Does Cannabis Oil Cure Cancer? What the Evidence Shows

“Cannabis oil cures cancer” is one of the most searched health claims online, and this page once repeated it: that concentrated THC oil “works on many different forms of cancer in all stages” with “zero harmful side effects”, alongside films promoting the Gerson diet and Stanislaw Burzynski’s antineoplastons. People who search for this are often frightened and looking for hope, for themselves or someone they love. They deserve a straight answer. Here is what the research actually shows, what cannabinoids can genuinely help with, and which popular claims are false.

The short answer

• Does cannabis oil cure cancer? There is no reliable evidence that it does, in any type of cancer.
• Is there any research? Yes. Laboratory and animal studies are interesting, and a few small human trials are under way, but none has shown that cannabis treats cancer in people.
• Is it approved? The US National Cancer Institute (NCI) states that the FDA has not approved cannabis or cannabinoids as a cancer treatment (NCI, Cannabis and Cannabinoids PDQ).
• Can it help at all? Approved cannabinoid medicines can ease chemotherapy-related nausea and vomiting.

Why laboratory results are not a cure

Most of the “proof” shared online comes from studies of cancer cells in dishes or tumours in mice. One widely cited example is a 2007 Harvard study in which THC roughly halved the size of human lung cancer tumours implanted in mice; its lead researcher cautioned that “THC offers some promise, but we have a long way to go”. Lots of substances kill cancer cells in a dish, including bleach. The hard part is doing it safely inside a human body, at a dose people can tolerate, without harming healthy tissue.

Cancer Research UK puts it plainly: results from cells and animals “don’t necessarily hold true for people”, and “there simply isn't enough evidence to prove that cannabinoids” can treat cancer (Cancer Research UK). Our separate article explains why laboratory findings on cannabis and cancer are not proof of a cure.

What human studies have found so far

• The Tenerife pilot (2006). Nine people with recurrent glioblastoma, an aggressive brain tumour, had THC delivered directly into the tumour after surgery and radiotherapy had failed. Without a comparison group, the researchers could not tell whether it helped (British Journal of Cancer).
• Sativex with chemotherapy. In a small phase 1 study of 27 people with recurrent glioblastoma, 83% of those given the cannabis spray Sativex alongside temozolomide chemotherapy were alive after a year, against 44% on placebo. The study was designed to test safety and was too small to confirm a benefit.
• The ARISTOCRAT trial. A larger UK trial is now testing that combination properly. By January 2026 it had registered 94 patients at 17 NHS hospitals, with enrolment extended to April 2026 and results to follow (The Brain Tumour Charity).

In every one of these studies the cannabinoid was given alongside or after standard treatment, not instead of it.

What cannabinoids are approved for, and the risks

Two cannabinoid drugs, dronabinol and nabilone, are FDA-approved for chemotherapy-induced nausea and vomiting that has not responded to standard anti-sickness drugs. Neither is approved for pain. The NCI lists possible side effects of cannabis and cannabinoids including a fast heartbeat, low blood pressure, dizziness, drowsiness, depression, hallucinations and paranoia, and notes they may be addictive. Most importantly for people in treatment, a retrospective Israeli study found cannabis reduced the effect of immunotherapy (NCI).

Cancer Research UK adds specific warnings about cannabis oil: home-made oils can contain toxic solvent residues, their contents are often unknown, cannabinoids can interact with some chemotherapy drugs, and scammers target families by selling “cannabis oil” that never arrives.

Gerson, Burzynski and other “suppressed cures”

The original page also featured several documentaries. Here is what each promoted and what the record shows.

Run From the Cure tells the story of Rick Simpson, who made and gave away cannabis oil in Nova Scotia. In 2008 he was convicted of producing cannabis and possessing it for trafficking; the judge accepted he acted from sincere, altruistic motives and fined him $2,000, leaving questions of medical effectiveness to “Parliament and the scientific community” (R. v. Simpson, 2008 NSSC 57). The cures described in the film have not been confirmed in clinical studies.

(The video originally embedded here is no longer available on YouTube.)

Cancer is Curable NOW (trailer) and The Beautiful Truth and The Gerson Miracle promote natural therapies, especially the Gerson diet of juices and coffee enemas. The NCI reports that its 1947 and 1959 reviews of 60 of Max Gerson’s patients did not prove benefit, that no clinical trials have confirmed later claims, that the therapy is not FDA-approved, and that three deaths may be related to coffee enemas (NCI, Gerson Therapy PDQ).

Watch the video on YouTube (its owner does not allow it to be played on other sites).

The Cancer Report and The Rockefellers, the FDA and the Cancer Industry argue that natural cures were suppressed for profit. Neither offers evidence that a working cure exists; drug companies in fact sell cannabinoid medicines themselves.

(The video originally embedded here is no longer available on YouTube.)

Cancer is Serious Business presents Dr. Burzynski’s antineoplastons as a “non-toxic cure”. The NCI states that no randomised controlled trials of antineoplastons have been published, that they are not FDA-approved for any disease, and that side effects in trials have included seizures, confusion and brain swelling (NCI, Antineoplastons PDQ).

The page also carried a video on the 2007 lung cancer mouse study, an interview in which actor Tommy Chong said he would treat his prostate cancer with Rick Simpson’s oil (he was later also diagnosed with rectal cancer), a video titled “Proof Marijuana (THC) CURES Cancer!”, and a further film from its documentary list.

(The video originally embedded here is no longer available on YouTube.)

(The video originally embedded here is no longer available on YouTube.)

(The video originally embedded here is no longer available on YouTube.)

Common claims, checked

• “Chemotherapy kills 1 in 5 patients.” No source supports this. A Public Health England study of deaths within 30 days of treatment found fewer than 1 in 100 for breast cancer and about 3 in 100 for lung cancer when the aim was cure, and about 7 and 10 in 100 among people treated for advanced disease, counting deaths from any cause, including the cancer itself (Cancer Research UK).
• “Untreated patients live four times longer.” This is usually attributed to the physicist Hardin Jones, but the fact-checkers at Correctiv found that his 1956 essay reviewed death rates from 1911 to 1943, before modern chemotherapy, and contains no such figures (Correctiv).
• “Alternative treatment is safer.” A Yale study matched 280 patients who used only alternative medicine with 560 who had conventional treatment. The alternative-only group was about 2.5 times as likely to die over five and a half years, and about six times for breast cancer (Yale School of Medicine).
• “The government patented cannabis because it knows it cures cancer.” US patent 6,630,507 covers cannabinoids as antioxidant “neuroprotectants”, for conditions such as stroke, not cancer. Who actually lobbied on marijuana laws is covered in this look at special-interest lobbying.

If you or someone you love has cancer

1. Talk to your cancer team before taking anything, including cannabis products, supplements or special diets. Some interact with treatment.
2. Ask about clinical trials. They give access to new treatments, including cannabinoid trials, in a monitored setting.
3. Ask about symptom relief. If nausea, pain or appetite are the problem, there are approved options, including cannabinoid medicines in some cases.
4. Be wary of anyone selling a cure, especially online, for cash, with testimonials instead of trial results.

Wanting more control and more hope during cancer treatment is completely understandable. The safest way to get both is to use complementary approaches alongside proven treatment, never in place of it.

Sources: NCI: Cannabis and Cannabinoids PDQ (patient version); Cancer Research UK: Cannabis, cannabinoids and cancer, the evidence so far; Guzmán et al., British Journal of Cancer (2006); The Brain Tumour Charity: ARISTOCRAT trial; NCI: Gerson Therapy PDQ; NCI: Antineoplastons PDQ; R. v. Simpson, 2008 NSSC 57; Cancer Research UK on 30-day mortality (2016); Correctiv (2018); Yale School of Medicine.

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• Cannabis and Cancer Research: Laboratory Findings Are Not Proof of a Cure
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