More than one-tenth of Americans were current users of illicit drugs in 2014, and drug use among adults – marijuana in particular – was on the rise.

An estimated 27 million people, or 10.2% of Americans, used an illicit drug within the previous month, according to the 2014 National Survey on Drug Use and Health (NSDUH), released Sept. 10 by the Substance Abuse and Mental Health Services Administration (SAMHSA).

About 22 million of those people used marijuana within the previous month, and 4.3 million took prescription pain relievers for nonmedical purposes.

Some 8.4% of Americans aged 12 and older reported current marijuana use, an increase from previous survey years, and 1.6% reported current nonmedical use of pain drugs, a trend that has remained fairly steady, according to the survey.

A significant uptick in nonmedical use of marijuana was seen among adults aged 26 and older, Kana Enomoto, SAMHSA’s acting administrator, said at a Sept. 10 news conference.

Some 6.6% of these adults, or about 13.5 million people, reported being users of marijuana last year, compared with 5.6% in 2013 (P less than .5). Steady increases in marijuana use in this age group have been noted for about a decade.

Heroin use also was higher than in previous years, with an estimated 435,000 users in the United States in 2014, a statistically significant jump from 0.1% of the population aged 12 and older in 2013 to 0.2% last year, with most of the increase driven by people 26 and older.

An estimated 1.5 million Americans, or 0.6% of the population aged 12 and older, were current users of cocaine, including some 354,000 current users of crack cocaine. Cocaine use was similar to patterns seen in recent years.

Overall, current illicit drug use trends appeared to be holding steady or declining in younger age groups, but the increases in adult use are “concerning,” particularly for heroin, said Ms. Enomoto.

Recent declines in alcohol and tobacco use among young people appeared to be holding up. Among adolescents aged 12-17, 4.9% had smoked cigarettes in the previous month, down from 5.6% in 2013 and 6.6% in 2012.

Alcohol use and use patterns among young people were little changed from 2013, and overall incidence of substance use disorders hovered at 8.1% for 2014 among people 12 and older.

The incidence of mental health disorders, including any mental illness and serious mental illness (18.1% and 4.1% of adults over 18, respectively), remained little changed from recent years. Co-occurring mental illness and substance use disorders were at 3.3% of all adults, similar to rates seen since 2006.

The NSDUH data were collected through face-to-face interviews with nearly 68,000 Americans in 2014.