Objectives Errors in prescribing can cause avoidable harm to patients. Establishing the extent of prescribing errors across medical specialties is critical. This research explores the frequency and types of prescribing errors made by healthcare professionals prescribing for patients with renal disease where prescribing problem-solving and decision-making is complex due to comorbidity.

Methods All prescriptions and errors made by prescribers were captured over a 4-month period in a UK renal unit. Data were recorded concerning the medicine associated with the error, the type and severity of the error, and the prescriber's occupational grade.

Results 10 394 prescribed items were captured and 3.54% had associated prescribing errors. While Foundation Year 1 doctors made almost one error each week (mean 15.13) and Foundation Year 2 doctors one every 2 weeks (mean 8.00), other prescribers made one error per month (mean 3.94). The medicines most frequently associated with errors for Foundation doctors were paracetamol (6.51%), calcium acetate (5.33%), meropenem (3.55%), alfacalcidol (3.55%) and tazocin (3.55%), while for all other prescribers they were meropenem (6.15%), alfacalcidol (4.62%), co-amoxiclav (4.62%) and tacrolimus (4.62%). The most common types of error for both groups were omitting the indication, using the brand name inappropriately, and prescribing inaccurate doses.

Conclusions The range of errors made by multi-professional healthcare prescribers confirms the complexity of prescribing on a renal unit for patients with kidney disease and multimorbidity. These findings have implications for the types of educational interventions required for reducing avoidable harm and overcoming human factors challenges to improve prescribing behaviour.