Perceived health, medical, and psychiatric conditions in individual and dual-use of marijuana and nonprescription opioids.

Marijuana and nonprescription opioids remain the two most commonly used illicit substances in the United States. They have commonalities, yet the use of both at the same time may have a greater impact on psychological and health outcomes. Research is needed to determine whether dual-use is associated with more negative outcomes than individual substance use.We used the National Epidemiologic Survey of Alcohol and Related Conditions (NESARC) Wave...