WASHINGTON — Safety concerns about the popular birth-control pill Yaz increased Thursday as federal health scientists reported that the Bayer drug and other newer birth-control treatments appear to increase the risk of dangerous blood clots more than older medications.
A new study released by the Food and Drug Administration (FDA) reviewed the medical history of more than 800,000 U.S. women taking different forms of birth control between 2001 and 2007. On average, women taking Yaz had a 75 percent greater chance of experiencing a blood clot than women taking older birth-control drugs.
Yaz contains estrogen along with a next-generation synthetic hormone called drospirenone, which is known to increase potassium in the blood. The FDA compared medical records of women taking the drug with those taking the older drug levonorgestrel.
Yaz, Yasmin and related drospirenone-containing pills were Bayer's second-best-selling franchise last year at $1.6 billion in global sales.
In 2009, the FDA took the unusual step of ordering Bayer to run corrective TV advertisements on Yaz, saying the drugmaker's marketing campaign overstated the drugs' ability to prevent acne and premenstrual syndrome.