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Marijuana Fast Facts and Fact Sheets

Fast Facts

  • Marijuana is the most commonly used illegal drug in the United States, with approximately 22.2 million users each month.1
  • Research shows that about 1 in 10 marijuana users will become addicted. For people who begin using before the age of 18, that number rises to 1 in 6.2-4
  • Marijuana use directly affects the brain — specifically the parts of the brain responsible for memory, learning, attention, decision making, coordination, emotions, and reaction time. Developing brains, like those in babies, children, and teens, are especially susceptible to the adverse effects of marijuana.5-6
  • Eating foods or drinking beverages that contain marijuana have some different risks than smoking marijuana, including a greater risk of poisoning.7-8
  • Long-term or frequent marijuana use has been linked to increased risk of psychosis or schizophrenia in some users.10-12
  • Using marijuana during pregnancy may increase the baby’s risk for developmental problems.13-19


  1. Results from the 2015 National Survey on Drug Use and Health: Detailed Tables, SAMHSA, CBHSQ. Accessed October 11, 2016.
  2. Lopez-Quintero, C., et al., Probability and predictors of transition from first use to dependence on nicotine, alcohol, cannabis, and cocaine: results of the National Epidemiologic Survey on Alcohol and Related Conditions (NESARC). Drug Alcohol Depend, 2011. 115(1-2): p. 120-30.
  3. Hall, W. and L. Degenhardt, Adverse health effects of non-medical cannabis use. Lancet, 2009. 374(9698): p. 1383-91.
  4. Budney, A.J., J.D. Sargent, and D.C. Lee, Vaping cannabis (marijuana): parallel concerns to e-cigs? Addiction, 2015. 110(11): p. 1699-704.
  5. Meier, M.H., et al., Persistent cannabis users show neuropsychological decline from childhood to midlife. Proc Natl Acad Sci U S A, 2012. 109(40): p. E2657-64.
  6. Filbey, F.M., et al., Long-term effects of marijuana use on the brain. Proc Natl Acad Sci U S A, 2014. 111(47): p. 16913-8.
  7. Monte, A.A., R.D. Zane, and K.J. Heard, The implications of marijuana legalization in Colorado. JAMA, 2015. 313(3): p. 241-2.
  8. Wang, G.S., G. Roosevelt, and K. Heard, Pediatric marijuana exposures in a medical marijuana state. JAMA Pediatr, 2013. 167(7): p. 630-3.
  9. Berger, E., Legal marijuana and pediatric exposure pot edibles implicated in spike in child emergency department visits. Ann Emerg Med, 2014. 64(4): p. A19-21.
  10. Di Forti, M., et al., Daily use, especially of high-potency cannabis, drives the earlier onset of psychosis in cannabis users. Schizophr Bull, 2014. 40(6): p. 1509-17.
  11. Di Forti, M., et al., High-potency cannabis and the risk of psychosis. Br J Psychiatry, 2009. 195(6): p. 488-91.
  12. Di Forti, M., et al., Proportion of patients in south London with first-episode psychosis attributable to use of high potency cannabis: a case-control study. Lancet Psychiatry, 2015. 2(3): p. 233-8.
  13. Mark, K., A. Desai, and M. Terplan, Marijuana use and pregnancy: prevalence, associated characteristics, and birth outcomes. Arch Womens Ment Health, 2016. 19(1): p. 105-11.
  14. Fried, P.A., B. Watkinson, and R. Gray, Differential effects on cognitive functioning in 9- to 12-year olds prenatally exposed to cigarettes and marihuana. Neurotoxicol Teratol, 1998. 20(3): p. 293-306.
  15. Leech, S.L., et al., Prenatal substance exposure: effects on attention and impulsivity of 6-year-olds. Neurotoxicol Teratol, 1999. 21(2): p. 109-18.
  16. Goldschmidt, L., et al., Prenatal marijuana exposure and intelligence test performance at age 6. J Am Acad Child Adolesc Psychiatry, 2008. 47(3): p. 254-63.
  17. Campolongo P, Trezza V, Ratano P, Palmery M, Cuomo V. Developmental consequences of perinatal cannabis exposure: behavioral and neuroendocrine effects in adult rodents.
  18. Psychopharmacology (Berl) 2011;214:5–15. Warner, T.D., D. Roussos-Ross, and M. Behnke, It’s not your mother’s marijuana: effects on maternal-fetal health and the developing child. Clin Perinatol, 2014. 41(4): p. 877-94.
  19. Colorado Department of Public Health and Environment. Monitoring Health Concerns Related to Marijuana in Colorado: 2014. 2015 [cited 2016 July 11, 2016].
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