Look-Alike, Sound-Alike Medication Names That Cause Errors: What You Need to Know

Every year, thousands of people in the UK and around the world are harmed-not by the medicine they need, but by the medicine they get by mistake. It’s not a glitch in the system. It’s not a lazy pharmacist. It’s often something as simple as two drug names that look too similar or sound too much alike. These are called look-alike, sound-alike (LASA) medications, and they’re one of the most dangerous, yet preventable, causes of medication errors in hospitals, pharmacies, and even GP surgeries.

What Exactly Are LASA Medications?

LASA stands for look-alike, sound-alike. It’s when two or more drugs have names that are visually or phonetically similar, making them easy to mix up. Think of HYDROmorphone and hYDROcodone. Both are painkillers. Both start with “hydro.” Both are written in similar fonts on labels. But one is ten times stronger than the other. Give the wrong one to the wrong patient, and you could cause a fatal overdose.

It’s not just about spelling. It’s also about how they sound. A nurse hears “celexa” over the phone and writes down “celiac.” A doctor says “propranolol” quickly, and the pharmacist hears “propanolol.” These aren’t typos. These are real, life-threatening mix-ups that happen more often than you think.

According to the World Health Organization, about one in four medication errors in the US is caused by drug name confusion. In UK hospitals, the numbers are just as alarming. A 2022 study found that 64% of LASA errors came from drug names alone-no packaging, no pills, just the name.

High-Risk Pairs You Should Know

Some drug pairs are notorious. They show up on safety lists year after year. Here are a few that still cause confusion today:

• Simvastatin 10 mg and Simvastatin 20 mg - Even the same drug, different strengths, can be confused if labels are faded or stacked together.
• Doxorubicin and Daunorubicin - Both are chemotherapy drugs. Mix them up, and you could give a patient a dose that’s too toxic-or too weak to work.
• Levothyroxine and Synthroid - One’s the generic, one’s the brand. But they’re the same drug. Still, if a nurse thinks they’re different, they might give the wrong dose or skip one entirely.
• Vecuronium and Versed - One paralyzes muscles. The other calms anxiety. Give the wrong one in the ICU, and a patient could stop breathing.
• Naltrexone and Naloxone - Both treat opioid issues. But naloxone reverses overdoses. Naltrexone blocks them long-term. Confusing them could mean a patient doesn’t get help in time.

These aren’t hypotheticals. The FDA’s MAUDE database recorded at least 128 deaths between 2018 and 2022 linked directly to LASA errors. Most of them were preventable.

Why Do These Mistakes Keep Happening?

You’d think after 20 years of warnings, hospitals would have this figured out. But the truth is, it’s not that simple.

First, humans are bad at noticing small differences. When you’re tired, rushed, or working a double shift, your brain starts taking shortcuts. You see “metoprolol” and think “metformin.” You hear “epinephrine” and write “epinephrine.” You don’t even realize you made a mistake until it’s too late.

Second, packaging doesn’t help. Two drugs can have the same color pill, same bottle shape, same label font. Even the font size on the strength can be identical. One study found that 25% of LASA errors came from packaging that looked too similar-not the name at all.

Third, technology isn’t always the fix. Tall man lettering-where you capitalize parts of the name to make them stand out, like HYDROmorphone and hYDROcodone-was supposed to help. And it does, sometimes. But if staff don’t know why it’s there, or if the system doesn’t highlight it clearly, it’s just decoration. One review found it only reduced errors by a few percentage points-and only if people were trained to use it properly.

And let’s not forget the human factor. In a busy pharmacy, a technician grabs the first bottle that looks right. In a rush, a doctor says “give her the thyroid med.” No name, no strength, no route. Just “thyroid med.” That’s how you get levothyroxine instead of Synthroid-or worse, the wrong dose.

What’s Being Done to Stop It?

There are real solutions. But they require effort, money, and consistency.

Tall man lettering is still used in the UK and US, and it’s required for high-risk drugs. But it’s not universal. Not all EHR systems enforce it. Not all printed labels use it. And many older drugs still have confusing names because they were approved before these rules existed.

Electronic prescribing systems like Epic and Cerner now have built-in LASA alerts. If you type in “clonidine,” the system might pop up: “Did you mean clonazepam?” That’s good. But it’s not perfect. If the alert is too loud, staff turn it off. If it’s too slow, they ignore it. The best systems learn from past errors and adapt.

Standardized packaging is slowly improving. The UK’s Medicines and Healthcare products Regulatory Agency (MHRA) now encourages manufacturers to use different colors, shapes, and label layouts for similar drugs. But it’s voluntary. Not all companies follow it.

Training is key. Nurses and pharmacists in oncology, ICU, and geriatrics get extra training every quarter. They learn the top 20 LASA pairs used in their unit. They practice catching errors before they happen. But in smaller clinics or care homes? Training is often minimal-or nonexistent.

What Can You Do?

You don’t have to be a doctor to help prevent these errors.

• Know your meds. If you’re taking simvastatin, know the strength. If you’re on levothyroxine, know the brand. Don’t assume they’re interchangeable.
• Ask questions. “Is this the same as what I had last month?” “Why is this pill a different color?” “Is this the one that starts with ‘H’ or ‘C’?”
• Check the label. Don’t just take the bottle. Look at the name, the strength, the number of pills. Compare it to your prescription.
• Speak up. If a nurse hands you a pill that looks different, say something. If a pharmacist says “it’s the same,” ask for proof.

Patients are the last line of defense. And too often, they’re the only one who notices something’s wrong.

The Bigger Picture

This isn’t just about one bad drug name. It’s about a system that still lets dangerous names get approved. In 2022, the FDA rejected 34 new drug names because they were too similar to existing ones. That’s progress. But it’s not enough. There are still hundreds of risky pairs on the market.

The WHO and ISMP are pushing for global standards: no new drug should get a name that could be confused with another. They want mandatory testing before approval. They want packaging rules. They want AI systems that flag risky names before they’re even manufactured.

In the meantime, we’re stuck with what we have. And that means every pharmacist, nurse, doctor, and patient needs to be alert.

Future Solutions on the Horizon

New tech is coming. At Johns Hopkins, researchers are testing AI voice recognition that listens to doctors giving verbal orders. If someone says “give him the insulin,” and the system hears “heparin,” it interrupts. Early results show it catches 89% of risky mix-ups.

Some hospitals are using color-coded wristbands for high-risk drugs. Others are putting QR codes on labels that link to a safety alert when scanned.

But the most powerful tool? Awareness. The more people know about LASA errors, the more likely they are to catch them.

Final Thought

Medicines are meant to heal. But when names look too similar or sound too close, they can hurt. These errors aren’t rare. They’re systemic. And they’re preventable-if we stop treating them as accidents and start treating them as design failures.

The next time you pick up a prescription, take a second. Read the name. Check the strength. Ask if it’s right. You might just save a life.