Newer antidepressants, already suspected of raising the risk of suicide in some patients, may also cause a few people to become violent, researchers reported on Monday.

They found that people who took GlaxoSmithKline’s antidepressant Paxil were twice as likely to have what was called a “hostility event” as those given a placebo.

Paxil, known generically as paroxetine, is in a class of drugs called selective serotonin reuptake inhibitors. or SSRIs. They came under scrutiny when some doctors reported that teenagers taking the drugs might be more likely to commit suicide.

In 2004, the U.S. Food and Drug Administration concluded there was a higher risk of suicidal behavior among children and teenagers and ordered strong label warnings on several SSRI drugs. It has urged close monitoring of adults.

David Healy and David Menkes from Cardiff University in Britain and Andrew Herxheimer from the Cochrane Center used several sources of information to see what the risk of violent behavior was among people taking SSRIs.

This included paroxetine data presented to Britain’s Committee on Safety of Medicines Expert Working Group by GlaxoSmithKline, legal cases, and e-mails from 1,374 patients in response to a British television program on the subject.

They found that 60 out of 9,219 people who took Paxil, or 0.65 percent, had “a hostility event,” compared with 20 of 6,455 given a placebo, or 0.31 percent.

Writing in the online journal Public Library of Science Medicine, the researchers noted that such violence was likely to be rare. “The new issues highlighted by these cases need urgent examination jointly by jurists and psychiatrists in all countries where antidepressants are widely used,” they wrote.

“When violence is a suspected outcome, every case has to be considered carefully, on the principle that individuals are responsible for their conduct, unless there is clear evidence of compromised function that cannot be otherwise explained.”