The agency's 2006 survey on drug abuse and health found that more than 5 percent of teenagers and young adults had misused cough and cold medicines and indicated that these people also had experimented frequently with illicit drugs.
Nearly 82 percent also had used marijuana. Slightly less than half also used inhalants or hallucinogens, such as LSD or Ecstasy, the agency said.
The cough suppressant DXM is found in more than 140 cough and cold medications available without a prescription. When taken in large amounts, DXM can cause disorientation, blurred vision, slurred speech and vomiting.
Among all persons aged 12 to 25, the rate of past year misuse among whites was 2.1 percent, which was three times higher than the level for blacks, 0.6 percent, and also significantly higher than the level for Hispanics, 1.4 percent.
"While increasing attention has been paid to the public health risk of prescription drug abuse, we also need to be aware of the growing dangers of misuse of over-the-counter cough and cold medications, especially among young people," said Terry Cline, the agency's administrator.
More on the study: samhsa.gov