Children who have attention deficit hyperactivity disorder (ADHD) could find their height stunted by the medications used to treat this condition.

The results of a study and two years of follow- up research by scientists at the University of California, Irvine, found that stimulant medications used to treat ADHD are effective, but they may slow growth in height a bit.


The randomized clinical trial, which lasted 14 months, compared the use of the stimulant medication methylphenidate (Ritalin) with behavioral therapy. Both Ritalin alone and behavioral therapy alone were also compared with a combination of two and with no treatment at all.

Researchers found that the children who received medication or medication in conjunction with behavioral therapy had fewer symptoms than those who received no medication. Children on medication also grew slightly less than their non-medicated peers.

James Swanson, a psychologist and professor of pediatrics at the University of California, Irvine, and his colleagues then followed up with 540 children with ADHD who had participated in the trial.

After 24 months, the researchers interviewed the children and the parents and found that both the effects of medication and the effects of behavioral therapy were fairly consistent throughout this time period.

They also confirmed that the children who were on medication showed a slight reduction in height, but according to Swanson, the effect was less pronounced at 24 months, amounting to approximately one centimeter less per year than the children who were not taking medication.


"Stimulant medications are really extremely safe with very few side effects," says Swanson. "I do not think this is necessarily a cause for great alarm in parents. The effect we saw was rather modest."

Swanson also notes that many questions remain unanswered.

For example, researchers don't know if children on ADHD medications will have a growth rebound later.

He adds that many children who have ADHD are larger than average for their age, so the slight growth reduction for those on medication may just put them back into the normal height range.

Dr, Ernest Krug, medical director of Beaumont Hospital's Center for Human Development in Royal Oak, Michigan, says, "Growth suppression is something we always monitor in kids on medication. This study reinforces the importance of careful follow-up of children when they're on medication. It's a good idea for these children to be seen every three to four months."

With any medication, parents should be convinced that the drug is providing beneficial effects for their children without causing unreasonable side effects, Krug says.

To learn more about ADHD, visit the Children and Adults with Attention Deficit/Hyperactivity Disorder (CHADD) Web site at

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