madebykamal

Tall man lettering: what it is, the FDA and ISMP lists, and examples

Updated October 15, 2026 by madebykamal

Tall man lettering writes part of a drug name in capitals to show where two look-alike names differ, as in hydrALAZINE and hydrOXYzine or DOBUTamine and DOPamine. In the US the two main lists are the FDA's list of established names recommended to use tall man letters, begun in 2001, and a longer ISMP list that is voluntary and not approved by the FDA. Studies disagree on how much it reduces errors, and ISMP recommends it as one safeguard among several.

General information, not medical advice. How these guides are made.

What tall man lettering is, and why it exists

Some drug names look so alike that one gets read or picked in place of the other, and the FDA reviews reports of these wrong drug errors. Tall man lettering uses uppercase letters to help tell the names apart. Starting from the left of the name, it capitalizes the letters that differ, so vincristine and vinblastine become vinCRIStine and vinBLAStine.

The FDA notes that the capitals can be combined with color or bolding to flag the difference. ISMP's lists print them in bold.

Examples from the FDA list

These pairs and groups are on the FDA List of Established Drug Names Recommended to Use Tall Man Lettering, written the way the FDA recommends:

ChartKey app icon

ChartKey: Medical Keyboard

Keyboard for medical charting

Get it on the App StoreAbout the app
QR code for ChartKey: Medical Keyboard on the App StoreOn a computer? Scan this with your iPhone camera to open it in the App Store.

Examples from the ISMP list

ISMP's list adds names the FDA list does not cover, including brand names. Some brand names put tall man letters at the start and may not be recognized as brands, so ISMP marks every brand name with an asterisk. Examples:

The FDA list versus the ISMP list

ISMP publishes the two lists in one document; the current edition is cited as 2023 and is offered on ECRI's ISMP pages. According to ISMP, the Joint Commission recommends tall man letters but does not require them. The lists differ in who decides:

How the capital letters are chosen

ISMP follows a tested method called the CD3 rule where it can. Working from the left, capitalize every character once two or more letters differ. Then, working from the right, return two or more shared letters to lowercase. If the names share no letters at the right end, capitalize only the middle, and if the result still looks too alike, choose another option.

There is no single standard for which letters to raise, so ISMP asks organizations to use the published lettering rather than invent their own. In a 2008 ISMP survey, fewer than half of respondents found clonazePAM and LORazePAM effective; ISMP noted that capitalizing PAM in both names could add to their sameness.

Where tall man letters are used

The FDA asks manufacturers to use the letters on product labels. In ISMP's 2008 survey, about half of respondents used them on pharmacy labels, shelf labels, computer screens or medication administration records.

Does tall man lettering reduce errors?

The evidence is mixed. ISMP's summary says many studies from 2000 to 2016 found that tall man letters made similar names easier to read accurately, while some suggested the strategy is ineffective, a gap it puts down largely to study methods and their limitations.

Typing look-alike drug names with ChartKey

If you write notes on an iPhone or iPad, ChartKey is a medical charting keyboard whose Tall Man lettering keeps look-alike drug names apart, and its drug list opens from the keyboard without leaving the note. Its autocorrect knows 703 drug names. ChartKey is a typing tool, not a clinical reference, so confirm clinical content against your institution's approved sources.

Questions people ask

Is tall man lettering used for all medications?

No. It is meant for drug names that have been confused with a similar name, such as those on the FDA and ISMP lists. ISMP keeps its list short so the capitals do not lose their effect.

Is tall man lettering required?

Generally no. The FDA asks manufacturers to adopt it voluntarily, ISMP's list is for voluntary use, and the Joint Commission recommends but does not require it. Your organization's policy may set its own rules.

How do you read a tall man drug name?

Read it as the ordinary drug name. hydrALAZINE is hydralazine and hydrOXYzine is hydroxyzine; the capitals only point to the parts that tell them apart.

Related

Sources