If you’re one of scores of Americans who mix multiple prescription drugs and over-the-counter supplements to help combat or prevent health issues such as heart disease, high cholesterol and high blood pressure, you may want to consider what you’re taking. New findings published in JAMA Internal Medicine suggest that this combination may lead to dangerous interactions, CNN reports.

For the study, a team of researchers at the University of Illinois at Chicago examined the use of medications and supplements in a wide array of older adults, ages 62 to 85, between 2006 and 2011. Next, scientists used a database of reported and predicted interactions to determine whether the 20 most common prescription drugs and supplements used by study participants were likely to cause an adverse reaction when taken together.

Findings showed that in just five years, the number of people taking five or more medications or supplements rose from a little more than 53 percent to almost 67 percent. Scientists also found that 16 different combinations of prescription drugs, over-the-counter meds and supplements taken during the study period were predicted to increase the risk of a dangerous interaction.

One common prescription drug researchers mentioned in their report was warfarin, a blood thinner commonly administered to patients at risk of cardiovascular disease. When taken with popular omega-3 fish oil supplements, the two substances increase the risk of bleeding for certain patients.

“We are trying to improve access to essential prescription medications like statins that could prevent heart disease and improve survival, but we are not prioritizing enough how safe these medications are in the context of all the prescription and nonprescription medications older adults are using, said Dima M. Qato, PhD, an assistant professor of pharmacy systems, outcomes and policy at the University of Illinois at Chicago, and lead author of the study.

Significantly, the journal published another paper suggesting that many patients don’t tell their doctors about the nonprescription drugs and supplements they are taking. Researchers noted that the takeaway from these studies is that health care workers should ask their patients what therapies they’re using, and patients should also share this information with their doctors.

Did you know that certain foods can interfere with the way our bodies process prescription medications? Click here to learn more.