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Liquid medicine dosage instructions for children oftentimes lead to major dosing errors. Previous studies have found that the use of kitchen teaspoons and tablespoons leads to dosing errors, but the pharmaceutical industry continues to use teaspoon units in dose instructions. The purpose of this study was to investigate the extent to which teaspoon units in dosage instructions increase the risk of dosing errors compared to other units.
In this study, 194 university students were randomly assigned to a dose recommendation given in either teaspoons, milliliters, or teaspoons and milliliters. Then, the participants were asked to select a device for measuring the dose. They were given the option of a kitchen teaspoon, a measuring cup with milliliters marks, a measuring cup with teaspoon marks, or a measuring cup with both teaspoon and milliliter marks. The percentage of participants choosing each device in the different conditions was measured.
The results of this study found that the choice of dosing device was significantly influenced by the units of measurement in the dosage instructions. Participants who were given dosing instructions in teaspoons were twice as likely to choose the kitchen teaspoon than those given instructions in milliliters (31.3 vs. 15.4%). Participants given dosing instructions in teaspoons and milliliters were still 1.5 times as likely to choose the kitchen spoon when compared to those given instructions in milliliters.
These results show that the use of spoons to measure liquid medicine can be greatly reduced if dose recommendations were written in milliliters rather than teaspoons. In order to encourage more accurate dosing practices, the FDA and pharmaceutical industry should stop using teaspoon units in dose recommendations and promote the use of other dosing devices such as cups, droppers, and syringes.
Van Ittersum, Koert and Brian Wansink (2016). Stop Spoon Dosing: Milliliter Instructions Cause Fewer Dosage Errors than Spoon Instructions on Liquid Medications. BMC Research Notes, 9(33). doi: 10.1186/s13104-015-1809-1