It’s a theory that’s been presented as fact by marijuana foes since the Harry Anslinger era: By partaking of cannabis, humans risk being inexorably led to harder drugs like cocaine and heroin.
This “cannabis leads to harder narcotics” argument gets trotted out whenever efforts to normalize cannabis are underway, and the expansion of marijuana legalization across North America has predictably breathed new life into this old trope. So let’s settle it once and for all: Is cannabis a “gateway drug”?
On the “yes” side, the strongest evidence comes from the National Institute on Drug Abuse. “Early exposure to cannabinoids in adolescent rodents decreases the reactivity of brain dopamine reward centers later in adulthood,” reports NIDA. “To the extent that these findings generalize to humans, this could help explain the increased vulnerability for addiction to other substances of misuse later in life that most epidemiological studies have reported for people who begin marijuana use early in life.”
NIDA also cites THC’s alleged ability to “prime” the brain for enhanced responses to other drugs, via the phenomenon known as “cross-sensitization”: “[R]ats previously administered THC show heightened behavioral response not only when further exposed to THC but also when exposed to other drugs such as morphine,” reports NIDA.
However, NIDA notes that “cross-sensitization is not unique to marijuana. Alcohol and nicotine also prime the brain for a heightened response to other drugs and are, like marijuana, also typically used before a person progresses to other, more harmful substances.”
Beyond such generalities and rat-based supposition lies the supporting evidence for the “No, cannabis is not a gateway drug” argument.
Exhibit A: the countless living humans who have experienced cannabis—and even incorporated it as a regular part of their lives—without being inspired to progress to dangerous narcotics like cocaine and heroin. (In fact, cannabis is increasingly being recognized as a tool to help addicts get off dangerous drugs.)
The majority of cannabis’ potential as a gateway drug comes from its prohibition.
Exhibit B: the fact that the majority of cannabis’ potential as a gateway drug comes from its prohibition, which requires those who want cannabis to buy it through the illegal market, often from dealers with more to sell than cannabis and incentive to sell as much of everything as possible. In this scenario, the primary force driving cannabis users to harder narcotics are illegal cannabis dealers selling harder narcotics. The prohibition creates the connection. Remove the prohibition and the connection between cannabis and dangerous narcotics falls away.
The verdict: No, cannabis is not a “gateway drug.” A puff of weed will not lead directly to a needle in your arm. It may, however, lead you to eat deep-fried things you regret. YOU HAVE BEEN WARNED.