The number of older adults in the United States who are taking potentially dangerous drug combinations is rising.

One in six older Americans regularly use a mixture of prescription drugs, over-the-counter medications, and dietary supplements, according to a University of Illinois study published today in Science Daily.

Researchers said that is a two-fold increase over a five-year period. The researchers cited a new Medicare rule and the rise of generic drugs as two of the reasons.

“It’s very concerning and it’s probably an underestimation. The situation may be worse,” Dima M. Qato, an associate professor of pharmacy systems, outcomes, and policies at the University of Illinois, told Healthline.

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What Older Adults Are Taking

Qato and her colleagues conducted in-home interviews with more than 2,000 people across the nation, aged 62 to 85 years.

They found the percentage of older adults taking at least five prescription drugs rose from about 30 percent to almost 36 percent between 2005 and 2011.

The researchers pinned the increase on Medicare Part D, changing treatment guidelines, and the rising availability of generic drugs.

They highlighted the drug Zocor, the most commonly prescribed medication among older adults. That drug became available as a generic in 2006. Its use rose from 10 percent to 22 percent between 2005 and 2011.

The researchers also estimated that the use of dietary supplements climbed from 52 to 63 percent during the same time. In particular, the use of omega-3 fish oils among the senior population jumped from about 5 percent to more than 18 percent.

Researchers said this increase came despite limited scientific evidence of the health benefits of these supplements.

Most importantly, researchers said, they identified 15 potentially dangerous combinations from commonly used medications and supplements. More than half involved at least one over-the-counter drug or dietary supplements.

The researchers estimated that the number of older Americans using these mixtures has risen from 8 percent to nearly 15 percent.

Qato noted that the survey information is from 2011 and more generic drugs are now available.

“What that means is more people probably use these drugs now,” she said.

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The Danger Lurking

Qato said the dangers of mixing medications have a wide range.

The combinations can eliminate the effects of prescription drugs, in particular those that are taken for heart health.

She said more dangerous conditions may also arise. These include bleeding, renal failure, and heart attacks or strokes.

Qato said it’s important for older patients to tell their doctors all the pills they are taking. She said doctors and pharmacists should also ask the same questions of their patients.

She thinks more information should be included in drug guidelines on the potential hazards of mixing medications.

“The problem isn’t just with older adults,” said Qato. “It can happen to anyone using multiple medications.”

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