No rest for the Food and Drug Administration (FDA) this week. In addition to considering broadened access to the emergency contraceptive Plan B, an FDA panel decided on Thursday to update labeling on Bayer’s popular Yaz and similar birth control pills to better reflect the higher risk of blood clots associated with these drugs, compared with older oral contraceptives.
After reviewing the medical evidence, the federal panel voted 21-5 on Thursday that labeling on Yaz, Yasmin, Beyaz, Safyral and its generic versions is inadequate and should be revised. The panelists said the label should make clearer the potential risk of blood clots in the legs and lungs from taking the pills, and that clots can be fatal. The labeling now only informs women about the conflicting studies on the blood-clot risks.
In a separate deliberation, the panel members made clear that they were themselves conflicted about the quality of the existing evidence, voting 15-11 that the drugs’ benefits as a contraceptive outweighed their risks.
At issue is a newer synthetic form of progesterone called drospirenone, which is used in Yaz, Yasmin and similar birth control pills. Two large studies conducted by Bayer have shown no difference in blood clot risk between women taking the company’s drugs versus those taking older birth control pills. But five other independent studies have found a slightly higher risk in women taking the drospirenone-containing medication. One recent FDA-funded study found that the risk was in fact nearly 75% higher.
The absolute risk of developing a blood clot is still low, however. FDA researchers found that the rate of blood clots was 10 in 10,000 women taking pills with drospirenone, compared with 6 in 10,000 women taking older oral contraceptives. By contrast, the blood-clot risk in women who are pregnant or have just given birth is 20 in 10,000 women. But small increases in risk are serious, since blood clots can cause potentially fatal heart attacks, strokes and pulmonary embolisms.
The panelists noted, however, that the recent data were incomplete, since studies didn’t take into account factors like smoking, weight, family history or other lifestyle factors than can affect risk of blood clots. The FDA paneled called for better, more conclusive research going forward.
Yaz, approved in 2006, was initially marketed to younger women with the catchy tagline “beyond birth control.” Ads highlighted the drug’s lifestyle benefits — like clearing acne and preventing premenstrual symptoms — over older oral contraceptives. The marketing worked: within two years, Yaz had become the most popular birth control pill in the U.S., reaching sales of $781 million in 2009, the AP reports. But recent safety concerns over blood clots have dramatically cut prescriptions. (Bayer was also forced to roll back its overblown claims about the drug’s effects on PMS and acne.)
So far, doctors don’t seem to be worried about new labeling recommendation, noting that the medical evidence on blood-clot risk isn’t conclusive and that the overall risk is too small to cause concern. Still, about a third of the FDA panel disagreed, voting that the drugs’ benefits did not outweigh their potential harm — especially considering that there are so many other alternatives on the market.
“I can see no real group of patients that this drug benefited over existing alternatives,” Mark Woods of New York University School of Medicine told the AP. “Without any clear benefit, and given the potentially catastrophic risk, I voted no.”
The panel did not give a deadline for the label update. While the FDA can choose to accept or reject the panel’s recommendation, it typically follows their counsel.
Meredith Melnick is a reporter at TIME. Find her on Twitter at @MeredithCM. You can also continue the discussion on TIME’s Facebook page and on Twitter at @TIME.