Get facts on marijuana—the most commonly used illicit drug in the U.S.—including its effects and information on marijuana surveillance, laws and policies, and prevention guides.
Marijuana, or Cannabis, refers to the dried leaves, flowers, stems, and seeds from the hemp plant Cannabis sativa, which contains the psychoactive (mind-altering) chemical delta-9-tetrahydrocannabinol (THC), as well as other related compounds. This plant material can also be concentrated in a resin called hashish or a sticky black liquid called hash oil. THC is believed to be the main chemical ingredient that produces the psychoactive effect. Marijuana is often smoked in hand-rolled cigarettes (joints), pipes, or water pipes (bongs). People also smoke it in blunts, which are partly or completely emptied cigars filled with marijuana. Marijuana is also mixed in food (edibles) or brewed as tea.
The short-term effects of marijuana include problems with memory and learning, distorted perception, difficulty in thinking and problem-solving, and loss of coordination. Among youth, heavy cannabis use is associated with cognitive problems and increased risk of mental illness.
Learn more about marijuana.
Monitoring trends that impact health, such as trends in substance use, is important to inform services and policy. This is especially true for marijuana given recent changes in state laws and policies. SAMHSA tracks these trends using data from the National Survey on Drug Use and Health (NSDUH). NSDUH collects information about the use of illicit drugs, alcohol, and tobacco, including marijuana, among noninstitutionalized people aged 12 or older in the United States.
Find historical NSDUH trend data from 2002 to 2014 on use, attitudes, and perceptions of marijuana at the national level, access the surveillance summary report in the CDC Morbidity and Mortality Weekly Report and state level.
According to the NSDUH 2015 annual report – 2015 (PDF | 2.15 MB):
- Marijuana use in the past month increased from 6.2% in 2002 to 8.3% (approximately 22.2 million people) in 2015 among people aged 12 or older.
- Marijuana use was most prevalent among people aged 18 to 25 (with 19.8% using it in the past month)
- 0% of people aged 12 to 17 reported marijuana use in the past month
Laws and Policies
State-level laws and policies on marijuana use (for recreational or medical use) have changed over the past decade; however it remains an illegal substance (Schedule I drug) under federal law. As state laws continue to change, the Department of Justice issued a guidance regarding marijuana enforcement – 2013 for federal prosecutors regarding marijuana enforcement under the Controlled Substance Act. In response to these and other emerging public health issues on marijuana, SAMHSA participates on the Department of Health and Human Services’ (HHS) Behavioral Health Coordinating Council (BHCC) to ensure that all of the mental health and substance use projects and programs that HHS operating and staff divisions lead are synchronized. The BHCC has various standing subcommittees, including one that addresses marijuana related issues.