Yasmin, Yaz birth control pills may increase clot risks

Birth control pills such as Yasmin and Yaz may be associated with up to three times the risk of blood clots compared with other oral contraceptives, according to a Health Canada review.

The department announced Monday that it has completed a safety review of oral contraceptives containing drospirenone, sold under the brand names Yasmin and Yaz.

"Overall, the body of current evidence suggests that the risk of blood clots is 1.5 to 3 times higher with oral contraceptives that contain drospirenone relative to those that contain levonorgestrel, a different hormone," Health Canada said in a release.

The risk of blood clots with any oral contraceptive, including Yasmin and Yaz, is very small, it said.

"To put this into perspective, if the estimated risk of developing a blood clot among women taking a levonorgestrel-containing birth control pill is 1 in 10,000 women per year, as some studies have estimated, then the risk in women taking a drospirenone birth control pill is about 1.5 to 3 women in 10,000 per year."

The drug labels have been updated to include information on the studies.

The label also recommends that when health professionals prescribe an oral contraceptive that they consider the risks and benefits of drospirenone-containing oral contraceptives for a specific patient in light of her risk for developing blood clots, and relative to the risks and benefits of other birth control pills on the market, Health Canada said.

In a CBC Marketplace investigation earlier this year, Bayer said its product Yasmin was no riskier than any other oral contraceptive on the market.

On Thursday, the U.S. Food and Drug Administration's reproductive health drugs advisory committee will meet to discuss the risks and benefits of oral contraceptives containing drospirenone.