The proportion of older Americans taking at least five medications or supplements went up in a recent study.

The increase in people using multiple medications - known as polypharmacy - paralleled an increase in the number of older Americans at risk for major drug interactions, researchers found.

"That's a concern from a public health standpoint, because it's getting worse," said Dima Qato, the study's lead author from the University of Illinois at Chicago.

Qato and her colleagues previously reported that polypharmacy is common among older Americans. More than half were taking prescription and nonprescription medications between 2005 and 2006.

There have been a lot of changes in U.S. regulations and the pharmacy market since that time, however. Some of those changes include new and less expensive generic drugs and the implementation of Medicare Part D, which is the prescription component of the government-run health insurance program for the elderly or disabled.

To evaluate the change in polypharmacy over time, the researchers compared the 2005-2006 results to data collected from 2010-2011.

More on this...

Participants in the study were between the ages of 62 and 85 and were living at home. The researchers interviewed 2,351 people in 2005-2006 and 2,206 in 2010-2011.

Overall, about 67 percent were taking five or more medications or supplements in 2010-2011, up from about 53 percent in 2005-2006.

Use of cholesterol-lowering statins rose from about 34 percent to about 46 percent, the researchers reported in JAMA Internal Medicine. The proportion of people taking blood-thinning medications also increased, from about 33 percent to 43 percent, and use of omega-3 fish oil pills rose from about 5 percent to about 19 percent.

Along with the increase in polypharmacy, the researchers found the risk of major drug interactions nearly doubled, going from about 8 percent to about 15 percent.

"I think we have to keep in mind that while it's important to improve access to medications, we need to make sure they're used safely," said Qato.

On one hand, the new results can be seen as positive, said Dr. Michael Steinman, a gerontologist at the University of California, San Francisco.

"We're treating more people with medications that could potentially help them," he said. "But when people have four or five chronic conditions, medications quickly balloon to a large number."

It's important to ensure clear communication between everyone involved in a patient's care, including the patient, said Steinman, who wrote an editorial accompanying the new study.

"You can get rid of problems and excess medications by talking with your doctors," he said.

A separate study reported in the same issue of the journal found that nearly 42 percent of adults did not tell their doctors about the use of complementary or alternative medicine, which includes - among other things - supplements, herbs, homeopathy, special diets and acupuncture.

Many patients said they didn't tell their doctors about these alternative medicines because they weren't asked or because their doctors didn't need to know that information, write Judy Juo and Pamela Jo Johnson, of the University of Minnesota in Minneapolis.

"If a person is talking with their doctor about the medications they're using, they should be talking about all the medications they're using," said Steinman.