We've all done it. The bottle of Pepto-Bismol says to take two tablespoons, so you grab the nearest spoon from the silverware drawer and drink down two of those. It's probably pretty close, right?

Maybe not. With all the different sizes and shapes of spoons out there — soup spoons, dessert spoons, grapefruit spoons and coffee spoons, to name just a few — who knows if the spoon you chose is actually close to a tablespoon.

And when it comes to children, that lack of precision can be dangerous.

Forty percent of parents make significant errors in measuring medication for their children, according to a study published Monday in the journal Pediatrics. And they were twice as likely to make an error when doses were listed in teaspoons or tablespoons rather than milliliters, in part because they measured out the medication using an ordinary spoon.

"Terms like 'teaspoon' and 'tablespoon' inadvertently endorse the use of kitchen spoons, which can vary in size and shape," says Dr. H. Shonna Yin, a pediatrician at the New York University School of Medicine and lead author on the study.

In the study, 30 percent of parents who thought of the medication dose in terms of teaspoons or tablespoons ended up using a kitchen spoon rather than a measuring device provided with the medication, compared with only 1 percent who thought of the medication dose in terms of milliliters. The use of kitchen spoons led to a greater frequency of dosing errors, which were defined as measured doses that were 20 percent higher or lower than the prescribed amount.

"We recommend that parents always use standard dosing tools like syringes and droppers," says Yin.

Confusion over liquid medication doses for children is a huge safety issue, contributing to upward of 10,000 calls to national poison control centers annually. The problem stems in part from the lack of a standard measurement unit on liquid medications. Parents may face instructions with dosing units ranging from the familiar — teaspoons and tablespoons — to the seemingly archaic — drams and dropperfuls.

Organizations including the Centers for Disease Control and Prevention, the Food and Drug Administration and the American Academy of Pediatrics have called for doctors, pharmacists and drug manufacturers to adopt a standard unit of measure for liquid medications, with the milliliter being the top pick.

Many drug companies have already moved to using more standardized labeling that combines milliliters and teaspoons, according to Barbara Kochanowski of the Consumer Healthcare Products Association, a trade group for manufacturers of over-the-counter medications.

But some health literacy advocates are still hesitant to get rid of the traditional teaspoon and tablespoon measures altogether, Kochanowski says, out of fear that the less familiar milliliter might cause more confusion.

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