Cannabis addiction triples oral cancer risk in just five years, study finds

A new California study reveals that cannabis use disorder is linked to a threefold rise in oral cancer risk, challenging the belief that marijuana is a 'safe' drug

Cannabis is legal in many parts of the world. But that does not mean it is without risk. A new study titled ‘Cannabis use disorder and five-year risk of oral cancer in a multicenter clinical cohort’, published in Preventive Medicine Reports, has found that individuals diagnosed with cannabis use disorder (CUD) face more than triple the risk of developing oral cancer, specifically cancers of the lip or tongue, within just five years.

 

Drawing on the medical records of over 45,000 patients from six University of California medical centres, the research raises important concerns about the long-term consequences of heavy and problematic cannabis use.

 

What is cannabis use disorder?

Cannabis use disorder (CUD) is a clinical diagnosis for problematic cannabis use that disrupts daily life. It does not just mean occasional recreational smoking, it reflects frequent consumption that can lead to dependence.

 

Previous studies have shown that people smoking about 14 or more joints a week often meet the criteria. In this study, CUD was identified through medical records with formal diagnostic codes, making it a reliable marker for heavy and sustained cannabis exposure.

Link between CUD and oral cancer

The study followed 45,129 adults who had no oral cancer at the start. Over five years, 949 developed CUD. Of these, 0.74 per cent went on to develop oral cancer, compared to just 0.23 per cent among those without CUD. After adjusting for factors like age, sex, body mass index, and smoking status, CUD patients still had a 3.25 times higher risk of oral cancer. Among smokers, the risk shot up even more, those with both CUD and a smoking history had a six-fold increased risk.

How cannabis may raise oral cancer risk

Cannabis smoke contains many of the same cancer-causing chemicals as tobacco, polycyclic aromatic hydrocarbons, benzo[a]pyrene, and phenols. These toxins can damage the cells lining the mouth and respiratory tract, causing precancerous changes even without tobacco use. Laboratory studies show cannabis smoke can damage DNA, trigger mutations, and suppress immune defences, especially in tissues directly exposed to the smoke, like the mouth, lips, and lungs.

Doctors urge oral checks for cannabis users

CUD is on the rise. Yet many heavy users do not see their habit as dangerous, say experts. This study challenges that perception, showing measurable cancer risk over a relatively short period.

 

Researchers of the study warn that CUD may also be linked to other overlapping social and behavioural risk factors, including tobacco use, alcohol consumption, and reduced engagement in preventive healthcare, which can further raise cancer risk.

 

The report authors have suggested that doctors should consider regular oral health checks for patients with CUD, especially if they have other risks like tobacco or alcohol use. Detecting oral cancers early can significantly improve treatment outcomes. This is particularly important because many people don’t recognise that their cannabis use could be a red flag for health. 

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This content is for informational purposes only and is not a substitute for professional medical advice.