Cannabis use could be a “gateway” out of more harmful substance use, according to new research

published on March 29, 2018

Cannabis use makes it less likely some people who use drugs will start injecting drugs, according to research from the British Columbia Centre on Substance Use (BCCSU).

Research published in Drug and Alcohol Review (March 2018, Volume 37, Issue 3) found street-involved youth who used cannabis were less likely to begin using drugs via injection. The study followed 481 participants who were injection-naïve at the time of recruitment.  From study enrolment, the median time to injection initiation was 13 months. However, daily cannabis use was associated with a 34% decrease in the rate of injection initiation.

The average age of injection initiation is between 19 and 23 years, and street-involved youth are known to be at elevated risk of initiating injection drug use and engaging in high-risk drug practices such as needle sharing. People who use injection drugs also face increased risk of infection with HIV and hepatitis C, accidental overdose, stigmatization, and criminalization.

“One common perception about cannabis is that it’s a so-called gateway drug to other, higher risk drug use. However, our study found the opposite,” says senior author Dr. M-J Milloy, research scientist at BCCSU and Assistant Professor at the University of British Columbia.

Previous research from the BCCSU supports the findings in this latest study. In an article published last year in Harm Reduction Journal, researchers found that cannabis use may aid in quitting injection drug use. Another study published last year in International Journal of Drug Policy described how youth attempt to reduce harms stemming from addiction, including using cannabis to reduce or eliminate use of drugs they considered more harmful, such as crystal meth, crack cocaine, and opioids.

“These findings suggest the risks and possible benefits of cannabis use – particularly among high-risk youth – are not fully understood,” says Dr. Milloy. “With the impending legalization of cannabis in Canada, future studies into the impact of cannabis use on high-risk drug behaviours are needed.”

Data for the studies were derived from the At-Risk Youth Study (ARYS), a prospective cohort of street-involved youth in Vancouver aged 14-26 years, and looked at the results of interviews conducted between September 2005 and May 2015.

The study can be found here: