MONDAY, Sept. 28 (HealthDay News) -- More than half a million kids a year are treated for medication side effects in American outpatient clinics and emergency rooms, according to new data.

Researchers at Children's Hospital Boston analyzed National Center for Health Statistics outpatient data between 1995 and 2005. Among children up to age 18, there were 585,922 visits a year for adverse drug events (ADEs). Most visits were to outpatient clinics, but 22 percent were to hospital emergency departments.

"We found that there are as many as 13 outpatient visits for adverse drug events per 1,000 children, indicating that they are a common complication of pediatric care," study leader Dr. Florence Bourgeois, of Children's division of emergency medicine, said in a news release.

The majority of visits were by children 4 and younger (43 percent), followed by youngsters aged 15 to 18 (23 percent). Skin-related (45 percent) and gastrointestinal (16.5 percent) were the most common types of side effects, and 52 percent of the children had symptoms that suggested an allergic reaction.

Antimicrobials such as penicillin were the most frequently implicated drugs. They were involved in 27.5 percent of all visits and in as many as 40 percent of visits by children under 4.

The two next most frequently implicated drugs were neurologic/psychotropic medications (6.5 percent) and hormones (6 percent). These two categories of drugs accounted for the most visits among older children, which likely reflects their increased use for emotional and behavioral disorders by teens and for birth control among teen girls.

The study findings, published in the October issue of the journal Pediatrics, suggest that doctors need to be aware of the potential adverse effects of medications in children and provide appropriate information to parents, the researchers said.

"One approach to reducing adverse events is to ensure that clinicians have ready access to complete information on the adverse effects and comparative effectiveness of medications. This information should derive from data on the real-world use of the drugs, not just from the package inserts," Bourgeois said.

More information

The U.S. Food and Drug Administration has more about children and medications.