Why Tobacco and Cannabis Use So Often Go Together | Research

The takeaway

A review of co-morbid tobacco and cannabis use found that each substance promotes dependence on the other through shared neurobiological mechanisms, common route of administration, and gateway effects in both directions.

Read this if you use both tobacco and cannabis and are considering quitting one or both.

Cigarette smokers have accelerated relapse rates when trying to quit cannabis

What the researchers found

This review examined why tobacco and cannabis are so frequently used together and why co-use complicates treatment of both substances.

The evidence showed bidirectional effects: tobacco use increases the likelihood of becoming cannabis dependent, and cannabis use promotes transition to heavier tobacco use. Tobacco smoking also threatens cannabis cessation, with cigarette smokers showing increased and accelerated relapse rates when trying to quit cannabis.

The review identified multiple mechanisms for co-use: synergistic neurobiological effects (both affect the endocannabinoid and nicotinic acetylcholine systems), compensatory effects (one substance modifying the effects of the other), shared route of administration (smoking), and both addiction vulnerability and gateway hypotheses operating in both directions.

Why it matters

Most addiction treatment programs address one substance at a time, but the strong bidirectional relationship between tobacco and cannabis suggests that simultaneous treatment may be more effective. Quitting one while continuing the other may undermine both efforts.

The numbers in context

Tobacco promotes cannabis dependence; cannabis promotes heavier tobacco use; cigarette smokers have accelerated cannabis relapse rates; both gateway and addiction vulnerability hypotheses supported

How the study worked

Narrative review of published studies examining co-morbid tobacco and cannabis use, focusing on neurobiological mechanisms, addiction theories, and treatment implications.

What this study cannot tell us

Narrative review that may not capture all relevant literature. Mechanisms proposed are largely theoretical. Few intervention studies had directly tested simultaneous cessation at the time of publication.

How to read the evidence

Comprehensive narrative review of neurobiological and behavioral evidence, though intervention data for simultaneous cessation was limited.

When this study was published

Published in 2015. Research on co-use treatment has continued to develop, and vaping has changed consumption patterns.

The bigger picture

The tobacco-cannabis co-use phenomenon challenges traditional approaches to addiction treatment. Emerging evidence suggests that quitting both simultaneously may yield benefits at both psychological and neurobiological levels, contrary to the conventional wisdom of tackling one addiction at a time.

Questions still open

Is simultaneous cessation of tobacco and cannabis more effective than sequential? Which neurobiological mechanism is most important for driving co-use? Would nicotine replacement therapy help cannabis cessation in co-users?

Common questions

Does smoking tobacco make it harder to quit cannabis?

Yes. This review found that cigarette smokers show increased and accelerated relapse rates when trying to quit cannabis. The shared neurobiological pathways and common route of administration create mutual reinforcement between the two habits.

Should you quit both at the same time?

Emerging evidence at the time suggested that simultaneous cessation may yield benefits at both psychological and neurobiological levels. The traditional approach of quitting one substance at a time may actually make it harder because continuing one substance can trigger relapse to the other.

Read the original research

A review of co-morbid tobacco and cannabis use disorders: possible mechanisms to explain high rates of co-use.

The American journal on addictions, 24(2), 105-116

View on PubMed ↗Publisher’s paper ↗

Citation

Rabin, Rachel Allison; George, Tony Peter. (2015). A review of co-morbid tobacco and cannabis use disorders: possible mechanisms to explain high rates of co-use.. The American journal on addictions, 24(2), 105-116. https://doi.org/10.1111/ajad.12186