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Is Marijuana a Gateway Drug?: A Deep Dive Into the Data

It’s not an easy question to answer because individual differences, environment, changing social factors, and limitations in available data make it difficult to come to a definitive conclusion on whether marijuana is a gateway drug.

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The gateway drug theory purports that the use of a legal, more socially accepted, or less “harmful” drug like alcohol or marijuana can serve as an entry into the use of “harder” or more harmful drugs like heroin or cocaine.[1] 

Some studies have shown a strong correlation between marijuana use and subsequent use and abuse of other substances.[2] Alternative hypotheses, like the common liability model, contend that marijuana use and misuse of other drugs are influenced by the same risk factors, making it hard to tell if the person would have ended up using other substances even if they never tried marijuana.[3] 

What Does the Data Suggest? 

According to the National Institute of Justice, the Substance Abuse and Mental Health Services Administration (SAMHSA) reports that 118.2 million Americans ages 12 or over have tried marijuana at least once. Of that number, almost all also tried alcohol or tobacco; while 32% used cocaine, 12% tried methamphetamines, and 4% used heroin as well.[4] 

Not everyone who tries marijuana goes on to actively use other drugs, according to their report. The data suggests that only 0.3% have used heroin or cocaine after trying marijuana, and another 0.2% went on to use methamphetamines.[4] 

However, some theories are somewhat backed by research that may support the notion that marijuana leads to the addictive use of other substances. Still, there are alternative theories that are supported by research that say the opposite. Due to these conflicting theories, more research is needed in this area.

The Gateway Drug Theory

The gateway drug theory suggests that marijuana use may be the first step toward a lifelong and life-threatening addiction to other substances. Proponents of this theory argue that marijuana’s psychoactive properties and the high that it creates may trigger interest in other kinds of “highs” or desensitize the user to the risks associated with the drug use in general. 

A study that may support this notion created a theory of four stages of drug consumption based on a 1975 survey of public high school students in New York.[4] Per this theory, the path to addiction starts with beer and wine, continues with tobacco and hard liquor, then moves to marijuana, and ends with use of other illicit substances. Depending on how much and how frequently a person engages in use of the substance at any stage, they may be more or less likely to progress to the next stage, according to the study.[4] 

Though this study may support the idea that marijuana is a gateway to use of illicit substances, it also suggests that use of any mind-altering substance, including alcohol, increases the chance that someone will ultimately progress to abuse of marijuana and then “harder” drugs. 

Correlation vs. Causation

While some studies indicate a link between marijuana use and subsequent abuse of drugs like cocaine or heroin, it is important to distinguish between correlation and causality. Correlation simply establishes statistical relationships among variables without necessarily suggesting an indisputable causal connection. On the other hand, causal means that one thing directly caused the other to happen. 

To determine causation, more stringent research methodologies like longitudinal studies that observe people over an extended period are essential. By following participants over time, researchers can gain greater clarity into whether marijuana directly caused further drug use or whether other factors played a part.

Longitudinal Studies

A study published in the International Journal on Drug Policy looked at lifetime use of marijuana and related rates of abuse of other drugs in an attempt to determine the likelihood of moving onto heavy drugs after using marijuana for any period of time. They found that 44.76% of individuals with a lifetime history of marijuana use have also experimented with other illegal substances.[5]

Why would some move onto other drugs but not others? Mental health was identified as an influential factor, with people who have mental health issues being more likely to experiment with other substances following marijuana consumption. Social networks and peer pressure also played a significant role in subsequent drug use.[5]

Common Liability Model

The common liability model is a theory that shared risk factors contribute to the use of both marijuana and other drugs.[3] Even if marijuana were used first, it is likely that that person would have used any available substance, whether or not they first used marijuana.

There are many risk factors for substance abuse and addiction in general, such as these:[6]

  • Genetics
  • Environment
  • Peer pressure
  • History of trauma
  • Mental health disorders

The presence of these factors makes it more likely that a person will abuse any substance, not just marijuana or other specific drugs.

A Changing Social Landscape

As marijuana is legalized for recreational use in more states, it affects how the drug is perceived in general, reducing stigma surrounding its use. Rates of marijuana use increase following a state legalizing its recreational use.[7] 

As more people use marijuana due to its increased social acceptance, drug use in general might become more normalized. As a result, people might experiment with other drugs, such as hallucinogens, opioids, or stimulants. This strengthens the theory that marijuana is a gateway drug.  

On the other hand, changes to society’s perception of marijuana could discourage use of other drugs. Since marijuana is more socially accepted, some people may feel less inclined to progress to other drugs that bring more intense effects and risks. They may view marijuana use as a full experience unto itself that is safer than use of drugs that are illegal in their state and less socially acceptable.

Will Marijuana Use Lead to Abuse of Other Drugs?

Ultimately, whether or not marijuana use will lead to abuse of or addiction to another substance like heroin or methamphetamine will depend on a range of factors. There’s no evidence that using marijuana will automatically lead to use of other substances, but in some cases, it might.  

Use of marijuana will lower inhibitions and make it more likely that you might get into a dangerous situation. And if marijuana use has become problematic for you, the risks increase. If you have certain risk factors for addiction and you used marijuana at an early age, it’s more likely that you will progress to use of stronger drugs as well.[8] 

If you are concerned about your use of marijuana, help is available. Addiction treatment can help you to stop using all substances of abuse through evidence-based therapies. Contact us today to learn more. 

Updated March 25, 2024
  1. Testing the gateway hypothesis. Miller ML, Hurd YL. Neuropsychopharmacology. 2017;42(5):985-986.
  2. Is marijuana a gateway drug? National Institute on Drug Abuse. Published July 2020. Accessed December 21, 2023.
  3. Common liability to addiction and “gateway hypothesis”: Theoretical, empirical and evolutionary perspective. Vanyukov MM, Tarter RE, Kirillova GP, et al. Drug and Alcohol Dependence. 2012;123:S3-S17.
  4. Is cannabis a gateway drug? Nöel W, Wang J. Key Findings and Literature Review. 2018.
  5. Probability and predictors of the cannabis gateway effect: A national study. Secades-Villa R, Garcia-Rodríguez O, Jin CJ, Wang S, Blanco C. International Journal of Drug Policy. 2015;26(2):135-142.
  6. Risk factors for substance use across the lifespan. Stewart SA, Copeland AL, Cherry KE. The Journal of Genetic Psychology. 2022;184(2):1-18.
  7. Estimating the effects of legalizing recreational cannabis on newly incident cannabis use. Montgomery BW, Roberts MH, Margerison CE, Anthony JC. PLOS ONE. 2022;17(7):1-13.
  8. Marijuana and public health: Risk of using other drugs. Centers for Disease Control and Prevention. Published September 8, 2021. Accessed December 23, 2023.
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