Roughly 7 percent of adults and 19 percent of children taking chemotherapy drugs as outpatients or at home were given the wrong dose or experienced other mistakes involving their medications, according to a new study.

An analysis of data on nearly almost 1,500 patient visits at four oncology outpatient clinics showed that errors in medication were more common than previously reported.

Of the 90 medication errors involving adults, 55 had the potential to harm the patient and 11 did cause harm. More than 50 percent of errors involving adults were in clinic administration, 28 percent in ordering of medications, and 7 percent in use of the drugs in patients' homes. About 40 percent of the 22 medication errors in children had the potential to cause harm and four children were harmed. Examples of pediatric errors included children being given the wrong dose or the wrong number of doses per day of medicines.