Children on medication for attention-deficit hyperactivity disorder (ADHD) may rarely experience psychiatric symptoms such as hallucinations reported a recent study. Clinical trials and post-marketing reports of side effects from the commonly prescribed ADHD stimulant medications, such as Concerta, Ritalin and Strattera were reviewed by U. S. government experts and they found that out of every 100 "person-years" of treatment, one or two children will experience serious side effects, such as hallucinations of bugs or snakes.

FDA experts reviewed the results of 49 randomized trials of ADHD medication and placebos undertaken to evaluate the potential psychiatric side effects of these drugs. The researchers reported that there were 11 episodes of psychosis or mania seen for every 743 person years of treatment, while no episodes of psychosis or mania were seen in children on placebos.

The study reported that for every 100 person years the rate of psychosis or mania was 1.48. Person-years is defined as total years of treatment with a drug and 100 people taking the drug for one year is called 100 person-years. An analysis of spontaneous adverse-event reports to the FDA showed more than 800 reports of psychosis or mania.

Published today in the journal Pediatrics, the study found in about 90 % of cases, there was no previous history of a similar psychiatric condition, and psychotic symptoms were found with every ADHD drug tested. The most common hallucinations were visual or tactile sensations of insects, snakes or worms and they disappeared once the children stopped taking the ADHD medication.

"Patients and physicians should be aware that psychosis or mania arising during drug treatment of attention-deficit hyperactivity disorder may represent adverse drug reactions, the study's authors wrote."These reactions are very rare," said Dr. Roy Boorady, director of the psychopharmacology service at the New York University Child Study Center in New York City. "We see a lot of children on medications here, and I would say maybe one a year or once every two years, we might hear about a child with tactile hallucinations, where kids feel like they have bugs on them. It's usually really young kids who are on medications, and once they back off or stop the medications, the sensation is gone," he said.

Dr. William Cohen, a developmental-behavioral pediatrician in the Child Development Unit at Children's Hospital of Pittsburgh said, "Any medication has side effects, some of which are very, very rare. Whenever your child is taking any new medication, if something new starts, consider it a side effect and call your doctor. With these medications, it's safe to stop them and call your doctor." He added that he felt parents should not be overly concerned about the possibility of psychiatric symptoms, because they are so uncommon. (Additional reporting by Harkiran)