ISMP List of Look-Alike Drug Names with Recommended Tall Man (Mixed Case) Letters contains drug name pairs or larger groupings with recommended, bolded uppercase letters to help draw attention to the dissimilarities in look-alike drug names. The list includes mostly generic-generic drug names, although a few brand-brand or brand-generic names are included. The US Food and Drug Administration (FDA) list of drug names with recommended tall man (mixed case) letters was initiated in 2001 with the agency’s Name Differentiation Project.
Table 1 provides an alphabetized list of FDA-approved established drug names with recommended tall man (mixed case) letters.
Table 2 provides an alphabetized list of additional drug names with recommendations from ISMP regarding the use and placement of tall man (mixed case) letters. This is not an official list approved by FDA. It is intended for voluntary use by healthcare practitioners, drug information vendors, and medication technology vendors. Any product label changes by manufacturers require FDA approval.
How to cite: US Food and Drug Administration (FDA) and Institute for Safe Medication Practices (ISMP). FDA and ISMP Lists of Look-Alike Drug Names with Recommended Tall Man Letters. ISMP; 2023.
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| Drug Name With Tall Man Letters | Confused With |
|---|---|
| acetaZOLAMIDE | acetoHEXAMIDE* |
| acetoHEXAMIDE* | acetaZOLAMIDE |
| buPROPion | busPIRone |
| busPIRone | buPROPion |
| CARBOplatin | CISplatin |
| chlorproMAZINE | chlorproPAMIDE |
| chlorproPAMIDE | chlorproMAZINE |
| CISplatin | CARBOplatin |
| clomiPHENE | clomiPRAMINE |
| clomiPRAMINE | clomiPHENE |
| cycloSERINE | cycloSPORINE |
| cycloSPORINE | cycloSERINE |
| DAUNOrubicin | DOXOrubicin |
| dimenhyDRINATE | diphenhydrAMINE |
| diphenhydrAMINE | dimenhyDRINATE |
| DOBUTamine | DOPamine |
| DOPamine | DOBUTamine |
| DOXOrubicin | DAUNOrubicin |
| glipiZIDE | glyBURIDE |
| glyBURIDE | glipiZIDE |
| hydrALAZINE | HYDROmorphone — hydrOXYzine |
| HYDROmorphone | hydrALAZINE — hydrOXYzine |
| hydrOXYzine | hydrALAZINE — HYDROmorphone |
| medroxyPROGESTERone | methylPREDNISolone — methylTESTOSTERone |
| methylPREDNISolone | medroxyPROGESTERone — methylTESTOSTERone |
| methylTESTOSTERone | methylPREDNISolone — medroxyPROGESTERone |
| migALAstat | migLUstat |
| migLUstat | migALAstat |
| mitoXANTRONE | Not specified |
| niCARdipine | NIFEdipine |
| NIFEdipine | niCARdipine |
| prednisoLONE | predniSONE |
| predniSONE | prednisoLONE |
| risperiDONE | rOPINIRole |
| rOPINIRole | risperiDONE |
| sulfADIAZINE | sulfiSOXAZOLE* |
| sulfiSOXAZOLE* | sulfADIAZINE |
| TOLAZamide | TOLBUTamide* |
| TOLBUTamide* | TOLAZamide |
| traMADol | traZODone |
| traZODone | traMADol |
| vinBLAStine | vinCRIStine |
| vinCRIStine | vinBLAStine |
| Drug Name With Tall Man Letters | Confused With |
|---|---|
| ALfentanil | fentaNYL — SUFentanil |
| ALPRAZolam | clonazePAM — LORazepam |
| aMILoride | amLODIPine |
| amLODIPine | aMILoride |
| ARIPiprazole | RABEprazole |
| azaCITIDine | azaTHIOprine |
| azaTHIOprine | azaCITIDine |
| BUPivacaine | ROPivacaine |
| carBAMazepine | OXcarbazepine |
| CARBOplatin† | CISplatin† |
| ceFAZolin | cefoTEtan — cefOXitin — cefTAZidime — cefTRIAXone |
| cefoTEtan | ceFAZolin — cefOXitin — cefTAZidime — cefTRIAXone |
| cefOXitin | ceFAZolin — cefoTEtan — cefTAZidime — cefTRIAXone |
| cefTAZidime | ceFAZolin — cefoTEtan — cefOXitin — cefTRIAXone |
| cefTRIAXone | ceFAZolin — cefoTEtan — cefOXitin — cefTAZidime |
| CeleBREX‡ | CeleXA‡ |
| CeleXA‡ | CeleBREX‡ |
| chlordiazePOXIDE | chlorproMAZINE† |
| chlorproMAZINE† | chlordiazePOXIDE |
| CISplatin† | CARBOplatin† |
| cloBAZam | clonazePAM |
| clonazePAM | ALPRAZolam — cloBAZam — cloNIDine — cloZAPine — LORazepam |
| cloNIDine | clonazePAM — cloZAPine — KlonoPIN‡ |
| cloZAPine | clonazePAM — cloNIDine |
| cycloPHOSphamide | cycloSERINE† — cycloSPORINE† |
| cycloSERINE† | cycloPHOSphamide — cycloSPORINE† |
| cycloSPORINE† | cycloPHOSphamide — cycloSERINE† |
| DACTINomycin | DAPTOmycin |
| DAPTOmycin | DACTINomycin |
| DEPO-Medrol‡ | SOLU-Medrol‡ |
| dexAMETHasone | dexmedeTOMIDine |
| dexmedeTOMIDine | dexAMETHasone |
| diazePAM | dilTIAZem |
| dilTIAZem | diazePAM |
| DOCEtaxel | PACLitaxel |
| DOXOrubicin† | IDArubicin |
| droNABinol | droPERidol |
| droPERidol | droNABinol |
| DULoxetine | FLUoxetine — PARoxetine |
| ePHEDrine | EPINEPHrine |
| EPINEPHrine | ePHEDrine |
| epiRUBicin | eriBULin |
| eriBULin | epiRUBicin |
| fentaNYL | ALfentanil — SUFentanil |
| flavoxATE | fluvoxaMINE |
| FLUoxetine | DULoxetine — PARoxetine |
| fluPHENAZine | fluvoxaMINE |
| fluvoxaMINE | flavoxATE — fluPHENAZine |
| guaiFENesin | guanFACINE |
| guanFACINE | guaiFENesin |
| HumaLOG‡ | HumuLIN‡ |
| HumuLIN‡ | HumaLOG‡ |
| hydrALAZINE† | hydroCHLOROthiazide —hydrOXYzine† |
| hydroCHLOROthiazide | hydrALAZINE† — hydrOXYzine† |
| HYDROcodone | oxyCODONE |
| HYDROmorphone† | morphine — oxyMORphone |
| HYDROXYprogesterone | medroxyPROGESTERone† |
| hydrOXYzine† | hydrALAZINE† — hydroCHLOROthiazide |
| IDArubicin | DOXOrubicin† — idaruCIZUmab |
| idaruCIZUmab | IDArubicin |
| inFLIXimab | riTUXimab |
| ISOtretinoin | tretinoin |
| KlonoPIN‡ | cloNIDine |
| LaMICtal‡ | LamISIL‡ |
| LamISIL‡ | LaMICtal‡ |
| lamiVUDine | lamoTRIgine |
| lamoTRIgine | lamiVUDine |
| levETIRAcetam | levOCARNitine — levoFLOXacin |
| levOCARNitine | levETIRAcetam |
| levoFLOXacin | levETIRAcetam |
| LEVOleucovorin | leucovorin |
| LORazepam | ALPRAZolam — clonazePAM |
| medroxyPROGESTERone† | HYDROXYprogesterone |
| metFORMIN | metroNIDAZOLE |
| methazolAMIDE | methIMAzole — metOLazone |
| methIMAzole | methazolAMIDE — metOLazone |
| metOLazone | methazolAMIDE — methIMAzole |
| metroNIDAZOLE | metFORMIN |
| metyraPONE | metyroSINE |
| metyroSINE | metyraPONE |
| miFEPRIStone | miSOPROStol |
| migALAstat† | migLUstat† |
| migLUstat† | migALAstat† |
| miSOPROStol | miFEPRIStone |
| mitoMYcin | mitoXANTRONE† |
| mitoXANTRONE† | mitoMYcin |
| NexAVAR‡ | NexIUM‡ |
| NexIUM‡ | NexAVAR‡ |
| niCARdipine† | NIFEdipine† — niMODipine |
| NIFEdipine† | niCARdipine† — niMODipine |
| niMODipine | niCARdipine† — NIFEdipine† |
| NovoLIN‡ | NovoLOG‡ |
| NovoLOG‡ | NovoLIN‡ |
| OLANZapine | QUEtiapine |
| OXcarbazepine | carBAMazepine |
| oxyBUTYnin | oxyCODONE — OxyCONTIN‡ — oxyMORphone |
| oxyCODONE | HYDROcodone — oxyBUTYnin — OxyCONTIN‡ — oxyMORphone |
| OxyCONTIN‡ | oxyBUTYnin — oxyCODONE — oxyMORphone |
| oxyMORphone | HYDROmorphone† — oxyBUTYnin — oxyCODONE — OxyCONTIN‡ |
| PACLitaxel | DOCEtaxel |
| PARoxetine | DULoxetine — FLUoxetine |
| PAZOPanib | PONATinib |
| PEMEtrexed | PRALAtrexate |
| penicillAMINE | penicillin |
| PENTobarbital | PHENobarbital |
| PHENobarbital | PENTobarbital |
| PHYSostigmine | pyRIDostigmine |
| PONATinib | PAZOPanib |
| PRALAtrexate | PEMEtrexed |
| PriLOSEC‡ | PROzac‡ |
| PROzac‡ | PriLOSEC‡ |
| pyRIDostigmine | PHYSostigmine |
| QUEtiapine | OLANZapine |
| quiNIDine | quiNINE |
| quiNINE | quiNIDine |
| RABEprazole | ARIPiprazole |
| raNITIdine* | riMANTAdine |
| rifAMPin | rifAXIMin |
| rifAXIMin | rifAMPin |
| riMANTAdine | raNITIdine* |
| RisperDAL‡ | rOPINIRole† |
| risperiDONE† | rOPINIRole† |
| riTUXimab | inFLIXimab |
| romiDEPsin | romiPLOStim |
| romiPLOStim | romiDEPsin |
| rOPINIRole† | RisperDAL‡ — risperiDONE† |
| ROPivacaine | BUPivacaine |
| SandIMMUNE‡ | SandoSTATIN‡ |
| SandoSTATIN‡ | SandIMMUNE‡ |
| sAXagliptin | SITagliptin |
| SITagliptin | sAXagliptin — SUMAtriptan |
| Solu-CORTEF‡ | SOLU-Medrol‡ |
| SOLU-Medrol‡ | DEPO-Medrol‡ — Solu-CORTEF‡ |
| SORAfenib | SUNItinib |
| SUFentanil | ALfentanil — fentaNYL |
| sulfADIAZINE† | sulfaSALAzine |
| sulfaSALAzine | sulfADIAZINE† |
| SUMAtriptan | SITagliptin — ZOLMitriptan |
| SUNItinib | SORAfenib |
| tiaGABine | tiZANidine |
| tiZANidine | tiaGABine |
| traMADol† | traZODone† |
| traZODone† | traMADol† |
| valACYclovir | valGANciclovir |
| valGANciclovir | valACYclovir |
| ZOLMitriptan | SUMAtriptan |
| ZyPREXA‡ | ZyrTEC‡ |
| ZyrTEC‡ | ZyPREXA‡ |
* These drugs have been discontinued and are not marketed in the United States.
† These drug names are also on the FDA list.
‡ Brand names always start with an uppercase letter. Some brand names incorporate tall man letters in initial characters and may not be readily recognized as brand names. A double dagger follows all brand names on the ISMP list.
To promote standardization regarding which letters to present in uppercase/bold, ISMP follows a tested methodology whenever possible called the CD3 rule.19 The methodology suggests working from the left of the drug name first by capitalizing all the characters to the right once 2 or more dissimilar letters are encountered, and then, working from the right, returning 2 or more letters common to both words to lowercase letters. When the rule cannot be applied because there are no common letters on the right side of the name, the methodology suggests capitalizing the central part of the word only. When application of this rule fails to lead to the best tall man lettering option (e.g., makes names appear too similar, makes names hard to read based on pronunciation), an alternative option is considered. To promote consistency, ISMP suggests following the bolded, tall man lettering schemes provided by FDA and ISMP for the drug names listed in Tables 1 and 2 be followed to promote consistency.