When you walk into a doctor’s office, you are more likely to be prescribed an antidepressant than almost any other class of drug. In fact, you’re likely already on one.Since the late 80s, antidepressant use has increased fivefold, with women more than twice as likely to take them as men. Upwards of 30 million Americans now take them regularly, filling more than 253 million prescriptions for antidepressants in 2010 alone.But for all their promises of youthful energy and eternal sunshine (you’ve seen the commercials), the list of caveats and side effects is a little, well, depressing.MORE: Which Type of Therapy is Right for You?Now, a new study from McMaster University in Ontario takes those side effects to task. Looking at the effects of antidepressants in a number of previous patient studies, the researchers found that antidepressants likely do more harm than good.The reason came down to a little chemical called serotonin, considered lacking in people with mood disorders, such as depression or anxiety.Antidepressants are typically designed to boost serotonin in the brain, which helps to regulate mood. But the drugs also increase serotonin in other parts of the body, especially the gut. That’s where things go awry.“Serotonin is a really ancient chemical that’s actually involved in a huge number of processes,” explains lead author and evolutionary biologist Paul Andrews, Ph.D. Off the top of his head, he lists development, mood, attention, blood clotting, behavior, and gastrointestinal and reproductive functions. “Antidepressants have negative effects on each of these body processes.”MORE: Treating DepressionIndeed, Andrews’ team found a litany of increased risks: developmental problems; abnormal bleeding and stroke; digestive problems like diarrhea, constipation and bloating; headaches; and problems with sexual function and sperm development. “It seemed intuitive to us that this laundry list would probably outweigh the beneficial effects, which are often not much at all,” says Andrews.However, he wasn’t convinced until he found that antidepressants make elderly patients more likely to die—even after controlling for other variables, including depression. “It’s hard to argue that a drug is doing more good when it actually increases the risk of death,” says Andrews.While this news may seem surprising, the war over antidepressants has been raging for years.In 2009, a landmark review in the Journal of the American Medical Association found that, in many cases, antidepressants are no better than placebos. Only in very severe cases did the antidepressants work better than sugar pills—and even then the effect was moderate.Other studies have found similar results and a major review co-authored by Aaron Beck in 2005 found that cognitive behavior therapy, a structured style of talk therapy that targets self-defeating thoughts, was “somewhat superior to antidepressants in the treatment of adult depression.”That doesn’t mean you should throw your pills down the drain, especially since controlled experiments are yet to confirm Andrews’ findings.“There’s a huge placebo effect in depression,” says Andrews. “Antidepressant drugs do work, but arguably not because of the chemical properties of the drugs. Most of it is contributable to the placebo effect. You get symptom reduction just by seeking help.”YOUTALK: What Helps You Through a Hard Time?