Patients who take antidepressants around the time of surgery are at increased risk of bleeding, hospital admission and even death, according to a study in the April 29 issue of JAMA Internal Medicine.

Researchers from the University of California San Francisco and Baystate Medical Center in Springfield, Mass., say selective serotonin reuptake inhibitors (SSRIs) — Prozac, Paxil and Zoloft, to name a few popular options — interfere with blood cells that promote clotting, which could lead to excessive bleeding.

The researchers reviewed the medical records of more than 530,000 patients who underwent surgery at 375 hospitals between 2006 and 2008, a large data set that they say lends credibility to their findings.

They concede patients who take SSRIs are more likely to have conditions or traits that increase surgical risk, including obesity, chronic pulmonary disease and depression, but conclude antidepressants are independent risk factors.

A prospective observational study is needed to further verify the findings, warns Andrew Auerbach, MD, MPH, the study's lead author and a professor of medicine at UCSF. He also says patients shouldn't be advised to stop taking antidepressants before undergoing surgery, but the increased dangers should be discussed with surgeons or primary care physicians.

Daniel Cook