LASA Errors: How Look-Alike, Sound-Alike Drugs Cause Mistakes and How to Stop Them

When a patient gets the wrong drug because two names look or sound too similar, that’s a LASA error, a type of medication mistake caused by drugs with similar names or packaging. Also known as look-alike, sound-alike errors, these aren’t rare accidents—they’re preventable failures that land people in the hospital every day. Think of Hydralazine and Hydroxyzine. One lowers blood pressure. The other treats anxiety. Mix them up, and you could trigger a stroke or a dangerous drop in blood pressure. These aren’t hypotheticals. The FDA tracks hundreds of these cases each year, and most happen in hospitals, pharmacies, and even at home when prescriptions are misread.

LASA errors don’t just happen because someone typed wrong. They’re fueled by systems that don’t account for human error. Generic drugs make this worse. Take Bactrim, a common antibiotic containing sulfamethoxazole and trimethoprim and Bicitra, a citrate-based drug used for acid reflux. The names start the same. The bottles look alike. The pills might even be the same color. Without clear labeling or double-checks, pharmacists and nurses grab the wrong one—and patients pay the price. Older adults on multiple meds, patients in busy ERs, and those with poor vision or hearing are most at risk. Even a tiny typo in an electronic system—like swapping "D" for "B"—can switch a drug entirely.

It’s not just about names. Packaging matters. Two drugs with nearly identical bottle shapes, font sizes, or color schemes can fool even experienced staff. That’s why hospitals now use tall-man lettering—writing HYDROxyzine and HYDRAlazine—to force the eye to notice the difference. Barcode scanning, electronic alerts, and mandatory double-checks for high-risk drugs cut these errors by up to 70%. But not every clinic has those tools. And not every pharmacy trains staff to slow down when a drug name sounds familiar.

You don’t need to be a doctor to help. If you’re taking multiple pills, read the label every time. Ask your pharmacist: "Is this the same as the last one I got?" If the name looks or sounds like another drug you’ve taken, speak up. Write down your meds in plain language. Keep a list. And never assume the pill looks right just because it’s the same color. The system isn’t perfect—but you can be the last line of defense.

Below, you’ll find real-world examples of how these mix-ups happen, what went wrong, and how people just like you learned to spot the warning signs before it was too late.