As cannabis use becomes more widespread, understanding its potential health implications, particularly concerning oral cancer, is important. This article explores the current scientific understanding of cannabis use and its connection to oral cancer. It examines how cannabis might impact oral health, reviews relevant research, and outlines other established risk factors for this type of cancer, also providing information on recognizing potential signs for early detection.
What is Oral Cancer?
Oral cancer refers to cancers affecting the inside of the mouth and the back of the throat. It commonly develops on the lips, tongue, gums, inner cheeks, and the roof or floor of the mouth. 90% of oral cancers are squamous cell carcinomas, originating from the flat cells lining these areas.
Oral cancer represents about 3% of all diagnosed cancers in the United States, with an estimated 59,660 new cases in 2025. This cancer is more common in individuals over 40 and affects men more frequently than women. If left untreated, oral cancer can spread to other areas of the head and neck.
How Cannabis Affects Oral Health
Smoking cannabis can lead to several general effects on oral health. The smoke itself can cause irritation to the soft tissues inside the mouth, which can contribute to inflammation.
A common side effect reported by cannabis users is xerostomia, or dry mouth, due to reduced saliva production. Saliva washes away food particles and bacteria, so dry mouth increases the risk of tooth decay and gum disease. Long-term cannabis use has also been associated with higher rates of periodontal disease, an infection of the tissues supporting the teeth.
The act of smoking cannabis can lead to teeth discoloration and staining. Some research also suggests that cannabis use might alter the oral microbiome, increasing certain pathogenic yeasts like Candida albicans, which can lead to oral candidiasis. This immunosuppressive effect can also impair the body’s ability to fight oral infections.
Research on Cannabis and Oral Cancer
Research into the direct link between smoking cannabis and oral cancer has been complex. Early studies struggled to isolate cannabis effects from established risk factors like tobacco and alcohol use, making definitive conclusions difficult.
More recent research clarifies this association. A University of California San Diego study, following over 45,000 patients, found that individuals diagnosed with cannabis use disorder (CUD) were 3.25 times more likely to develop oral cancer within five years compared to those without CUD. This elevated risk persisted even after accounting for age, sex, body mass index, and tobacco smoking status.
This suggests mechanisms beyond simple smoke exposure, as the risk remained significant even among tobacco smokers with CUD. Cannabis smoke contains hundreds of polycyclic aromatic hydrocarbons (PAHs), benzene, and ammonia. Many are known carcinogens also found in tobacco. These compounds can directly damage DNA in oral epithelial cells, contributing to cancer development.
Other Risk Factors for Oral Cancer
While the understanding of cannabis’s role in oral cancer is evolving, several other factors are well-established as significant contributors to the disease. Tobacco use, including cigarettes, cigars, pipes, and smokeless products, is a primary risk factor for oral cancer.
Excessive alcohol consumption also raises the risk of oral cancer. The risk is particularly elevated for individuals who use both tobacco and alcohol, as these substances can act synergistically to increase cancer risk by up to 30 times. Alcohol can dry out oral tissues, making them more vulnerable to carcinogens.
Infection with human papillomavirus (HPV), particularly type 16, is another recognized risk factor, especially for oropharyngeal cancers. Prolonged sun exposure without protection is linked to lip cancer. Other factors include a poor diet lacking fruits and vegetables, and inadequate oral hygiene.
Recognizing Potential Signs
Recognizing oral cancer signs early is important for improving outcomes. Common symptoms include a persistent sore or irritation in the mouth that does not heal within two weeks. Red or white patches inside the mouth, which may be flat or slightly raised, also warrant attention. White patches are known as leukoplakia, red patches as erythroplakia, and combined red and white as erythroleukoplakia.
Other signs include a lump or thickening in the mouth or on the lip, unexplained numbness, pain, or tenderness in the mouth or face. Difficulty chewing, swallowing, or speaking, along with a persistent sore throat or voice changes, could also indicate a concern. Regular dental check-ups are important, as dentists often perform oral cancer screenings during routine visits. Any suspicious symptoms lasting longer than two weeks should prompt a consultation with a healthcare professional.