These popular drugs use a version of a female hormone which appears to reduce side effects that are found in older drugs, effects such as bloating and mood swings. But, the FDA is also reviewing research on clot risks associated with Johnson & Johnson’s weekly Ortho Evra patch, which uses a different version of the female hormone progestin.
Millions of women have used these products since they introduced a decade ago, but recent studies comparing the medical histories of women taking the new drugs to older ones suggest a slightly higher risk of blood clots in the legs and lungs. While all hormone-based drugs increase the risk of clotting, the matter is further complicated in that clots can be caused by factors such as smoking, obesity, or family history.
Last year, the U.S. market for female contraceptive drugs totaled $3.4 billion, but sales of Yaz have fallen since safety questions began to draw scrutiny. Yaz, the best-selling birth control pill in the U.S. for 2008 and 2009, was further forced to correct advertisements that overstated its benefits. Between 2007 and 2010, Bayer, makers of Yaz, spent more than $270 million on TV and magazine advertisements.
While Bayer says that its studies have shown no difference in blood clot risk between its drugs and older birth control, the large, independent studies suggest that the risk with Yaz and similar medications is slightly higher. The latest FDA estimates that the risk of a blood clot with these types of drugs translates into an estimated 10 in 10,000 women on the newer drugs experiencing a blood clot, as compared to 6 in 10,000 women on the older contraceptives.
Some doctors are stating that even with the additional warning labels, they do not expect to stop prescribing them, and the risk of blood clots with any birth control pill is still far lower than the risks associated with pregnancy and birth, as hormone levels and reduced blood flow increase clotting risk as well.