A group of Canadian women are filing a lawsuit against the makers of Bayer's popular oral contraceptives Yaz and Yasmin, alleging they were not adequately warned about higher than usual risks for stroke and other health problems.

The pills, sold under the name Yaz and Yasmin, are used by thousands of Canadian women and teens. For most, they work well. But some users are reporting racing hearts, strokes and, in some cases, gallbladder problems leading to surgery.

One of those launching the suit is Christine Lovelace. The Halifax woman says after she began taking Yaz last February (for reasons beyond birth control), she developed strange symptoms. She started getting heart palpitations, she says, waking up in the middle of the night with her heart racing, and unusual menstrual changes, with periods lasting as long as 14 days.

Her doctors thought the 42-year-old was suffering from anxiety or entering menopause. They told her not to worry.

Then, last fall, Lovelace had a TIA stroke (transient ischemic attack, or "mini-stroke").

"I went paralyzed all down my left side and I lost my ability to communicate. It was terrifying," she remembers.

She stopped taking the pill and says her symptoms disappeared. She recovered from the stroke but still has some nerve damage in her hand and foot.

She says she hopes her lawsuit brings attention to the side effects of these pills.

"I guess I am trying to raise awareness that if you have all these strange symptoms complications and you don't feel right, talk to your doctor," she says.

Jennifer Demunnik also took Yaz. She first tried Yasmin, but didn't like the way it made her feel, so switched to Yaz, which contains a lower dose of estradiol.

When she suddenly developed severe abdominal pain about a year and a half after starting the pill, doctors found she had developed gallstones. They told the 27-year-old her gallbladder would need to be removed.

After her surgery, Demunnik went online and found other women taking Yaz and Yasmin who had similar complaints. She also found reports that some 1,100 lawsuits had been filed in the U.S. involving these pills.

All contraceptives carry the risk of side effects, including severe ones such as blood clots and stroke, especially in women with risk factors such as women who smoke or have high cholesterol. Demunnik says she knew about the risks but believes there are higher risks with the Yaz and Yasmin brands that she was not properly warned about.

"And I just think well, you know what? People, women need to be aware of this," she says.

Siskinds LLP filed the lawsuit Wednesday against Bayer Inc., the maker of Yaz and Yasmin, though it has not yet been court-certified.

Matthew Baer, a lawyer at Siskinds, says his firm has heard lots of reports of health concerns potentially linked to the pills.

"We're hearing about pulmonary embolisms, deep vein thrombosis, stroke and, a more unusual one, people having issues with their gallbladders," he says.

Yasmin and Yaz were approved by Health Canada in 2004 and 2008 respectively. The pills have become bestsellers among teens and young women. More than 2 million prescriptions were filled in Canada in 2009, reports IMS Health Canada.

The brands have been heavily promoted as a contraceptive that can also help control acne as well as the symptoms of PMS, or premenstrual syndrome.

The lawsuit claims that while all birth control pills carry risks, Yaz and Yasmin carry higher risks compared to other brands, because they contain a newer formulation that uses the hormone drospirenone.

Bayer says drospirenone helps prevent acne and counteracts estrogen-induced water retention, leading to less bloating and breast tenderness.

But the hormone can also increase potassium in the blood. If potassium levels become dangerously high, some studies suggest it can lead to heart rhythm problems.

The lawsuit's statement of claim alleges that Bayer failed to adequately warn patients and doctors about the increased risk of serious adverse injuries associated with use of Yasmin and Yaz as compared to safer oral contraceptives.

"We would also like to get the warning changed so that we have a proper warning for people going forward," Baer says.

Bayer contends its oral contraceptives "have been and continue to be extensively studied worldwide and are safe and effective when used according to the product labeling."

"Bayer reaffirms and stands behind the safety of its drospirenone-containing oral contraceptives," the company said in a response to CTV News.

As for the lawsuits, Bayer said it is "in the process of gathering information on these cases, but the complaints we have reviewed so far pertain to side effects that are warned about in the labeling of all oral contraceptives, including ours. Bayer will defend itself vigorously against these lawsuits."

The Society of Obstetricians and Gynaecologists of Canada advises all women currently using oral contraceptives not to suddenly stop taking them and continue using them as prescribed, unless they experience complications.

"If you have specific concerns regarding the oral contraceptive you are using, please speak to your health-care professional," the group advises in an email to CTV News.

Baer say his hope is that the lawsuit will compel Bayer to explain to Canadian consumers what it knew about the risks associated with using Yasmin and Yaz and when it first became aware of those risks.

For Lovelace and Demunnik, they say their lawsuit is not about money or damages; it's about warning other women.

"I think really I need doctors to be aware, if patients are complaining that they are not feeling quite right," says Lovelace. "Pay attention and don't just pooh- pooh it."

With a report from CTV medical specialist Avis Favaro and producer Elizabeth St. Philip