Experts agree that the use of marijuana is not causally linked to the use of other illicit substances
“This study is the first to use nationally representative data across all 50 states and the District of Columbia to comprehensively explore the broader impacts of RMLs [recreational marijuana laws], providing some of the first evidence on how marijuana legalization is affecting illicit drug use, heavy alcohol use, arrests for drug and non-drug offenses, and objectively-measured adverse drug-related events including drug-related overdose deaths and admissions into substance abuse treatment services. … [W]e find little compelling evidence to suggest that RMLs result in increases in illicit drug use, arrests for part I offenses, drug-involved overdoses, or drug-related treatment admissions for addiction.”
“Marijuana use has been proposed to serve as a ‘gateway’ that increases the likelihood that users will engage in subsequent use of harder and more harmful substances, known as the marijuana gateway hypothesis (MGH). The current study refines and extends the literature on the MGH by testing the hypothesis using rigorous quasi-experimental, propensity score-matching methodology in a nationally representative sample. … Results from this study indicate that marijuana use is not a reliable gateway cause of illicit drug use. As such, prohibition policies are unlikely to reduce illicit drug use.”
“There is compelling and enduring evidence that marijuana is not a gateway drug, … Yet, non-evidence-based political factors on both the left and the right remain the reason for the persistence of the gateway myth.”
“The psycho-social observation that the use of some psychoactive substances (‘drugs’) is often followed by the use of other and more problematic drugs has given rise to a cluster of so-called ‘gateway drug hypotheses,’ and such hypotheses have often played an important role in developing drug use policy. The current essay suggests that drug use policies that have drawn on versions of the hypothesis have involved an unjustified oversimplification of the dynamics of drug use, reflecting the interests of certain stakeholders rather than wise social policy. The hypothesis should be retired.”
Sequentially, most consumers of illicit substances first experimented with either alcohol or tobacco
“Alcohol is the most commonly used substance, and the majority of polysubstance using respondents consumed alcohol prior to tobacco or marijuana initiation. Respondents initiating alcohol use in sixth grade reported significantly greater lifetime illicit substance use and more frequent illicit substance use than those initiating alcohol use in ninth grade or later. … Our results … assert that the earlier one initiates alcohol use, the more likely that they will engage in future illicit substance use.”
Statistically, the overwhelming majority of people to try marijuana do not go on to use other illicit drugs, and most typically cease their use of marijuana by middle age
“[T]he majority of people who use marijuana do not go on to use other ‘harder’ substances.”
“Substance use tends to decline towards the end of young adulthood. This decline is true for alcohol as well as illicit drug use. … For marijuana, … peak use occurred at about age 19, remained stable for the next four to five years, and then declined.”
In jurisdictions where marijuana is legally accessible, adults typically report decreasing their use of other controlled substances. In this sense, marijuana appears to act more as a potential ‘exit drug’ rather than as an alleged ‘gateway’
“This study assessed (1) trends in alcohol, nicotine, and nonprescribed pain reliever use and (2) changes in associations of cannabis use with these other substances among young adults in Washington State after nonmedical cannabis legalization. …Contrary to concerns about spillover effects, implementation of legalized nonmedical cannabis coincided with decreases in alcohol and cigarette use and pain reliever misuse. The weakening association of cannabis use with the use of other substances among individuals ages 21-25 requires further research but may suggest increased importance of cannabis-specific prevention and treatment efforts.”
“[F]indings on cannabis substitution effect and the biological mechanisms behind it strongly suggest that cannabis could play a role in reducing the public health impacts of prescription and non-prescription opioids. … The growing body of research supporting the medical use of cannabis as an adjunct or substitute for opioids creates an evidence-based rationale for governments, health care providers, and academic researchers to consider the implementation and assessment of cannabis-based interventions in the opioid crisis.”
“Among respondents that regularly used opioids, over three-quarters (76.7%) indicated that they reduced their use since they started medical cannabis. This was significantly ( p < 0.0001) greater than the patients that reduced their use of antidepressants (37.6%) or alcohol (42.0%). Approximately two-thirds of patients decreased their use of anti-anxiety (71.8%), migraine (66.7%), and sleep (65.2%) medications following medical cannabis.”
“Findings include high self-reported use of cannabis as a substitute for prescription drugs (63%), particularly pharmaceutical opioids (30%), benzodiazepines (16%), and antidepressants (12%). Patients also reported substituting cannabis for alcohol (25%), cigarettes/tobacco (12%), and illicit drugs (3%).”
“These patient-reported outcomes support prior research that individuals are using cannabis as a substitute for prescription drugs, particularly, narcotics/opioids, and independent of whether they identify themselves as medical or non-medical users. This is especially true if they suffer from pain, anxiety and depression.”
“Substituting cannabis for one or more of alcohol, illicit drugs or prescription drugs was reported by 87% of respondents, with 80.3% reporting substitution for prescription drugs, 51.7% for alcohol, and 32.6% for illicit substances. … The finding that cannabis was substituted for all three classes of substances suggests that the medical use of cannabis may play a harm reduction role in the context of use of these substances, and may have implications for abstinence-based substance use treatment approaches.”
In clinical settings, marijuana use is associated with reduced cravings for cocaine and opiates
“In this longitudinal study, we observed that a period of self-reported intentional use of cannabis … was associated with subsequent periods of reduced use of crack [cocaine]. … Given the substantial global burden of morbidity and mortality attributable to crack cocaine use disorders alongside a lack of effective pharmacotherapies, we echo calls for rigorous experimental research on cannabinoids as a potential treatment for crack cocaine use disorders.”
“Most of the subjects in our study ceased to use crack cocaine and reported that the use of cannabis had reduced their craving and produced subjective and concrete changes in their behavior helping them overcome addiction.”
