CHICAGO — Despite recommended limits on codeine use in children, the potent painkiller is prescribed for children in at least half a million emergency room visits each year, a study suggests.

Use of the drug in that setting is hardly rampant — just 3 percent of kids’ ER visits resulted in a codeine prescription in 2010, the 10-year study found. But with more than 25 million ER visits by children each year, the authors say far too many kids are getting the drug when better options are available.