"Much of our team's previous research focus has been on people's ability to take medications safely and to understand how cognitive function affects that," said lead author Jennifer L. Lenahan, formerly of the Health Literacy and Learning Program in the Feinberg School of Medicine at Northwestern University in Chicago.

"We noticed anecdotally in a number of other studies that patients had a lot of trouble identifying their medications."

Even with proper labeling, many people struggle with organizing and taking medications correctly. Patients may recognize that a pill has a certain look but generic medications frequently change their look, which can be confusing, the authors said.

The researchers interviewed a group of Midwestern safety-net patients over age 50 and with high blood pressure to evaluate their knowledge of drug names and dosages or their pills' visual characteristics. They also tested their health literacy and asked them about recent hospitalizations or visits to the emergency department.

Specifically, the authors honed in on "identification strategies, self-reported adherence and health outcomes. Patients who were dependent on the visual identification of their prescription medicine reported worse adherence. In addition, they had significantly lower rates of blood pressure control and greater risk of hospitalization," they wrote.

In general, patients had trouble correctly naming their medications, said Lenahan, and this ability correlated with levels of health literacy. And not surprisingly, the authors said, "patients who could not identify their medications by either name or appearance were more likely to self-report poorer adherence than were those who could identify their medications."

"The work by Lenahan and colleagues further demonstrates the need to counsel patients on safe and appropriate medication use and ensure that every patient has a full understanding of the medications they have been prescribed," said Stacy Cooper Bailey, Ph.D., M.P.H. at the University of North Carolina Eshelman School of Pharmacy. "This is essential to promoting patient safety and ensuring high quality care. This article is unique in that it links patients' knowledge of their medication names to blood pressure control and healthcare utilization."

Bailey also said the report shows the potential danger of relying solely on visual descriptions of medications. "As the appearance of certain drugs may vary over time and patients are often switched from brand name drugs to generics that are a different size, shape or color, ensuring patients know the actual name of their medications is key," she said.