The National Survey on Drug Use and Health of survey of some 67,500 people conducted in the Substance Abuse and Mental Health Services Administration indicates 22.6 million Americans age 12 or older were current illicit drug users in 2010.
Illicit drug use among young adults age 18-25 rose from 19.6-percent in 2008 to 21.2-percent in 2009 and 21.5-percent in 2010.
This increase was driven by an increased rate of marijuana use among this age group. In 2010, 17.4 million Americans were current users of marijuana, compared to 14.4 million in 2007, the survey says.
"Emerging research reveals potential links between state laws permitting access to smoked medical marijuana and higher rates of marijuana use," Gil Kerlikowske, director of National Drug Control Policy, says in a statement.
The survey also finds 55 percent of those age 12 and older who had used prescription pain relievers non-medically in the past 12 months received them from a friend or relative for free and 4.4 percent who misused pain relievers in 2010 say they got the prescription drugs from a drug dealer and 0.4 percent bought it over the Internet.
More than 23.1 million Americans age 12 or older needed specialized treatment for a substance abuse problem, but only 2.6 million received it, officials say.