Look-Alike, Sound-Alike Medications: Examples, List, and How to Prevent Errors

Hydroxyzine treats itching and anxiety. Hydralazine lowers blood pressure. A few letters apart on a label, a screen, or a rushed phone order, they’re easy to confuse, and they’re far from the only pair. Look-alike, sound-alike medications are one of the most persistent sources of preventable medication errors, and confusion between LASA drug names has been estimated to account for up to one in four medication errors.

This guide explains what LASA medications are, lists common examples, and covers the practical steps healthcare teams use to prevent mix-ups.

Drugs with similar names, spelling, or packaging that are easily confused, leading to errors.

Look-alike, sound-alike (LASA) medications are drugs whose names look similar when written or typed, sound similar when spoken, or come in packaging that looks alike. Confusion can happen between two brand names, two generic names, or a brand and a generic name.

The Institute for Safe Medication Practices (ISMP) maintains the most widely used List of Confused Drug Names, built from errors reported to its national reporting programs.

A mix-up can give a patient the wrong drug or dose, and some confusions can cause serious harm.

When two drugs are confused, the patient misses the medication they need and receives one they don’t. The consequences depend on the drugs involved. Some mix-ups cause little harm; others can be fatal. Published case reports include a patient given hydromorphone instead of morphine who suffered a fatal respiratory arrest after discharge. Hydromorphone is much more potent than morphine, so the same dose is not interchangeable.

Common pairs include hydroxyzine and hydralazine, and Celebrex, Celexa, and Cerebyx.

The examples below all appear on the ISMP List of Confused Drug Names. Tall man letters (the capitalized parts) are shown where ISMP or the FDA recommends them.

ISMP’s full list includes hundreds of name pairs and is updated regularly. Use it, not this table, as your reference in practice.

Which LASA drugs are high-alert medications?

High-alert drugs like insulins, opioids, and some chemotherapy agents, where a mix-up can be severe.

Several LASA pairs involve high-alert medications, drugs that carry a heightened risk of significant harm when used in error. Insulins (HumaLOG and HumuLIN), opioids (HYDROcodone and oxyCODONE; hydromorphone and morphine), and chemotherapy (CISplatin and CARBOplatin) all appear on the confused-names list. These pairs deserve the strongest safeguards.

Similar names and packaging, plus handwriting, verbal orders, and rushed or interrupted workflows.

LASA errors rarely come from the name alone. Common contributing factors include:

• Similar spelling or sound, especially in shared prefixes or suffixes
• Look-alike packaging, like similar colors, shapes, or labels
• Handwritten orders that are hard to read
• Verbal and phone orders, where similar-sounding names are easy to mishear
• Auto-complete and drop-down menus that place similar names side by side
• Unfamiliar drug names, such as a newly marketed drug or one outside a clinician’s specialty
• Interruptions, fatigue, and time pressure

Related: Medical Terminology Miscommunication: Causes, Examples, and How to Prevent It

Capitalizing the letters that differ in similar drug names, like hydrOXYzine and hydrALAZINE.

Tall man lettering uses selective capitalization to draw the eye to the part of a name that’s different. The FDA began recommending it in 2001 through its Name Differentiation Project, asking manufacturers of certain look-alike generic drugs to use it on labels. ISMP has since published an additional list of recommended tall man names.

Use tall man lettering, separate storage, barcode scanning, indications on orders, and read-back.

No single safeguard is enough. The strongest approach layers several of them.

How does tall man lettering help?

Highlighting the letters that differ on labels and screens makes similar names easier to tell apart.

Apply tall man lettering consistently across shelf labels, automated dispensing cabinets, pharmacy systems, and electronic health records, so the same name looks the same everywhere.

Why store LASA drugs separately?

Keeping LASA drugs apart, or flagged with alert labels, stops the wrong one being picked by habit.

Don’t shelve confusable drugs side by side or in alphabetical order next to each other. Use separate locations, auxiliary warning labels, or bin alerts for known pairs.

Why include the indication on prescriptions?

Writing what the drug is for helps pharmacists and nurses catch a name that doesn’t fit the purpose.

The World Health Organization recommends including the indication on orders. “HydrOXYzine for itching” is much harder to confuse with hydrALAZINE than “hydroxyzine 25 mg” alone. Including both the brand and generic name adds another check.

Why read back verbal orders?

Repeating and spelling the drug name catches sound-alike mix-ups before the drug is given.

For verbal and phone orders, the receiver repeats the order back, spells the drug name when needed, and confirms the dose and indication. This is closed-loop communication applied to medication safety. Learn more about closed-loop communication in healthcare.

How does barcode scanning prevent LASA errors?

Scanning the barcode checks the right drug for the right patient before it’s given.

Barcode medication administration compares the scanned product against the patient’s active order, so a look-alike product picked by mistake triggers an alert at the bedside.

What should you do when a drug name is unfamiliar?

Check an unfamiliar or similar-sounding drug name in a trusted reference before acting on it.

If a drug name is new to you, or close to one you know, stop and verify it in your drug formulary or reference, or call the pharmacist or prescriber, before preparing or giving the drug. For unfamiliar clinical terms in an order or note, a quick reference such as HosTalky’s Meditionary lets you check the meaning in seconds, without leaving the app.

Both publish confused drug name lists and urge tall man lettering, clear labels, and staff training.

• ISMP publishes the List of Confused Drug Names and a list of recommended tall man letters, and encourages organizations to identify the LASA drugs they actually stock and use.
• The World Health Organization made look-alike, sound-alike medication names the first of its Patient Safety Solutions in 2007. Its recommendations include tall man lettering, including both brand and generic names and the indication on orders, read-back of verbal orders, and education for staff and patients.
• The FDA reviews proposed drug names before approval to reduce confusion, and some marketed names have been changed after reported mix-ups.