A spoonful of sugar may make the medicine go down, but be aware of the size of the spoon you’re using. A new study shows that people who use kitchen spoons to measure liquid medicine are frequently miscalculating the size of the dose they’re delivering.

Why is this so dangerous? The dose might actually seem smaller on a larger spoon. This could lead to overdosing. In fact, a 1992 study of dosing errors found that failing to distinguish between teaspoons and tablespoons is a leading cause of overdosing.

This is especially problematic with liquid medicines that include acetaminophen, the active ingredient in Tylenol. Overdosing on this medication can lead to serious illness, liver failure and even death.

For the study, researchers told students to pour five milliliters of cold medication into spoons of various sizes… a five milliliter teaspoon, a fifteen milliliter tablespoon and a forty-five milliliter serving spoon.

First the students had to pour the medication into the five milliliter spoon so they could gauge the proper amount. Then they had to pour the same amount into the other spoons.

The result? Even though the students had just seen the proper dosage, there was a twenty percent difference in the amount they poured into the other spoons. The students underdosed by an average of eight percent in the medium spoon and overdosed by about twelve percent using the large spoon.

The moral of the story? Take the time to use a measuring cap or the correct-sized dosing spoon. Because the whole idea of taking medicine to begin with is to get better, not make things worse.