New research suggests that problematic cannabis use might be linked to the development of noncancerous tumors in the salivary glands, which are responsible for producing saliva in the mouth.

Problematic cannabis use was linked to an up to five-fold risk of developing these benign growths when compared with the general population, according to research published recently in a leading medical journal.

“Cannabis smoke contains many of the same carcinogens and irritants as tobacco smoke, so it is biologically plausible that long-term use could trigger changes in salivary gland cells,” Dr. Abie Mendelsohn, a laryngologist at the Los Angeles Center for Ear, Nose, Throat and Allergy, who was not involved with the study, told The Epoch Times.

A 20-Year Study

The new research, published in JAMA on July 17, found that 0.08 percent of people with cannabis use disorder developed benign salivary gland tumors, compared to just 0.02 percent of those without the disorder.

The retrospective cohort study, conducted from Jan. 24, 2005, to Jan. 24, 2025, analyzed anonymized data from 66 U.S.-based health care organizations through the TriNetX US Collaborative Network. Researchers examined records from nearly 184,000 people, aged 18 and older, with cannabis use disorder and compared them to more than 6.2 million people without the condition.

In people with cannabis use disorder, researchers estimated that the relative risk of developing benign major salivary gland tumors was about five times that of those without the disorder.

Cannabis use disorder was defined as cannabis dependence with associated psychosocial symptoms such as impaired social or occupational functioning—representing the most severe form of problematic marijuana use rather than casual consumption.

Researchers controlled for key variables, including age, race, ethnicity, tobacco use, nicotine use disorder, and history of radiation exposure to isolate the cannabis effect.

The study specifically focused on benign tumors in salivary glands. These noncancerous growths, while not life-threatening, can cause discomfort, swelling, and in some cases, functional problems, such as difficulty opening the mouth widely and numbness in part of the face.

Biological Mechanism Unclear

While the association appears robust, researchers emphasize the study’s limitations.

“However, this association is newly observed and not yet proven to be causal,” Mendelsohn noted.

The study didn’t examine tissue samples or track detailed information regarding consumption patterns, dosage, or delivery methods. Scientists believe the active compounds in cannabis could influence cell growth in salivary glands, potentially promoting tumor development, but the exact biological mechanism remains unclear.

Dr. Christopher Vanison, residency program director of otolaryngology and head and neck cancer surgeon at Stony Brook Medicine, noted that heat and smoke can cause cellular changes within salivary gland ducts, leading to tumor formation.

“We know that cigarette smoking is strongly associated with development of a type of benign salivary gland tumor called a Warthin tumor,” said Vanison, who was not involved in the research. “Those who smoke more heavily and for longer periods of time are more likely to develop these tumors.”

Researchers pointed out that previous research already found that smoking cigarettes was also connected to these tumors, possibly because smoke can cause changes and damage to the cells in the glands.

The study authors noted that more research is needed, particularly long-term studies that track people and gather detailed information on their cannabis use and consumption methods. This will help confirm if cannabis contributes to tumor development and clarify the underlying biological mechanisms.

If further research does establish a causative link, Mendelsohn noted, it could add to the list of health risks linked with heavy cannabis use. He noted previous research involving more than 116,000 participants that found smoking cannabis heavily is linked to a significantly increased risk of developing head and neck cancers, including cancers of the oral cavity and throat.

Warning Signs

Certain symptoms and signs can indicate whether a salivary gland tumor is likely to be benign or malignant.

Painless swelling in the area of a salivary gland is the most common presentation for both benign and early malignant tumors, Mendelsohn said.

“If the tumor grows large, it may cause a visible bulge and can lead to discomfort or a feeling of tightness,” he said. “Difficulty opening the mouth fully or trouble swallowing can occur if a tumor, especially in the parotid deep lobe or minor salivary glands of the throat, is impinging on structures in the mouth or throat.”

More worrisome signs include persistent pain in the area of the gland, numbness, or muscle weakness in part of the face, according to Mendelsohn.

For example, he said, if a parotid tumor causes weakness in half of the face or an inability to smile or close an eye on the affected side, the tumor might be affecting the facial nerve.

Such symptoms are red flags that often point to a malignant tumor rather than a benign one, he said.

“Likewise, numbness or tingling in the face over the tumor, or skin fixation/ulceration, are signs that warrant prompt evaluation,” Mendelsohn said.