Nearly half of all Americans -- 48 percent -- took at least one prescription drug in a one-month period in 2007-2008, a four-percentage-point hike over a decade, researchers found.
Among those 60 and older, 88.4 percent took at least one prescription medication, as did nearly a quarter of those under 12 (22.4 percent), Dr. Charles F. Dillon of the CDC's National Center for Health Statistics and colleagues reported in a data brief.
The 10-year jump is an increase that translates to "millions of people," Dillon told MedPage Today in a telephone interview.
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The percentage of those who use two or more prescription drugs rose from 25 percent to 31 percent over the decade from 1999 to 2008, and those using five or more jumped from 6 percent to 11 percent.
Dillon said he and his colleagues "thought this was just incredible," and noted that the finding is particularly worrisome in the older population. More than three-quarters of those 60 and older used two or more prescription drugs and 36.7 percent took five or more.
That likely reflects the need to treat many of the diseases that commonly occur in this age group, the researchers said.
But "we know there is a safety risk in that group," Dillon said, referring to the potential harms of drug interactions.
He called for more research into this trend because it is "really a concern."
Certain drugs were used more commonly by different age groups. Among children younger than 12, 5.7 percent were on bronchodilators for asthma. A similar percentage of those 12 to 19 were on central nervous system drugs, most often to treat attention deficit hyperactivity disorder (ADHD).
For those 20 to 59, antidepressants were the most commonly prescribed drug, with 10.8 percent of this population taking them, followed closely by painkillers (10.1 percent) and cholesterol-lowering agents (8.4 percent).
That latter class was the most commonly taken by those 60 and older, with 44.9 percent on a lipid-lowering drug. Beta-blockers and diuretics to treat high blood pressure and heart disease ranked second and third, respectively (26.4 percent and 19.9 percent).
The researchers also found that women were more likely to use prescription drugs than men -- 53.3 percent compared with 43.2 percent.
Overall, total spending on prescription drugs in the U.S. was $234 billion in 2008 -- more than double the amount spent in 1999, the researchers said.
The findings come from an analysis of data from the National Health and Nutrition Examination Survey (NHANES).