Cannabis does not treat or cure leukemia: THC and CBD kill leukemia cells in lab dishes and slowed some blood cancers in mice, but no human trial has shown that cannabis treats leukemia. The main human research in blood cancers is a small study of CBD to prevent graft-versus-host disease after a stem cell transplant. For people in treatment, cannabinoids may help chemotherapy nausea, but they carry real risks for patients with weakened immune systems.
Leukemia is a cancer of the blood-forming cells, and its treatment often involves intensive chemotherapy and sometimes a bone marrow or stem cell transplant. Those treatments leave patients highly vulnerable to infection and drug interactions, which shapes how cannabis should be viewed. This page summarizes the research as of October 2026 and is part of our overview of cannabis and cancer.
Evidence at a Glance
| Claim | Evidence level | Source |
|---|---|---|
| THC and CBD kill leukemia and lymphoma cells | Preclinical only (cells and mice) | McKallip 2002, Scott 2017 |
| Cannabis treats leukemia in people | No human evidence | ASCO 2024 |
| CBD lowers graft-versus-host disease after transplant | Limited (one phase II study vs. historical controls) | Yeshurun 2015 |
| Cannabinoids ease chemotherapy nausea and vomiting | Strong for refractory nausea; FDA-approved drugs | FDA, Cochrane 2015 |
| Parental cannabis use and childhood leukemia | Insufficient evidence either way | NASEM 2017 |
What Lab Studies Found About Cannabis and Leukemia
White blood cells, including leukemia cells, carry the CB2 cannabinoid receptor, which is one reason researchers have looked at cannabinoids in blood cancers.
- THC and CB2 receptors (2002). A University of South Carolina team found that THC triggered cell death in mouse lymphoma cells and in human leukemia and lymphoma cell lines, partly through CB2. THC also reduced tumor load and improved survival in mice with lymphoma, and reduced viability of cells taken from patients with acute lymphoblastic leukemia.
- Combining cannabinoids with chemotherapy (2017). London researchers reported that pairs of cannabinoids worked better together against leukemia cells and made the cells more sensitive to standard chemotherapy drugs. The order mattered: cannabinoids given after chemotherapy worked better than before.
- A negative early result (1975). One of the first cannabinoid cancer studies found that oral THC did not extend the lives of mice with L1210 leukemia, even though it slowed lung tumors in the same paper.
These studies are worth following, but they used cell lines and mice. The doses, delivery and immune effects in a human patient are different. NCI’s PDQ summary also notes that THC can suppress immune responses, which in some mouse models allowed tumors to grow faster.
Is There Human Evidence That Cannabis Treats Leukemia?
No. There are no controlled human trials of cannabis or cannabinoids as a leukemia treatment. A widely shared 2013 case report described a 14-year-old with treatment-resistant acute lymphoblastic leukemia whose family gave the patient cannabis extract after standard treatment failed, with the authors reporting dose-related changes in blood counts. A single uncontrolled case cannot show cause and effect. The National Academies found insufficient evidence that cannabinoids treat any cancer, and ASCO’s 2024 guideline advises against using cannabis as a cancer treatment outside a clinical trial. Leukemia treatment has improved dramatically, particularly for children with ALL, and delaying it is dangerous.
CBD and Graft-Versus-Host Disease After Transplant
The most interesting human research in this area is not about killing cancer cells. Graft-versus-host disease (GVHD) happens when donor immune cells from a stem cell transplant attack the patient’s body. Because CBD has anti-inflammatory and immune-suppressing effects, Israeli researchers ran a phase II study of 48 adults, 79% of whom had acute leukemia or myelodysplastic syndrome. They took 300 mg of CBD a day from a week before transplant to day 30, on top of standard GVHD prevention.
None developed acute GVHD while taking CBD, and the rate of moderate-to-severe acute GVHD by day 100 was 12.1%. Compared with 101 earlier patients, the risk of grade II to IV GVHD was about 70% lower. The study had no randomized control group, and the authors called for a proper randomized trial. This is a transplant medication question for the transplant team, not a reason to self-treat with store-bought CBD.
Symptom Relief During Leukemia Treatment
- Nausea and vomiting: The FDA approved dronabinol and nabilone for chemotherapy nausea and vomiting that standard antiemetics have not controlled. A Cochrane review found cannabis-based medicines may help refractory nausea, though the trials are dated. ASCO supports them only as an add-on to standard antiemetics.
- Appetite: Trials in cancer patients have been mostly negative; in one large trial megestrol outperformed dronabinol.
- Pain: A 2023 Cochrane review found cannabinoids did not beat placebo for opioid-resistant cancer pain.
Special Risks for People With Leukemia
- Infection. Leukemia and its treatment can leave patients with very low white blood cell counts. Physicians have raised concerns about Aspergillus mold spores in cannabis, which can cause serious lung infections in people with weakened immune systems. Smoking or vaporizing raw plant material is a particular concern.
- Drug interactions. CBD inhibits cytochrome P450 liver enzymes. Many leukemia drugs, antifungals and transplant immunosuppressants such as cyclosporine and tacrolimus are processed by these enzymes, so levels can shift. NCI warns that concentrated CBD oils could raise toxicity or reduce effectiveness.
- Immune effects. THC can dampen immune responses. That may be unwanted when the immune system is part of how treatment works, including after transplant.
- Bleeding and falls. Low platelet counts raise bleeding risk, and cannabis can cause dizziness and low blood pressure.
- Children. There is no evidence supporting cannabis for childhood leukemia, and THC carries particular risks for the developing brain, according to NIDA.
Does Cannabis Cause Leukemia?
There is no good evidence that adult cannabis use causes leukemia. The National Academies found insufficient evidence on whether a parent’s cannabis use raises a child’s risk of acute myeloid leukemia, so that question remains open.
Talk to Your Doctor
Before using any cannabis product during leukemia treatment, talk to your hematologist-oncologist or transplant team. Ask whether a prescription cannabinoid would be safer for nausea, whether CBD interacts with your medicines, and whether your blood counts make inhaled products unsafe. If you are interested in cannabinoid research, ask about clinical trials or search the NCI trial database. For background on the compounds themselves, see our explainers on THC and other cannabinoids and CBD benefits and hype.
Leukemia and Marijuana FAQ
Can cannabis oil cure leukemia?
No. Cannabinoids killed leukemia cells in lab studies, but no human trial has shown that cannabis oil treats leukemia. A single widely shared case report is not evidence of a cure.
Does CBD help with leukemia?
Not as a cancer treatment. A small Israeli study found that CBD may lower graft-versus-host disease after stem cell transplant, but it needs a randomized trial to confirm.
Is it safe to smoke weed with leukemia?
It is risky. Smoked cannabis can carry mold spores that cause serious infections in people with low white blood cell counts, and smoke irritates the lungs. Talk to your care team first.
Can cannabis help with nausea from leukemia chemotherapy?
Prescription cannabinoids such as dronabinol and nabilone are FDA-approved for chemotherapy nausea that standard drugs have not controlled.
Does marijuana interact with leukemia drugs?
It can. CBD affects liver enzymes that process many chemotherapy drugs, antifungals and transplant medicines. Tell your oncologist and pharmacist what you use.
For adults 21+ in legal states. General information, not medical advice. Talk to a doctor before using cannabis for a health condition.
