Misunderstanding prescription drug labels is a recognized source of errors in ambulatory care. Low health literacy places patients at higher risk, and language barriers may also contribute to preventable medication errors, as illustrated vividly in an AHRQ WebM&M commentary. A prior study found that translated drug labels are available in many pharmacies, but this study found that Spanish-language labels generated by commercial translation systems are disturbingly inaccurate. Half of the labels contained at least one error, and the authors document examples of incomplete or inaccurate translations that could lead to serious patient harm (for example, "once a day" mistranslated as "eleven times per day"). A prior study also found that Spanish-speaking patients may be at higher risk of experiencing errors while hospitalized.