Tall Man Lettering: What It Is and the Full FDA List
Updated
Tall man lettering uses capital letters to make look-alike drug names look less alike. Instead of printing vinblastine and vincristine, which differ by four letters buried in the middle, the label reads vinBLAStine and vinCRIStine. Two drugs that a tired eye can swap at 6pm on a Friday become two drugs that look different at a glance.
It sits squarely in the Patient Safety and Quality Assurance domain, which is 23.75% of the 2026 PTCE, alongside look-alike sound-alike drugs and error-prone abbreviations. This reference is one stop on our PTCB study guide.
What the exam wants you to know
Three things. First, the mechanism: capitals mark the letters that differ, read from the left, so the shared stem stays lowercase. Second, the purpose: it is a defence against wrong-drug errors between look-alike names, and it is voluntary rather than a legal requirement. Third, the source distinction that trips people up: FDA maintains a short list of established (generic) names it has asked manufacturers to relabel, while ISMP maintains a much longer list that includes brand names. Both appear in one ISMP document, so a question asking which body maintains a given pair is really asking whether you noticed there are two lists.
How it works
Tall man lettering highlights the dissimilarities between similar drug names by capitalising the dissimilar letters, starting from the left side of the name. The shared opening stays lowercase, so your eye is pulled to the point where the two names part company:
- chlorproMAZINE and chlorproPAMIDEshare "chlorpro", then diverge. One is an antipsychotic, the other an oral antidiabetic.
- DOBUTamine and DOPamine diverge almost immediately, so the capitals start early.
- predniSONE and prednisoLONE differ only at the tail, which is exactly why the tail is capitalised.
FDA notes it can be combined with colour or bolding to draw further attention and to alert staff that the name is confusable at all.
The FDA list of established drug names
This is the official list from the FDA Name Differentiation Project: established names where FDA has evaluated reports of confusion and asked manufacturers to adopt tall man lettering. It is the shorter and more authoritative of the two lists, and the one to memorise first.
| Names with tall man letters | Note |
|---|---|
| acetoHEXAMIDE · acetaZOLAMIDE | |
| buPROPion · busPIRone | |
| chlorproMAZINE · chlorproPAMIDE | |
| CISplatin · CARBOplatin | |
| clomiPHENE · clomiPRAMINE | |
| cycloSPORINE · cycloSERINE | |
| DAUNOrubicin · DOXOrubicin | |
| dimenhyDRINATE · diphenhydrAMINE | |
| DOBUTamine · DOPamine | |
| glipiZIDE · glyBURIDE | |
| hydrALAZINE · hydrOXYzine | |
| HYDROmorphone | Listed on its own by FDA. |
| medroxyPROGESTERone · methylPREDNISolone · methylTESTOSTERone | A trio, not a pair. |
| migALAstat · migLUstat | |
| mitoXANTRONE | Listed on its own by FDA. |
| niCARdipine · NIFEdipine | |
| predniSONE · prednisoLONE | |
| risperiDONE · rOPINIRole | |
| sulfADIAZINE · sulfiSOXAZOLE | |
| TOLAZamide · TOLBUTamide | |
| traZODone · traMADol | |
| vinBLAStine · vinCRIStine |
Capitalisation above is reproduced exactly as FDA publishes it. A few are not what you would guess: FDA writes predniSONE rather than prednisONE, vinBLAStine rather than vinBLASTine, and diphenhydrAMINEwith a lowercase "r".
FDA list versus ISMP list
These are two different lists that travel together in one PDF, which is the source of most confusion about them.
| List | What it covers | Status |
|---|---|---|
| FDA | Established (generic) names only, where FDA reviewed postmarketing confusion reports and requested a labelling change. The list on this page. | FDA asks manufacturers to comply voluntarily |
| ISMP | A longer additional list, maintained since 2008, adding many more generic pairs plus brand names (for example CeleBREX and CeleXA, LaMICtal and LamISIL). | Recommendation from a safety organisation |
Where it fits with the rest of patient safety
Tall man lettering is one of three related defences the exam groups together, and it helps to know which problem each one solves:
- Tall man lettering attacks names that look alike in print.
- Look-alike sound-alike (LASA) protocols attack names that are confused in speech or on handwritten orders, using separated shelf storage and read-backs. Drill these with the look-alike sound-alike practice questions.
- Error-prone abbreviations attack ambiguous shorthand rather than names, which is the Do Not Use list. See the pharmacy abbreviations reference.
Frequently asked questions
What is tall man lettering?
Tall man lettering, also called mixed case lettering, is a technique that uses uppercase letters to highlight the differences between look-alike drug names. Starting from the left of the name, the letters that differ are capitalised, as in vinBLAStine versus vinCRIStine. It can be combined with bolding or colour to draw further attention to the difference.
Why was tall man lettering introduced?
Because names that look alike get dispensed in place of one another. FDA started the name differentiation project in 2001 to review postmarketing reports of name pair confusion and decide where tall man lettering would reduce wrong-drug errors. Where FDA concludes it helps, it asks the manufacturer to voluntarily revise the labels and labelling.
Is the FDA list the same as the ISMP list?
No, and the distinction matters on the exam. The FDA list covers established (generic) names where FDA has requested a labelling change. ISMP maintains a longer separate list that adds many more pairs, including brand names such as CeleBREX and CeleXA, based on error reports it collects. The two are published side by side in one ISMP document, which is why they are often confused.
Which letters get capitalised?
The dissimilar ones, working from the left of the name. The shared beginning stays lowercase and the part that distinguishes the drug is capitalised, which is why chlorproMAZINE and chlorproPAMIDE share nine lowercase letters before the capitals begin.
Is tall man lettering required by law?
No. FDA requests that manufacturers voluntarily revise labels, and ISMP recommends the practice. It is a safety convention rather than a regulation, though many hospitals and pharmacy systems mandate it internally and it is expected knowledge for the PTCE patient safety domain.
Keep studying
Name-confusion questions are among the most predictable on the exam, because the pairs come from a fixed list. Test yourself with the PTCB patient safety quiz and the high-alert medications practice set, then read the full Patient Safety domain guide.
Official sources checked
- FDA Name Differentiation Project: List of Established Drug Names Recommended to Use Tall Man Lettering
- ISMP: Special edition on tall man lettering and the updated ISMP list
PTCB Quiz Prep is an independent study resource, not affiliated with the Pharmacy Technician Certification Board. This page is exam reference framing, not medical advice. See our editorial standards.