Look-alike and sound-alike drug names, and how FDA tries to keep them apart

In January 2021, a repackager began a recall after finding that a bottle labeled benzonatate 100 mg capsules, a cough medicine, held benzphetamine 50 mg tablets, a weight-loss drug, and that a bottle labeled benzphetamine held the benzonatate. FDA classed the benzonatate side of the swap Class I, its most serious category, according to the agency's enforcement record¹. The record does not say how the swap happened. The two names share their first four letters.

Drug names that look or sound alike are one of the oldest known sources of medication error. A 1999 study in the journal Medical Care began from the estimate that "one of every four medication errors reported in the United States is a name-confusion error," its abstract says². That same year, an Institute of Medicine report put deaths from medication errors of all kinds at an estimated 7,000 a year in the United States, a figure FDA still cites in its 2020 guidance on proprietary names³.

How FDA screens a proposed name

Inside FDA's drug center, the Division of Medication Error Prevention and Analysis "reviews and determines the acceptability of proposed proprietary names to minimize medication errors associated with product name confusion," according to FDA's medication errors page⁴. The same office reviews container labels, cartons and packaging. After approval it monitors error reports, which reach FDA through a reporting system that is voluntary for health professionals and patients.

The legal hook is a labeling regulation. A drug's labeling can be considered misleading if it uses "a proprietary name that, because of similarity in spelling or pronunciation, may be confused with the proprietary name or the established name of a different drug or ingredient," under 21 CFR 201.10(c)(5)⁵.

FDA screens candidate names with software it built, the Phonetic and Orthographic Computer Analysis tool, known as POCA. A proposed name is run against drug reference databases such as Drugs@FDA and RxNorm, and each match gets a combined similarity score for spelling and sound. The 2020 guidance sets out the bands.

Source: FDA, Best Practices in Developing Proprietary Names for Human Prescription Drug Products (December 2020).

FDA says the 55 percent threshold rests on validation work on the POCA algorithms and that "the combined measure of similarity has been positively correlated to errors involving name confusion." That idea traces to the 1999 Medical Care study, which compared 1,127 name pairs from published error reports and national error databases with 1,127 control pairs. Every measure of similarity proved to be a significant risk factor, and a three-measure model sorted cases from controls with cross-validated accuracy of 94.8 percent, the authors reported².

Review runs on a clock set in user-fee agreements. FDA's goal is to give a tentative answer on a complete name submission within 180 days during the investigational stage and within 90 days when the name comes with a new drug or biologics application, according to FDA's 2016 guidance on proprietary name submissions⁶. A rejected name starts a new clock for the alternate.

Why generic names can look alike on purpose

Most generic drugs are sold under their established, nonproprietary name, the one that appears in the Orange Book and on the bottle. Those names come from the United States Adopted Names Council, which builds them from shared word parts called stems. USAN stems "are intended to indicate a pharmacological or chemical trait," FDA's 2020 guidance explains. Two drugs from the same class will often end the same way.

That system helps a prescriber place an unfamiliar drug, and it also produces pairs that differ by a syllable. POCA screening applies to proprietary names. Established names that turn out to be confusable after they are on the market are handled another way.

How tall man lettering works

FDA's answer for confusable established names is typographic. Tall man lettering "uses uppercase lettering to help differentiate look-alike drug names" by capitalizing the letters that differ, as in vinBLAStine and vinCRIStine, according to FDA's Name Differentiation Project page⁷. FDA began the project in 2001 to evaluate postmarketing reports of name pair confusion. When it decides tall man lettering fits, FDA "will request the manufacturer voluntarily revise their labels and labeling," then adds the names to its list.

The list, on a page FDA marks as current as of June 12, 2026, has 23 entries covering 43 established names. Several involve drugs GxRadar tracks.

Source: FDA List of Established Drug Names Recommended to Use Tall Man Lettering, content current as of June 12, 2026. Uses summarized by GxRadar.

GxRadar's drug pages for glipizide, trazodone and prednisone show each drug's price history and recall record. FDA's page cites a 2016 special edition on tall man lettering from the Institute for Safe Medication Practices, which keeps its own list.

FDA does not treat capital letters as a cure. Its 2022 labeling guidance says that "despite the use of tall man lettering, sometimes the dissimilar letters can still be overlooked," and suggests adding larger type, bold or color where that is not enough, according to the document⁸. The same guidance cites a 2006 Institute of Medicine report that blamed labeling and packaging issues for 33 percent of medication errors and 30 percent of fatalities from medication errors reported to the Institute for Safe Medication Practices.

Mix-ups at the packaging line

Name confusion at a prescriber's desk or a pharmacy counter leaves few public traces. Mix-ups at a factory or repackager do, because they lead to recalls. GxRadar searched the reason-for-recall text of 18,076 drug recall records in FDA's openFDA enforcement data¹, 2012 through Oct. 28, 2026, for mentions of a label mix-up.

Source: GxRadar analysis of openFDA drug enforcement records through Oct. 28, 2026. Each record is one product line.

Outside the 2014 burst, label mix-ups ran at between eight and 18 records a year from 2017 through 2025. Some involve drugs that look nothing alike in the bottle. In August 2025, a company began a Class I recall of 230 bottles of yellow meloxicam 7.5 mg tablets that had been labeled as blue cyclobenzaprine 10 mg tablets, FDA's record shows¹. FDA's packaging rules require written procedures to prevent "mixups and cross-contamination by physical or spatial separation from operations on other drug products," under 21 CFR 211.130⁹. Our explainers on how drug recalls work and why a pill can change color cover what a patient sees from the outside.

A pill that looks different from the last refill, or a label name that seems unfamiliar, is a reasonable thing to raise with the pharmacist before leaving the counter; our guide to reading a prescription label shows where the drug name and description appear. FDA's error reporting system takes reports from patients as well as professionals, and the agency says a report can lead it to revise labeling, issue a safety communication or, in some cases, consider a change to a product's name.