How to Identify Look-Alike Names on Prescription Labels

Every year, thousands of patients in the U.S. and UK receive the wrong medication-not because of a mistake in dosage, but because two drug names look or sound too similar. Look-alike and sound-alike (LASA) drug names are one of the most dangerous, yet overlooked, risks in healthcare. A patient meant to get hydralazine for high blood pressure might end up with hydroxyzine, an antihistamine used for allergies. The difference? Just a few letters. And in a busy hospital or pharmacy, those letters can disappear in a blur.

These errors aren’t rare. Studies show that about 1 in 1,000 prescriptions involves a LASA mix-up. Of those, more than one-third reach the patient, and nearly 1 in 15 causes real harm-like falls, allergic reactions, or even heart problems. The problem isn’t just handwritten scripts or tired staff. It’s built into the system. Drug names are often created without enough thought to how they’ll be confused in real-world settings.

What Is Tall Man Lettering-and Why Does It Matter?

The most common tool to fight LASA errors is called tall man lettering. It’s simple: capitalize the parts of drug names that differ. So instead of writing hydroxyzine and hydralazine, you write hydrOXYzine and hydrALAzine. The capital letters act like visual signposts, forcing your eyes to pause and compare.

The FDA started pushing for this in 2001 after a string of deadly mix-ups. Today, 35 drug pairs are officially recommended for tall man lettering, including:

• doXEPamine vs. doBUTamine
• CISplatin vs. CARBOplatin
• vinBLAStine vs. vinCRIStine
• INSULIN lispro vs. INSULIN glargine

It’s not just about capitalization. The FDA recommends capitalizing 2-4 letters that create the clearest visual contrast. Too few, and it doesn’t help. Too many, and it looks messy. The goal is to make the difference obvious at a glance-even if you’re tired, rushed, or under bright fluorescent lights.

But here’s the catch: tall man lettering only works if it’s used everywhere. A pharmacist might see hydrOXYzine on the computer screen, but the printed label from the automated dispenser shows hydroxyzine in all lowercase. That’s when errors happen.

How to Spot LASA Names in Practice

If you’re a nurse, pharmacist, or even a caregiver helping someone manage medications, here’s how to catch these errors before they happen:

1. Always read the full name-not just the first few letters. Many mix-ups happen because people skim. Valtrex and Valcyte both start with “Val,” but one treats herpes, the other a serious viral infection. The full name matters.
2. Look for capital letters in electronic systems and printed labels. If you don’t see them, ask why. Many older printers or EHR systems don’t apply tall man lettering automatically.
3. Compare brand and generic names. For example, Valtrex is the brand name for valacyclovir, and Valcyte is for valganciclovir. Seeing both names together reduces confusion by over half, according to ECRI Institute data.
4. Check the purpose. Is this medication for pain, infection, or heart failure? If the reason doesn’t match the drug, pause. A 2022 study found that adding the purpose (e.g., “for shingles”) to the label cuts errors by nearly 60%.
5. Use the 3-step rule: Read the label when you pick it up, read it again when you hand it off, and read it one more time before giving it to the patient. This simple habit reduces errors by more than half.

Why Technology Alone Isn’t Enough

You might think barcode scanning or computer alerts would solve this. They help-but they’re not foolproof.

Barcode scanning prevents 89% of errors when used correctly. But it requires training, working scanners, and staff who don’t bypass the system because it’s “too slow.” One nurse in Birmingham told me she once scanned the wrong vial because the barcode was smudged-and the system didn’t flag it.

Computer alerts? They’re loud. Too loud. Clinicians override nearly half of all LASA alerts because they get flooded with them. If every alert is about a low-risk pair, people stop paying attention. The fix? Only trigger alerts for the FDA’s top 35 high-risk pairs.

And don’t forget handwritten prescriptions. In 2023, 41% of LASA errors still came from doctors scribbling names by hand. No tall man lettering there. No barcode. Just a messy “C” that could be a “D.” That’s why many hospitals now require electronic prescribing for high-risk drugs.

What’s Being Done to Fix This?

There’s real progress. The FDA added 12 new drug pairs to its tall man lettering list in September 2023. That brings the total to 35. By December 2024, all U.S. healthcare systems must use these standardized formats.

Hospitals like Johns Hopkins cut LASA errors by 67% in two years by combining:

• Tall man lettering on all screens and labels
• Forcing staff to write the treatment purpose on every order
• Setting up alerts only for the most dangerous pairs

Even the way drugs are named now has changed. Since 2018, every new drug application must pass a computer analysis using two tools: BI-SIM (for visual similarity) and ALINE (for sound similarity). These tools are 92% accurate at predicting confusion-far better than older methods. Between 2018 and 2023, 17 drug names were blocked from entering the market because they were too likely to be confused.

And now, AI is stepping in. Google Health’s Med-PaLM 2 can predict which drug names might be mixed up with 89% accuracy. It’s not replacing humans-but it’s helping designers build safer systems.

What You Can Do Right Now

You don’t need a hospital system upgrade to protect yourself or someone you care for. Here’s what you can do today:

• Ask for the generic name. If your doctor says “I’m prescribing Valtrex,” ask, “Is that valacyclovir?” Write it down.
• Check the label before taking any pill. Compare it to the prescription slip. If the name looks too similar to another drug you take, pause.
• Use a pill organizer with labels. Don’t rely on color or shape. Write the full name and purpose on each compartment.
• Speak up. If you see a label without tall man letters, or if the name looks confusing, say something. Pharmacists and nurses want to hear it.

One pharmacist in Leeds told me she started asking patients, “Have you ever taken this before?” and “What’s this for?” after a near-miss with clonidine and clonazepam. She hasn’t had another error since.

Final Thought: Safety Is a Habit, Not a Feature

Tall man lettering, barcodes, and alerts are tools. But they only work if people use them right. The biggest danger isn’t bad design-it’s complacency. When you think, “It’s probably fine,” or “I’ve seen this before,” that’s when mistakes happen.

Medication safety isn’t about having the latest tech. It’s about slowing down, reading carefully, and trusting your gut when something looks off. Because in healthcare, a single letter can change everything.