A recent study conducted by researchers at the University of California San Diego has revealed that individuals diagnosed with cannabis use disorder are three times more likely to develop oral cancer compared to those without the disorder. This ground-breaking finding, published in July 2025, raises significant concerns for public health officials in Thailand, where the decriminalization of cannabis has triggered a surge in cannabis consumption, especially among young adults and recreational users.
Oral cancer—affecting regions such as the mouth, gums, and throat—remains a major health challenge both globally and in Thailand, where oral cavity cancers account for approximately 8–10% of all cancer-related deaths according to data from the National Cancer Institute of Thailand. Historically, tobacco and alcohol have been the leading risk factors for oral cancer, but the emergence of cannabis use as a significant factor adds new complexity to prevention efforts in the country. The study from UC San Diego, as reported by today.ucsd.edu, analyzed electronic health records from hundreds of thousands of patients, finding a robust and statistically significant link between cannabis use disorder—a condition characterized by frequent and uncontrollable cannabis consumption—and an elevated risk of oral cancer.
The research methods drew upon large-scale patient record data, controlling for known confounders such as tobacco and alcohol use. This is noteworthy for Thailand, as the prevalence of tobacco use among cannabis users has historically made it difficult to isolate cannabis’ direct risks, but this study suggests a strong association even when accounting for these factors. The lead author—a clinical epidemiologist at UC San Diego—highlighted, “Our results strongly suggest that chronic, problematic cannabis use is an independent risk factor for oral malignancies, separate from the risks already posed by tobacco and alcohol.”
Health experts in Thailand are watching these developments closely. A senior specialist at the Ministry of Public Health’s Cancer Division commented that, “This research serves as an early warning for Thai society. With the rapid liberalization of cannabis-related regulations, we must be vigilant and proactive in preventing a potential increase in oral cancer cases linked to cannabis use.” Thai dentists and oncologists have in recent years reported anecdotal observations of oral lesions and suspicious tissue changes in patients who use cannabis regularly, but up until now, scientific evidence on cannabis’ direct carcinogenic potential in the oral cavity had been limited.
Thailand’s cultural connection to medicinal cannabis is deep-rooted, stretching back to traditional herbal medicine practices in various regions. However, the current wave of legalization since 2022—coupled with growing recreational interest, especially among teenagers and young adults—demands a new public health approach. According to a 2024 survey by the Department of Medical Services, up to 17% of secondary school students in Bangkok have experimented with cannabis, and the number of cannabis-related clinic visits has increased nationwide.
International research supports the UC San Diego findings. Publications indexed on PubMed, such as a systematic review in “Oral Oncology” (2023), have also suggested a possible link between long-term cannabis use and oral cancer, theorizing mechanisms such as chronic inflammation, exposure to carcinogenic smoke, and immune system suppression as possible contributing factors (pubmed.ncbi.nlm.nih.gov/37324517/). However, this new study provides unprecedented clarity due to its large sample size and robust controls.
The implications for Thai policy are substantial. As cannabis-infused products and vaping devices become widely available in cities like Bangkok, Chiang Mai, and Pattaya, questions arise about regulation, youth access, and the adequacy of health warnings. Officials at Thailand’s Food and Drug Administration have expressed concern that existing labeling requirements on cannabis products may not sufficiently inform consumers about cancer risks. In response to international findings, the Dental Council of Thailand has called for the inclusion of oral cancer risk information in all cannabis product health warnings.
Culturally, cannabis is sometimes seen as a low-risk alternative to alcohol or tobacco, with some Thai communities incorporating it into traditional cuisine or medicine. However, as this new research makes clear, patterns of frequent, heavy use—particularly in the form of smoking or vaping—can have serious ramifications. A senior lecturer in public health at a leading Thai university observed, “It is vital that our health education campaigns catch up to the science. We should not repeat the mistakes made with tobacco in the 20th century, waiting for cases to surge before acting.”
Looking forward, Thai researchers and public health agencies are expected to initiate their own studies into cannabis use and oral cancer rates, especially given the country’s unique patterns of consumption and genetic predisposition. Local NGOs, including those focused on youth health and cancer prevention, are launching new awareness campaigns targeting schools and universities.
There are practical steps Thai readers can take in light of this research. First, those who use cannabis—especially through smoking or vaping—are encouraged to seek regular dental checkups and promptly report any persistent mouth sores, lumps, or unusual changes to dental professionals. Second, families and educators should be informed about the new risks so they can provide accurate guidance to youth. Third, policymakers and business operators involved in the cannabis trade should ensure that health risk information is prominently displayed and easy to understand.
In conclusion, the recently published UC San Diego study has sent a clear message to both the medical and general public in Thailand: cannabis is not risk-free. As Thailand embarks on one of the world’s most ambitious legalization projects, it must balance economic opportunity with health protection, learning from global research and investing in public education, prevention, and early detection programs.
Sources: today.ucsd.edu, National Cancer Institute of Thailand, PubMed – Oral Oncology, Department of Medical Services, Thailand