Recent studies have documented an increase in emergency department visits and deaths due to medication errors in outpatients. Such studies may be limited in their ability to provide a true picture of adverse drug events in the ambulatory setting, as the majority of medication errors are handled by poison control centers. This analysis of data from the National Poison Data System characterized more than 1 million out-of-hospital medication errors and found that only 7.5% required referral to a physician. Most errors involved nonprescription medications such as cough and cold medications, and dosing errors were frequently reported (similar to a prior study in a pediatric population). Reducing outpatient medication errors will require new approaches to patient education, especially in populations with low health literacy.