Adolescent use and misuse of marijuana.

Substance use by adolescents and young adults continues to be a serious problem. Marijuana remains the most commonly used illicit substance with close to 50% of high school seniors admitting use at some time. Each year 2.6 million individuals in this country become new users and most are under 19 years old. Individuals who provide health care services to this age group must have an understanding of the drug, its pharmacokinetics, and the many short- and long-term adverse effects. Familiarity with risk factors associated with initiating use can be helpful in screening older children and targeting anticipatory guidance toward those most likely to benefit. This article reviews these issues and includes commentary on a recently published review of treatment programs.