Reference — Pharmacology
Look-Alike / Sound-Alike Medications
Look-alike/sound-alike (LASA) medications are drugs whose names look or sound similar to other medications. LASA confusion is consistently identified as a leading cause of medication errors. The ISMP maintains a curated list of high-risk LASA pairs.
Educational use only. This reference is for clinical learning. The ISMP LASA list is updated regularly — refer to ismp.org for the current version. Always clarify ambiguous medication names before administration. This material supports nursing education and exam review. It is not medical advice and is not a substitute for clinical judgment, institutional policy, or medical direction. Always follow facility protocols and current provider orders.
Why LASA Errors Happen
LASA errors occur across every step of the medication use process — prescribing, transcription, dispensing, and administration. Contributing factors include:
- Similar drug names that differ by only one or two letters (e.g., hydralAZINE vs. hydrOXYzine)
- Similar-looking drug packaging or label design
- Handwritten or poorly typed orders where individual letters are ambiguous
- Verbal orders where phonetically similar names are misheard
- Alphabetical proximity in electronic dropdown menus — selecting the wrong drug when the name is partially typed
- High workload, interruptions, and fatigue reducing attention to detail
Common LASA Pairs — High Risk
Tall-man lettering (mixed uppercase) is used to highlight the differing portions of similar drug names.
| Drug A | Drug B | Use A | Use B | Risk if Confused |
|---|---|---|---|---|
| hydralAZINE | hydrOXYzine | Antihypertensive | Antihistamine / anxiolytic | Hypotension vs. sedation |
| DOBUTamine | DOPamine | Heart failure (inotrope) | Vasopressor / dopaminergic | Wrong hemodynamic effect |
| EPINEPHrine | EPHEDrine | Anaphylaxis, cardiac arrest | Bronchospasm, hypotension | Profound cardiovascular effects |
| predniSONE | predniSOLONE | Anti-inflammatory (oral) | Anti-inflammatory (various) | Dosing inequivalence |
| cycloSERINE | cycloSPORINE | Antibiotic (TB) | Immunosuppressant | Organ rejection vs. toxicity |
| vinCRIStine | vinBLAStine | Leukemia / lymphoma | Testicular cancer / lymphoma | Different toxicity profiles |
| glipiZIDE | glyBURIDE | Sulfonylurea (diabetes) | Sulfonylurea (diabetes) | Hypoglycemia risk differs |
| clomiPHENE | clomiPRAMINE | Fertility (ovulation induction) | OCD / depression (TCA) | Completely different indications |
| metFORMIN | metroNIDAZOLE | Type 2 diabetes | Antibiotic / antiprotozoal | No antidiabetic effect |
| carBAMazepine | oxCARBazepine | Seizure / bipolar | Seizure | Dosing and interactions differ |
| morphine | hydroMORPHone | Opioid analgesic | Opioid analgesic (more potent) | Hydromorphone ~5× more potent — 10-fold dosing errors |
| Novolin R (regular insulin) | Novolin N (NPH) | Short-acting insulin | Intermediate-acting insulin | Wrong onset/duration — hypoglycemia risk |
Prevention Strategies
At the bedside (nursing)
- Read the full drug name on the label — not just the first few characters
- Always scan the barcode with BCMA before administration; do not bypass alerts
- When receiving a verbal order for a LASA drug, spell the drug name back and state the indication
- Verify the indication matches the drug — if morphine is ordered for pain but you pull a drug used for fertility, stop
- Question orders that seem inconsistent with the patient's condition or care plan
System-level safeguards
- Tall-man lettering — capitalizing differing portions of LASA names (e.g., hydralAZINE vs. hydrOXYzine) in the EHR and on labels
- Physical separation — LASA drugs stored in separate locations with warning stickers
- CPOE alerts — EHR systems may flag LASA pairs during order entry
- Pharmacy review — pharmacist verification catches LASA errors before dispensing
Related References & Guides
Standards & sources
Fact-checked Jun 20, 2026This page is written to align with Institute for Safe Medication Practices (ISMP) · FDA prescribing information · The Joint Commission — National Patient Safety Goals. It is an educational summary, not a citation of any single document — always verify specific doses, values, and protocols against current guidelines and your facility policy. How we source content →