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Chronic cannabis use triples mouth cancer risk

Alexey Kryvenko, medical expert
Last reviewed: 03.08.2025

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30 July 2025, 11:29

A recent study conducted by researchers at the University of California San Diego School of Medicine found that people with cannabis use disorder (CUD) were more than three times more likely to develop oral cancer over five years than people without the diagnosis. The findings highlight the potential long-term health risks associated with problematic cannabis use.

The study is published in the journal Preventive Medicine Reports.

As of 2022, 17.7 million people in the U.S. reported daily or near-daily cannabis use. While CUD requires a formal medical diagnosis and not all cannabis users develop the disorder, research suggests that up to 3 in 10 users may eventually develop CUD.

As cannabis becomes more accessible and socially acceptable, it is important to understand the potential health risks it poses. While many people consider cannabis to be safer than tobacco or alcohol, there are still many unknowns, especially when it comes to its impact on cancer risk. A new study aimed to understand the link between CUD and oral cancer, a disease for which tobacco smoking has long been considered a significant risk factor.

“Cannabis smoke contains many of the same carcinogenic compounds found in tobacco smoke that are damaging to oral epithelial tissue,” explains Raphael Cuomo, PhD, an associate professor of anesthesiology at the UC San Diego School of Medicine and a member of the Moors Cancer Center.
“These findings add to a growing body of evidence that chronic or problematic cannabis use may contribute to increased cancer risk in tissues exposed to combustion products.”

Key findings of the study:

The researchers analyzed electronic medical records of more than 45,000 patients, of whom 949 had been diagnosed with CUD.

After adjusting for age, sex, body mass index and tobacco status:

People with CUD were 325% more likely to develop oral cancer within 5 years than people without CUD.
Tobacco smokers with CUD were 624% more likely to have CUD than smokers without CUD.

Importantly, the association between CUD and oral cancer persisted even after accounting for tobacco smoking. Moreover, even among smokers, having CUD was associated with a higher risk, suggesting that there are additional risk factors beyond smoke inhalation.

One such factor may be THC (tetrahydrocannabinol), the active compound in cannabis that is known for its immunosuppressant properties, which could potentially increase the risk of cancer.

What does it mean:

Although further research is needed to fully elucidate the mechanism of the link between cannabis and oral cancer, the findings so far have practical implications for screening and prevention:

The importance of including oral health assessment in substance abuse treatment programmes is highlighted.
The findings could impact public health information campaigns and early detection methods for cancer in high-risk individuals.

The study reinforces the need for in-depth study of the long-term consequences of cannabis use and the need to consider oral health as part of substance use disorder counselling and treatment.