The calls were from worried parents, emergency room doctors and others seeking advice on how to deal with the problem, which can be deadly. Four deaths were among cases evaluated in the study, based on data from 1998 to 2005.

The findings have been released Monday in the August edition of the journal Pediatrics.

Kids taking ADHD drugs to get high or increase alertness may not realize that misuse of the drugs can cause serious, sometimes life-threatening symptoms, including agitation, rapid heartbeat or extremely high blood pressure.

"They say, 'It's FDA approved, how dangerous could it be?"' said Steve Pasierb, head of The Partnership for a Drug-Free America, based in New York.

In the study, researchers from Cincinnati Children's Hospital Medical Center evaluated 1998-2005 data from the American Association of Poison Control Centers. During that time, nationwide calls related to teen abuse of ADHD drugs, specifically stimulants, increased from 330 to 581 yearly, and there were four deaths.

Overall, 42 percent of teens involved had moderate to severe side-effects and most ended up getting emergency-room treatment.

The true number of teen abusers who have bad side effects is likely much higher, because many cases don't result in calls to poison control centers, said study author Dr. Randall Bond, medical director of the hospital's Drug and Poison Information Center.

The surge, from 1998 to 2005, outpaced calls for teen substance abuse generally. It also paralleled an 86 percent rise in ADHD medicine prescriptions for kids aged 10 to 19, from about 4 million to nearly 8 million during that time.

Mark Stein, a psychiatry professor and ADHD expert at University of Illinois at Chicago, said abuse typically involves crushing and snorting the pills, which speeds up the effects and can produce a buzz or sense of euphoria - along with dangerous side effects.

Stein said the study should not deter use of ADHD drugs in teens who really need them, particularly since there's evidence that kids with ADHD who don't get medication are at risk for abusing illicit drugs.

Government-sponsored surveys suggest that teen abuse of stimulants including ADHD drugs has declined in recent years.

©2009 by The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.