THURSDAY, Sept. 2 (HealthDay News) -- Over the last 10 years, the percentage of Americans who took at least one prescription drug in the past month increased from 44 percent to 48 percent, says a federal government study released Thursday.

Use of two or more drugs increased from 25 percent to 31 percent, and the use of five or more drugs increased from 6 percent to 11 percent, according to the analysis of data from the National Health and Nutrition Examination Survey (NHANES).

The study also found that 20 percent of children and 90 percent of adults aged 60 and older reported using at least one prescription drug in the past month, said the U.S. Centers for Disease Control and Prevention researchers.

Spending on prescription drugs in the United States totaled more than $234.1 billion in 2008, more than double the amount spent in 1999, they found.

The most commonly used types of drugs in 2007-2008 included: cholesterol-lowering drugs, or statins, for older people; asthma medicines for children; antidepressants for middle-aged adults; and central nervous stimulants for adolescents.

Access to health care and health insurance are important factors in the use of prescription medicines. People with a regular place for health care were 2.7 times more likely to have used prescription drugs in the past month than those without a consistent place for health care, and people with health insurance were nearly twice as likely to have used at least one prescription drug than those without insurance. Among those with health insurance, those with a prescription drug benefit were 22 percent more likely to use prescription drugs than those without this benefit, the researchers noted.

The use of multiple prescription drugs varied by age. Among children younger than 12 years, less than 10 percent used two or more prescription drugs in the past month and only 1 percent used five or more. Among adults aged 60 and older, more than 76 percent used two or more prescription drugs and 37 percent used five or more.

The higher drug use among seniors reflects the need to treat the many diseases that commonly occur in this age group, the researchers said. However, they noted that the use of multiple medications can lead to harmful drug interactions, failure to take all prescribed medications, and increased health care costs.

The study also found that women were more likely than men to use prescription drugs and that whites had the highest prescription drug use while Mexican Americans had the lowest level of use.

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