Background: Medication errors (MEs) are an important cause of preventable harm but remain insufficiently quantified in emergency care. This study assessed the frequency, characteristics, and clinical impact of MEs among adverse drug reaction (ADR)–related emergency department (ED) admissions in Germany. Methods: We conducted a prospective multicenter study across six EDs between 2015 and 2021 (n = 7967). ADRs and MEs were classified using standard causality (World Health Organization-Uppsala Monitoring Centre (WHO-UMC)) and preventability criteria (Schumock). Patient, medicine, symptom, and outcome characteristics were compared between ADRs caused by MEs and ADRs without documented MEs. Regression models assessed factors associated with ME involvement among ADR cases and length of hospital stay. Results: 20.1% of ADR-related cases involved an ME. Clinical presentation, symptom burden, triage severity, and discharge outcomes were similar between groups. MEs clustered around commonly used chronic medications, including pantoprazole, torasemide, metoprolol, ramipril, phenprocoumon, and ibuprofen. Schumock analysis showed preventability as primarily linked to dosing errors (30%), non-adherence (28%), contraindications (26%), and monitoring (20%). Medicine-specific symptom clusters mirrored expected pharmacological effects but were not specific to ME involvement. Multimorbidity was associated with slightly lower odds of ME attribution, although the estimate was borderline (OR 0.84, 95% CI 0.71–1.00); no robust associations were identified for the other patient-level characteristics examined. Adjusted length of hospital stay was slightly longer in cases involving MEs (+4.8%; p = 0.025), corresponding to an adjusted difference of 0.33 days. Conclusions: MEs were identified in a substantial proportion of ADR-related ED admissions. Most MEs arose from routine prescribing and monitoring processes involving commonly used medicines, suggesting that preventive efforts should focus on upstream safeguards, including medication reviews, electronic prescribing support, pharmacist involvement, and adherence support, rather than detection at emergency presentation.

Background: Medication errors (MEs) are a frequent cause of preventable harm but remain insufficiently quantified in emergency care. This study assessed the frequency, characteristics, and clinical impact of MEs among adverse drug reaction (ADR)–related emergency department (ED) admissions in Germany. Methods: We conducted a prospective multicenter study across six EDs over six years (n=7,967). ADRs and MEs were classified using standard causality (World Health Organization-Uppsala Monitoring Centre (WHO-UMC)) and preventability criteria (Schumock). Patient, drug, symptom, and outcome characteristics were compared between ADRs with and without MEs. Regression models assessed predictors of MEs and length of stay in hospital. Results: 20.1% of ADR-related cases, involved a preventable ME. Clinical presentation between groups; symptom burden, triage severity, and discharge outcomes, were similar. MEs clustered around chronic medications (pantoprazole, torasemide, metoprolol, ramipril, phenprocoumon, ibuprofen). Schumock analysis showed preventability as primarily linked to dosing errors (30%), non-adherence (28%), contraindications (26%), and monitoring (20%). Drug-specific symptom clusters mirrored expected pharmacology but were not error-specific. Multimorbidity was modestly protective (OR 0.84, 95%CI 0.71–1.00), while age, sex, polypharmacy, and number of diagnoses were not. Length of hospital stay was slightly longer in ME cases (+0.37 days; p = 0.037). Conclusion: MEs were identified in a substantial proportion of ADR-related ED admissions. Most MEs arose from routine prescribing and monitoring processes involving commonly used drugs suggesting that preventive efforts should focus on upstream safeguards, including medication reviews, electronic prescribing support, pharmacist involvement, and adherence monitoring, rather than detection at emergency presentation.