What is known: Some medications carry significant side effects. Stimulants may be associated with a slower rate of growth when used consistently over several years. Antipsychotics are linked to rapid weight gain and metabolic and endocrine abnormalities. In one study, kids ages 2 to 6 gained an average of 19 pounds in less than 12 weeks on one antipsychotic-drug regimen. But even with these side effects, doctors defend the drugs' use in the most severe cases. “This doesn't mean children shouldn't be on these medications—many have benefits that outweigh the risk of side effects,” says Rachel Klein, M.D., director of the Anita Saltz Institute for Anxiety and Mood Disorders at New York University. “It does mean you need to be really careful to monitor kids who are on these drugs.”

For parents whose lives have been turned upside down by intensely moody or rebellious toddlers and preschoolers, the psychiatric drugs can seem heaven-sent. “My son used to be a ticking time bomb—he'd find a screwdriver and poke a hole in the screen door, then stuff a toy down the toilet in a matter of minutes,” says Theresa Newfield of Raynham, MA, whose son Dayson was diagnosed with ODD when he was 3. Now on the stimulant Adderall (amphetamine and dextroamphetamine) by day and an antidepressant before bed, “Dayson can actually focus on what you're saying and reply with a sensible thought,” she says.

Last year The New York Times reported on a boy named Kyle who started taking an antipsychotic drug when he was just 18 months old, prescribed by a physician trying to control the boy's severe temper tantrums. The article documented the child's journey from doctor to doctor, diagnosis to diagnosis, until, by the time he was 3, he was taking an antipsychotic, an antidepressant, two sleeping medicines, and a drug for attention deficit hyperactivity disorder. Now 7, the boy was finally weaned off all meds but one—for ADHD—through a program administered by the state of Louisiana in partnership with Tulane clinicians.

“The rate that children are being medicated is increasing out of proportion to research showing that it's safe and effective,” says Mary Margaret Gleason, M.D., assistant professor of psychiatry and behavioral sciences at Tulane University School of Medicine. “At the same time, we know that kids need help.” Dr. Gleason, who treated Kyle as he was weaned off the heavy medications, said there was no valid reason to give antipsychotic drugs to the boy…or virtually any other 2-year-old.

About 1 in 5 children ages 13 to 18 has some sort of mental disorder, be it an anxiety, mood, or disruptive behavior disorder, according to researchers at the National Institutes of Health. The rate of problems in preschoolers is not much less than that of teens, says Dr. Gleason. That means there are a lot of children who desperately need help. But are these medications the best way for them to get it?