Medication errors
Medication errors are the most preventable cause of patient harm in healthcare. Understanding how they occur — and where pharmacists, prescribers, and systems can intervene — is a core clinical competency.
Error Classification
The National Coordinating Council for Medication Error Reporting and Prevention (NCC MERP) ↗ classifies errors by severity:
Categories A–B are near misses. C–I represent errors that reached the patient.
Types of Medication Error
Wrong dose, wrong drug, wrong indication, missing allergy check, failure to renally adjust.
Clinical decision support (CDS) alerts in EMR, pharmacist order review, dose range checking.
Decimal point errors (1.0 mg misread as 10 mg), trailing zeros, unclear abbreviations (U misread as 0).
Ban dangerous abbreviations (U, IU, QD), require leading zeros (0.5 mg not .5 mg), electronic prescribing.
Wrong drug selected from LASA name pairs, wrong concentration of same drug, wrong patient label.
Barcode verification at dispensing and bedside (BCMA), physical separation of LASA pairs, tall-man lettering.
Wrong route (oral dose given IV), wrong time (missed or duplicate dose), wrong infusion rate.
Smart pump libraries with hard limits, bedside barcode scanning (BCMA), two-nurse independent double-checks for high-alert drugs.
Failure to check TDM levels (vancomycin, digoxin), failure to monitor INR during warfarin initiation.
Structured TDM protocols, pharmacist-managed anticoagulation and antibiotic dosing services, electronic monitoring alerts.
Home medications omitted on admission, unintentional drug duplication at discharge, wrong dose carried forward.
Structured medication reconciliation at every care transition (admission, transfer, discharge) — a pharmacist-led process.
High-Alert Medications
The ISMP high-alert medications list ↗ identifies drug classes with the greatest potential for serious patient harm when errors occur. These drugs require additional safeguards beyond standard practice.
| Drug / Class | Error Type Most Likely | Key Safeguards |
|---|---|---|
| Insulin | 10-fold dose errors; "units" misread as "0" | Never abbreviate "units"; independent double-check; standardised sliding scales |
| Anticoagulants (heparin, warfarin, DOACs) | Wrong dose, wrong drug, missed bridging | Pharmacist-managed anticoagulation service; INR monitoring; renal dose check for DOACs |
| Concentrated KCl (≥2 mEq/mL) | IV push administration causing cardiac arrest | Remove from ward stock; require pharmacy preparation; smart pump library |
| Opioids | Respiratory depression from dose errors or accumulation | Opioid stewardship; dose conversion reference; PDMP check; naloxone co-prescribing |
| Neuromuscular blocking agents | Administration to non-intubated patient | Segregate storage; remove from ward stock; distinctive labelling |
| Methotrexate (oral) | Daily dosing instead of weekly | Label as "weekly dose"; patient and prescriber education; annual dose limit tracking |
| Chemotherapy agents | Wrong dose (BSA calculation error), wrong cycle | Pharmacy-only preparation; independent pharmacist double-check; 2-pharmacist sign-off |
| Hypertonic saline (NaCl 23.4%) | Central line required; rapid infusion causes osmotic demyelination | Pharmacy preparation only; infusion rate limits in smart pump library |
Look-Alike / Sound-Alike (LASA) Drugs
LASA name confusions are a leading cause of serious medication errors. The ISMP confused drug names list ↗ is updated regularly and should be used to guide storage separation and labelling practices.
Both insulins — different onset/duration
Different potencies; paediatric dosing error risk
Completely different classes
Different chemotherapy dosing — can be fatal
Antihypertensive vs benzodiazepine
Antihypertensive vs antihistamine
Tall-man lettering (capitalising distinguishing letters) is recommended by ISMP and FDA to highlight differences in similar-looking names.
Reporting Channels
Report medication errors and near misses to drive system improvement. Key channels:
Medication Errors Reporting Program — voluntary, confidential, national database
Voluntary adverse event and error reporting to FDA — patients and professionals
Standardised error reporting formats for hospital patient safety organisations
Sentinel event reporting for errors causing serious harm or death — required for accredited hospitals