When buying over-the-counter medications for their children, parents may expect a quick solution to their child's ailment, but a new study shows that measuring out that medication provides its own challenges.

Researchers looked at 200 of the top-selling nonprescription liquid medications on shelves and found that nearly all had inconsistent directions: The labels on the devices for measuring doses didn't match up with the dosing instructions.

"We feel that is very important to give parents medication instructions that are clear and easy to understand," said one of the study's lead researchers, Dr. H. Shonna Yin, an assistant professor of pediatrics at New York University.

Of the products that came with a dosing device, such as a spoon or a cup, 99 percent had markings and instructions that didn't match, the study found. "That really adds to the confusion," Yin said.

Problems with the dosing devices included a lack of markings for the dose that was listed on the packaging; extraneous measurements; unusual abbreviations for dosing; and the use of units of measurement that parents may be unfamiliar with, such as ccs (cubic centimeters) or drams.

About three-quarters of the products came with a measuring device. But even the other products presented dosing problems, the researchers said.

Instructions that relied on the abbreviations for "tablespoon" (tbsp) and "teaspoon" (tsp) can be confused by parents, said the researchers, which could lead to a child getting three times as much medication as needed or only a third as much. In the study, one medication is shown in which the packaging calls for dosing in tablespoons but the measuring cup is labeled in "tsp."

The study also noted that some parents use a measuring spoon from the kitchen.

"Kitchen spoons are really inaccurate," Yin said, and people vary in how much they fill those spoons.

The researchers recommended that a measuring device be included with all products, that the device be labeled with only the measurements called for in the packaging instructions, that the dose measurement match the packaging instruction, and that one standard be used for units (milliliters, for example).

The study will be published tomorrow (Dec. 1) in the Journal of the American Medical Association.

Dr. Darren DeWalt, an assistant professor in the department of medicine and clinical epidemiology at the University of North Carolina, wrote an editorial accompanying the study. He said the problems were troubling because when researchers have looked at people's use of dosing instructions, error rates have been as high as 50 to 60 percent.

In November 2009, the FDA released new voluntary guidelines for labeling children's medications, so the problem may have lessened.

But, DeWalt told MyHealthNewsDaily, "I don't think the current FDA guidance is clear enough, and more work needs to be done to get the error rate lower."

While he declined to give specific number, he said it certainly could become "less than 50 percent."

Yin said there has been some response, from government groups and the Consumer Health Products Association (CHPA) — a trade group for companies that sell over-the-counter medications – in noting the need for better labeling and issuing new voluntary guidelines.

As of press time, the CHPA had not provided a response to the study.

However, she said there is a need for go further.

"Because there are so many affected, the authors and I feel there is an important need to push for standards and regulations," Yin said.

This article was provided by MyHealthNewsDaily, a sister site to LiveScience.