Health Canada is reviewing the safety of Bayer's birth control pills Yaz and Yasmin over concerns that they might raise women's risk of blood clots more than other birth control pills.
Although all hormonal birth control pills raise the risk of clots, Health Canada's review focuses on Yaz and Yasmin because both contain drospirenone.
The agency is currently reviewing two new studies recently published in the British Medical Journal that found that women aged 15 to 44 taking drospirenone-containing birth control pills were more likely to develop venous thromboembolism -- blood clots that develop in the deep veins of the legs -- than women using older pills containing the common progestin levonorgestrel.
The studies suggest that the risk of blood clots with drospirenone-containing birth control pills may be two to three times greater than with other pills.
"Currently, Health Canada is evaluating the recently published studies and it is looking at all available information to fully assess the risk of blood clots. Health Canada will take appropriate action as necessary once the review is complete," the agency said in a statement.
This could include informing health professionals and Canadians of new safety information resulting from Health Canada's review.
Bayer has criticized the results of those studies, and insists that side effects are rare. They also claim that "the risk ... is comparable to other birth control pills studied."
"Bayer's oral contraceptives have been and continue to be extensively studied worldwide and for most healthy women of reproductive age, the benefits of (combined oral contraceptives) will outweigh the risks, when used as directed," the company recently said in a statement.
The U.S. Food and Drug Administration is also reviewing the studies, but suggested it remained cautious about the latest findings.
"Other studies have not reported an increase in risk. The FDA is currently evaluating the conflicting results from these studies and will look at all currently available information to fully assess the risks and benefits of drospirenone-containing birth control pills," the agency said last week.
The European Medicines Agency concluded on May 27 that the pills carry a higher risk of venous thromboembolism. It ordered that warning labels be updated accordingly. However it stopped short of advising women to stop taking pills containing drospirenone.
Health Canada says women with questions or concerns about their oral contraceptive should talk to their doctors.
"Patients should be aware that stopping their birth control may result in unintended pregnancy," it reminded.
As well, patients who think they are experiencing symptoms of a blood clot should seek immediate medical attention and mention any medications they may be taking, including birth control pills. Symptoms of a blood clot may include persistent leg swelling, leg pain or tenderness, chest (thoracic) pain, or sudden shortness of breath.
Although birth-control pills raise the risk of blood clot, the absolute risk is still very low.
Health Canada reminds birth control pills are not recommended in patients with a history of blood clots. As well, women over the age of 35 who smoke are also at an increased risk of blood clots and should not take the pills.
Yaz and Yasmin have been the focus of more than 1,000 lawsuits in th U.S., including one lodged earlier this month on behalf of a teenager who died from a blood clot allegedly linked to the contraceptive.
There is also a large, ongoing class action lawsuit in Canada which has yet to be certified. According to the law firm running that case, about 600 Canadian women have contacted them, listing a host of health problems they believe are linked with the pills.
"About 200 of those women have complained about gallbladder disease, over 150 have required surgery to remove their gallbladder. We've also had about 200 people with blood clots, and most of those are deep vein thrombosis or pulmonary embolism, which is a blood clot in the lungs," says lawyer Matthew Baer.
