Those who use the popular acne drug, which Roche stopped selling last June but remains available as a generic, have almost twice the odds of developing IBD as those not taking the pill, according to a new study, The Los Angeles Times reports.

At the annual meeting of the American College of Gastroenterology in San Diego last week, the paper writes, researchers from the University of North Carolina, Chapel Hill, presented evidence showing a higher rate of IBD, which is characterized by intestines that become chronically red and swollen, producing pain, cramping, diarrhea, weight loss and bleeding

They compared 8,189 cases of IBD with 21,832 healthy individuals and found the odds of developing such diseases were 1.68 times higher those who took the acne drug. Those who filled four or more prescriptions had 2.67 times the risk. The odds of having ulcerative colitis were 4.36 times higher. (No increased risk was found for Crohn’s disease, perhaps the most severe such ailment.)

But only about 5 to 10 people in 100,000 are diagnosed with inflammatory bowel disease each year, according to Crockett.”The absolute risk of getting inflammatory bowel disease is very low,” he tells the paper. “So if someone has disfiguring acne that was affecting their quality of life, it might be a risk they are willing to take.”

A similar study, published in July in the American Journal of Gastroenterology by University of Manitoba researchers, found no such association, the Times notes. That study examined a large database in Canada and found that 1.2 percent of people diagnosed with IBD had used the drug before diagnosis, compared with 1.1 percent who had not used isotretinoin.

There is no biological explanation for why isotretinoin might increase the risk of IBD, Crockett says, adding: “There are a lot of things that are not understood.”

In a statement, Roche reiterated earlier remarks that its decision to withdraw Accutane reflected market pressures and the cost of lawsuits, not safety concerns. Meanwhile, the drugmaker faces some 500 lawsuits in federal and state courts claiming Accutane causes IBS, as well as depression and suicide (latest story). Plaintiffs have won an estimated $33 million in judgments against Roche for bowel disorders, according to an industry publication, Dermatology Times.