Medication error due to ambiguous labelling of a commercial product

Medication errors may involve prescribing, dispensing, preparation and administration of drugs. We report a case in which an administration error occurred due to ambiguous labelling of a commercial drug. Tablets were packed in sets of two tablets per blister with the print on the blister 'Zelitrex 500', making the amount of drug per tablet unclear. A short survey among nurses and pharmacy technicians showed that the majority interpreted the strength of the tablets incorrectly. This case shows that, despite regulations for controlling and accepting labelling before marketing, ambiguous labelling may occur and can lead to medication errors.