Yaz has been linked to various side effects, but a new Canadian study is suggesting that the pills can also be linked to irritable bowel syndrome (IBS). The study was conducted by researchers at the University of British Columbia and was published online at Stanford University’s Highwire.

Researchers used this study to compare drospirenone-based pills like Yaz and Yasmin to older birth control pills that don’t contain drospirenone. The results of the study showed that the drospirenone-based pills can be linked to IBS. For the study, the researchers analyzed information collected from nearly 1 million women between the ages of 18 to 46. They learned that the women who were taking Yaz and Yasmin were nearly twice as likely to develop IBS than those who took pills that were levonorgestrel-based. Nearly 1 percent of the women in the Yaz group developed the IBS within 90 days, compared to the less than half a percent of women in the non-Yaz group.

Irritable bowel syndrome causes changes in the digestive system that alter bowel habits. IBS can also cause patients to suffer from chronic diarrhea or constipation. The condition is very debilitating and can cause bloating and abdominal pain. Yaz, Yasmin and other drospirenone-based pills have long been linked to numerous serious conditions including heart attacks, strokes, gallbladder disease and blood clots. The drug’s new links to IBS may cause many more Yaz users to file lawsuits against the makers of the pills, Bayer. To date, more than 11,000 lawsuits have already been filed against Bayer over Yaz, and more continue to be filed. Bayer has recently reached settlement agreements in at least 500 cases against it to the tune of $110 million, and it is possible that more settlements may be in the company’s future since patients continue to suffer from Yaz-related injuries, and studies continue to back up the plaintiffs’ claims.