Objectives To quantify medication-related errors, in particular prescribing errors, identified by pharmacists and assess their potential impact on inpatients in community hospitals.

Methods Pharmacists recorded all interventions to optimise medication for community hospital inpatients over 14 days in November 2013. Interventions were subsequently classified by type (prescribing error; omitted or delayed drug administration; or attributable to other issues) and rated for potential clinical impact.

Results 15 organisations participated in the study reporting on 4077 medication charts. In total, 52 033 medication orders were screened by pharmacists. A medication-related intervention was made on 1 in 3 charts for one or more medications. A total of 2782 interventions were recorded. The majority were categorised as a prescriber error (67%, 1872/2782). The remainder (33%, 910/2782) were not directly attributable to prescriber error; of these omitted and delayed medicine administration accounted for 11% (298/2782). Of the 1872 interventions classed as prescriber error, a third, if left undetected, might have caused moderate or severe patient harm. The prescribing error rate was 3.6 errors per 100 medication orders.

Conclusions Pharmacists reported intervening to improve the care provided to over a third of patients in this study. Two-thirds of interventions were in response to prescribing errors, a third of which, if left undetected, could have led to harm. The results suggest that inpatients in community hospitals are subject to prescribing errors at a rate comparable to those seen in acute and mental health hospitals. A clinical pharmacy service is vital to ensure patient safety in community hospitals.