How to Identify Look-Alike Names on Prescription Labels

Every year, thousands of patients in the UK and US are put at risk not because of wrong dosages or allergic reactions, but because two drug names look too similar on a label. Look-alike drug names-like hydroCODONE and hydroHYDRAZINE, or doXEPamine and doBUTamine-cause mix-ups that lead to overdoses, missed treatments, and even deaths. The problem isn’t rare. About 1 in 4 medication errors comes from names that are visually or phonetically confusing. And it’s not just a pharmacy issue-it happens in hospitals, clinics, and even at home when patients misread their own labels.

What Makes Drug Names Look-Alike?

Look-alike and sound-alike (LASA) names aren’t random. They follow patterns. Most share 60-80% of the same letters. For example, Hydralazine and Hydroxyzine differ by just two letters, but one treats high blood pressure, and the other is an antihistamine. Mix them up, and you could cause dangerous drops in blood pressure-or a patient might get sedated when they need a vasodilator.

The U.S. Food and Drug Administration (FDA) and the Institute for Safe Medication Practices (ISMP) have identified over 3,000 such pairs. These aren’t just theoretical risks. Studies show that 1.7 errors occur per 1,000 prescriptions because of these names. And 34% of those errors actually reach the patient. Seven percent cause harm.

The biggest culprits? High-alert medications-insulin, opioids, anticoagulants, and chemotherapy drugs. One pharmacist in Birmingham told me, “I once saw a nurse grab Humalog instead of Humulin. The patient was due for long-acting insulin. We caught it before the injection, but only because the label had tall man letters.”

Tall Man Lettering: The Visual Fix

The most widely used tool to fight this is called tall man lettering. It’s simple: capitalize the parts of the drug name that are different. So instead of “hydroxyzine,” it’s written as “hydrOXYzine.” For “hydralazine,” it’s “hydrALazine.” The capital letters jump out, making it harder to confuse the two.

The FDA has officially recommended tall man lettering for 35 drug pairs as of 2024. These include:

• vinBLAstine vs. vinCRIStine
• CISplatin vs. CARboplatin
• doXEpamine vs. doBUTamine
• hydrOXYzine vs. hydrALazine

Research shows tall man lettering reduces visual confusion by 32%. That’s good-but not enough on its own. When combined with color coding or purpose-of-treatment notes (like “for anxiety” or “for high BP”), effectiveness jumps to 59%.

Where Do Errors Still Happen?

Even with tall man lettering, mistakes happen. Why? Because the system isn’t consistent.

- Electronic Health Records (EHRs): Some systems show tall man letters, others don’t. Nurses switching between screens get confused. One ICU nurse said, “The EHR has it right, but the MAR doesn’t. I end up guessing.”

- Handwritten prescriptions: If a doctor scribbles “Hydroxyzine” without capitalization, the pharmacist has to guess. In 2023, 41% of LASA errors traced back to handwriting.

- Printed labels: Low-quality printers, faded ink, or small fonts make tall man letters unreadable. The Joint Commission requires at least 12-point font and a 4.5:1 contrast ratio between text and background. Many community pharmacies still fall short.

- Automated dispensing cabinets: If two similar drugs appear next to each other in a dropdown menu, users pick the wrong one. The FDA now requires EHRs to prevent consecutive display of LASA pairs. Hospitals that followed this saw a 41% drop in selection errors.

How to Spot a Look-Alike Name-A 3-Step Check

You don’t need fancy tech to catch these errors. Here’s what every healthcare worker should do:

1. Read the full label-not just the first few letters. Don’t assume. Look at the entire name, including the manufacturer and strength.
2. Confirm with a second person-especially for high-risk drugs like insulin or morphine. A second set of eyes catches 68% of errors missed by one person.
3. Read it again when handing it off-whether to a nurse, patient, or another department. This final check reduces errors by 52%.

This isn’t bureaucracy. It’s survival. At Johns Hopkins Hospital, this exact process cut LASA errors by 67% over two years.

Technology That Helps-And What Doesn’t

Barcodes and alerts sound like perfect solutions. And they are-when used right.

- Barcode scanning prevents 89% of errors at the point of dispensing and administration. But it costs hospitals around $153,000 to implement. Smaller clinics can’t always afford it.

- Computer alerts warn you when you select a LASA pair. But 49% of clinicians ignore them because they get too many false alarms. The fix? Only trigger alerts for the FDA’s top 35 high-risk pairs. That cuts alert fatigue by more than half.

- AI tools like Google’s Med-PaLM 2 can predict confusing names with 89% accuracy. The FDA already uses AI to screen new drug names before approval. Since 2018, 17 potentially dangerous names were blocked from entering the market because of this.

But here’s the catch: technology can’t replace human vigilance. A 2021 study found that even when tall man letters were present, errors still happened because staff were rushed, distracted, or overworked.

What Patients Can Do

You don’t have to be a pharmacist to protect yourself. If you’re handed a new prescription:

• Ask: “Is this the right medicine for my condition?”
• Check the label: Are any letters capitalized? If not, ask why.
• Compare the name to your last prescription. Did it change?
• Use a phone app like Medisafe or MyTherapy to log your meds and flag confusing names.

One patient in Birmingham noticed her “Hydroxyzine” label had no tall man letters. She asked her pharmacist, who admitted the printer was broken. They printed a new one with correct formatting. That simple question prevented a potential overdose.

The Bigger Picture: Why This Matters

This isn’t just about labels. It’s about system design. The FDA, ISMP, and Joint Commission agree: tall man lettering is necessary-but not sufficient. Real safety comes from combining tools:

- Tall man lettering on all labels and screens - Color coding for high-alert drugs - Purpose-of-treatment notes on every prescription - Barcode scanning at every critical point - Staff training that includes real-world case studies Hospitals that use all these together reduce LASA errors by up to 70%. Those that rely only on tall man letters? They’re still at risk.

The good news? Change is happening. In January 2023, the National Council for Prescription Drug Programs released Version 3.0 of its LASA Data Standard, allowing real-time alerts across pharmacy, EHR, and supply chain systems. By 2026, the ISMP plans to make tall man lettering mandatory across all U.S. healthcare settings.

But until then, vigilance is your best defense.

What You Should Do Today

If you’re a pharmacist, nurse, doctor, or even a patient:

• Learn the top 10 LASA pairs used in your facility.
• Check your EHR or label printer: Are tall man letters enabled?
• Ask your pharmacy: Do they use color coding or purpose-of-treatment notes?
• Never assume. Always read the full name.
• If you see a missing tall man letter-report it. It’s not a small thing. It’s a safety gap.

Medication errors aren’t inevitable. They’re preventable. And it starts with noticing the difference between two letters.