Atlanta—When administering liquid medications, people too often grab a kitchen spoon to dose themselves or their children.

Why is that a problem? Because using teaspoons to measure medicine tends to under-serve by 8.4%, and using tablespoon over-serves by 11.6%, according to a pair of researchers—Koert van Ittersum, PhD, currently of the University of Groningen in The Netherlands (and at the Georgia Institute of Technology in Atlanta when the study was conducted), and Brian Wansink, PhD, of Cornell University in Ithaca, New York.

Now, in a study published recently in BMC Research Notes, Van Ittersum and Wansink suggest that listing the drug facts and dosage information in milliliters makes it more difficult to estimate visually, making it more likely that accurate measuring devices will be used.

For the study, 177 young adults were randomly assigned to one of three conditions where dose recommendations for cough medicine were given in:

• teaspoons (1 teaspoonful every 12 h),
• milliliters (5 mL every 12 h), or
• both teaspoons and milliliters (1 teaspoonful [5 mL] every 12 h).

All three dose recommendations stated: “The FDA recommends against the use of kitchenware to medicate liquid medicines.”

Next, all participants were shown pictures of four different dosing devices:

• a kitchen teaspoon
• a measuring cup with milliliter (mL) marks
• a measuring cup with teaspoon (tsp) marks
• a measuring cup with both milliliter (mL) and teaspoon (tsp) marks.

Participants were then asked which device they would use.

At study initiation, 34.5% reported using kitchen spoons most frequently to measure medicine, and, when given dosage information in teaspoons during the study, 60.9% chose a teaspoon for measurement while none chose the milliliter measuring cup.

When the dosage recommendation was given in milliliters, however, the teaspoon and the measuring cup were equally popular among participants. Participants’ choice of dosing device was significantly influenced by the units of measurement in the instructions, according to the results: Participants who were given dosing instructions in teaspoon units were twice as likely to choose a kitchen teaspoon as those given instructions in milliliter units (31.3% vs. 15.4 %), while those given joint teaspoon/milliliter units were still 1.5 times more likely to select a kitchen teaspoon (23.1% vs. 15.4 %).

“These results indicate that the risk of dosage error decreases by around 50% by simply changing the recommended units of measurement from tea spoons to milliliters,” study authors point out.

“When measuring medicine for ourselves or our children, we often use regular kitchen spoons but they are not accurate measuring instruments,” van Ittersum said in a Cornell Food and Brand Lab press release, “While we feel that we can estimate teaspoon doses, milliliters are much harder to estimate visually, therefore people are more likely to use accurate measuring spoons or cups when given dosage information in milliliters.”

Study authors recommend that the FDA mandate that the pharmaceutical industry avoid using teaspoons on drug facts and dosing information. They also urge pharmacists and other healthcare professionals to emphasize the importance of not spoon-dosing at home, instead using the measuring cups that typically come with liquid medicine.

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