Cannabis and Liver Cancer: What the Research Says (2026)

By James Buddsey · Updated October 16, 2026

Cannabis has not been shown to treat liver cancer in people: cannabinoids slowed hepatocellular carcinoma cells in lab dishes and in mice, but no human trial has tested them against the disease. Some large hospital-database studies found lower rates of liver cancer among cannabis users, which shows an association, not a cause. CBD can also raise liver enzymes, which matters for anyone with liver disease.

This page replaces a 2020 post that described a Tehran University study as proof that cannabis fights liver cancer and claimed marijuana has “no known side effects.” Neither claim holds up. Below is what that study actually found, what other research shows, and what it means for patients as of October 2026. It is part of our overview of cannabis and cancer research.

Evidence at a Glance

What the Tehran Study Found

The study behind the original headline came from the Faculty of Pharmacy at Tehran University of Medical Sciences and was published in Toxicology Mechanisms and Methods in 2013, years before our old post ran. The researchers tested two lab-made compounds, CB65 (which targets the CB2 receptor) and ACEA (which targets CB1), on HepG2, a human liver cancer cell line. At higher concentrations, both compounds reduced cell viability and invasion and lowered two enzymes, MMP-2 and MMP-9, that tumors use to spread.

That is a useful early signal, but it is a dish of cells. Neither compound is cannabis, neither is sold as a medicine, and nothing was tested in animals or people.

Other Lab and Animal Research

THC and autophagy (2011 and 2013)

A team at Alcalá University and Complutense University in Madrid found that THC and a CB2-selective compound, JWH-015, reduced the viability of two human liver cancer cell lines by triggering autophagy, a process in which cells break down their own parts. Both compounds slowed tumors implanted under the skin of mice and also reduced tumor growth and fluid buildup in a model where tumors grew in the liver. A follow-up paper from the same group linked the effect to a protein called PPARγ.

CBD

A 2025 review in Cancer Cell International found 16 relevant studies of CBD in liver cancer. In lab models, CBD triggered several kinds of cancer cell death and made cells more sensitive to sorafenib and cabozantinib, two approved liver cancer drugs. The authors stressed that clinical studies are limited and that dosing, absorption and possible liver toxicity all need work.

Why mouse results often fail in people

The National Cancer Institute’s PDQ summary on cannabis notes that anticancer effects vary between models and that doses used in animals may not translate to people. Many compounds that shrink tumors in mice never work in human trials.

Do Cannabis Users Get Less Liver Cancer?

Two studies using the U.S. National Inpatient Sample, a database of hospital discharge records, have drawn attention:

• Among more than 101 million patient records from 2002 to 2014, people coded with cannabis abuse were 55% less likely to have a liver cancer diagnosis after adjustment for other factors.
• Among about 320,000 patients with a history of heavy drinking, cannabis users had lower odds of every stage of alcohol-related liver disease, including liver cancer.

These findings do not show that cannabis prevents liver cancer. Billing codes miss a lot of cannabis use, cannabis users in the first study were 14 years younger on average, and people with serious liver disease may stop using cannabis or be told to. The authors of both studies called for prospective research. A 2022 review of recreational drugs and liver cancer called cannabis’s effect on liver scarring in chronic hepatitis “controversial” on existing data, while noting that cigarette smoking is a clear liver cancer risk factor. For hepatitis specifically, see our page on cannabis and hepatitis.

Is There Any Human Trial?

No published randomized trial has tested cannabis, THC or CBD as a treatment for liver cancer. The National Academies’ 2017 review found insufficient evidence that cannabinoids treat cancers. The American Society of Clinical Oncology’s 2024 guideline advises against using cannabis to treat cancer outside a clinical trial. Patients interested in experimental options can search NCI’s clinical trials database.

Where cannabinoids do have proven value is symptom control. The FDA has approved dronabinol and nabilone for chemotherapy-related nausea and vomiting that other drugs have not controlled.

Risks and Side Effects for People With Liver Cancer

• Liver enzymes. In an FDA-run randomized trial in healthy adults, CBD at 5 mg/kg per day for four weeks raised liver enzymes above three times normal in 5.6% of people, versus none on placebo. FDA also lists liver injury as a known CBD risk. Most people with liver cancer also have cirrhosis or hepatitis, so the margin for extra liver stress is small.
• Drug interactions. CBD and THC are processed by liver enzymes that also handle many cancer drugs. NCI’s PDQ notes CBD can inhibit these enzymes, which may change drug levels.
• Smoking. Smoke of any kind harms the lungs and adds to overall cancer risk. If a doctor approves cannabis, non-smoked forms are preferable.
• Brain effects. Advanced liver disease can cause confusion (hepatic encephalopathy). THC’s sedating and cognitive effects can make that harder to recognize and manage.

Talk to Your Doctor

Tell your oncologist and hepatologist about any cannabis or CBD product before you use it, including dose and form. Ask whether it could interact with your treatment, if your liver function allows it, and whether a clinical trial fits your situation. Never replace or delay standard liver cancer treatment, such as surgery, ablation, transplant evaluation or systemic therapy, with cannabis. More health topics are in our cannabis research section.

Cannabis and Liver Cancer FAQ

For adults 21+ in legal states. General information, not medical advice. Talk to a doctor before using cannabis for a health condition.