and thus may be at higher risk for blood clots and other serious side effects, according to the FDA.

Recently updated labeling for the product now states that women who use Ortho Evra are exposed to about 60% more total estrogen in their blood than women taking a typical birth control pill containing 35 μg of estrogen. This is because hormones from the patch enter the bloodstream directly, while pills are swallowed and digested first, losing about half their estrogen dose in the process. While the peak blood level of estrogen is about 25% lower with the patch than with the Pill, estrogen levels with the patch remain relatively constant for about 1 week until the patch is removed, whereas peak blood levels with the Pill, which generally occur within 1 or 2 hours of taking it, rapidly decline over a 12-hour period to levels that are lower than with the patch. This means the body is not exposed to high levels of estrogen 24 hours per day.