The study, reported online in Alimentary Pharmacology & Therapeutics, also found that when the drugs -- serotonin reuptake inhibitors or SSRIs -- are taken with non-steroidal over-the-counter or prescription anti-inflammatory drugs, or NSAIDs, such as aspirin, Aleve, Celebrex and and pain medications -- the risk is more than 600 percent higher.

The combined use of NSAIDs and SSRIs may have a synergistic effect, which results in the elevated risk of bleeding beyond that seen with each agent alone, Dr. Sonal Singh, of Wake Forest University School of Medicine, in Winston-Salem, N.C., said.

"Clinicians who prescribe these medications should be aware of the potential risk and may need to consider alternatives," Singh said in a statement.

Singh pooled clinical data from four studies involving 153,000 patients and analyzed 101 U.S. and Canadian adverse effects reports and found bleeding linked to SSRI use occurred after a median of 25 weeks on the drugs. Sixty-seven percent of those patients were also taking NSAIDs. The majority of adverse reactions occurred in the elderly who took both types of drugs.