Many of the body's organs, including the heart, kidneys, lungs and liver, depend on serotonin, a chemical that the drugs block to treat depression.
Around one in eight Americans are taking an SSRI (selective serotonin reuptake inhibitor) drug, such as Prozac, and they could be at increased risk of premature death, say researchers from McMaster University, who took another look at previously-published studies that involved many hundreds of thousands of people.
Lead researcher Paul Andrews said: "We are very concerned by these results. They suggest that we shouldn't be taking antidepressant drugs without understanding precisely how they interact with the body."
Far from being life-savers, the drugs could be killers, with any benefits of reduced depression more than offset by a higher risk of death. "I think people would be much less willing to take these drugs if they were aware how little is known about their impact outside of the brain, and that what we do know points to an increased risk of death," said another researcher, Marta Maslej.
As for the rest, the drugs could be doing more harm than good.