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CBD and cancer

CBD is not a cancer treatment. An Australian trial in advanced cancer found CBD oil did not improve symptoms beyond palliative care alone.

Facts checked 13 November 20265 min readHow we research
Trials show no benefit

An Australian placebo-controlled trial of CBD oil titrated from 50 to 600 mg a day found no improvement in symptom burden in advanced cancer; there is no clinical trial evidence that CBD treats cancer itself.

How we grade evidence

CBD is not a cancer treatment. No clinical trial has shown that it cures, shrinks or slows cancer in people. For symptom relief, an Australian placebo-controlled trial in people with advanced cancer found that CBD oil did no better than specialist palliative care alone.

What the research shows

Does CBD treat cancer itself?

The claim that CBD fights cancer comes from laboratory studies on cells and from animal studies. Results at that stage often fail to carry over to people. See how we grade the evidence.

A 2021 review of the clinical data and case reports found no strong clinical trial data confirming that CBD has an anticancer benefit.1 Cancer Research UK reached the same conclusion in its summary of the evidence on cannabis, cannabinoids and cancer.2

Does CBD ease symptoms in advanced cancer?

Australian researchers have run the best trial on this question, known as MedCan1-CBD.3

  • Who: adults with advanced cancer receiving palliative care, at several Australian centres. Sources report 142 or 144 people randomised, and 121 reached the main analysis at day 14.34
  • What: CBD oil or matching placebo for 28 days, on top of standard palliative care. The dose started at 50 mg a day and could be raised as high as 600 mg a day. The median dose people settled on was 400 mg a day.4
  • Measured: total symptom distress on the Edmonton Symptom Assessment Scale, a questionnaire that scores a range of common symptoms.3
  • Result: symptom scores fell by 3.0 points with CBD and 6.2 points with placebo, a difference that was not statistically significant. A meaningful improvement was reached by about 45% of people on CBD and 59% on placebo.4
  • Other outcomes: no significant differences were reported in quality of life, depression or anxiety. New or worsening breathlessness was more common with CBD (8 people against 2).4

The authors concluded that CBD oil “did not add value to the reduction in symptom distress provided by specialist palliative care alone”.4

What about products that contain THC?

The same research group then tested an oil containing THC and CBD in equal parts. THC is the compound in cannabis that causes a high. In 144 people with advanced cancer, the THC:CBD oil was no better than palliative care alone for total symptom burden. There was a small benefit for pain, with more side effects, mainly drowsiness.5

A third trial, MedCan-3, is testing an oil that is mostly CBD with a little THC (a ratio of 1 part THC to 20 parts CBD). It was reported as still under way in October 2025 and we found no results as of November 2026.6

For cancer pain, a 2023 Cochrane review covered 14 trials and 1,823 adults. Those trials tested nabiximols (a THC and CBD mouth spray) and THC-like medicines, not CBD alone.7

Nausea and vomiting from chemotherapy is a separate question with its own evidence. See CBD for chemotherapy nausea.

What doses were tested

In the Australian palliative care trial, people adjusted their own dose between 50 and 600 mg a day, and the median was 400 mg a day.4 That is well above the 150 mg a day limit for pharmacist-only (Schedule 3) CBD in Australia.8 Even at those doses, CBD did not improve symptoms.

No dose of CBD has been shown to treat cancer in people.1

What Australian medical bodies say

  • RACGP. The Royal Australian College of General Practitioners says the effectiveness of medicinal cannabis in palliative care is unclear. It describes the overall evidence base as “limited and inconclusive”.9
  • TGA. The Therapeutic Goods Administration’s guidance says medicinal cannabis should be considered only when registered medicines have been tried and failed, and that treatment should be stopped if benefit has not been shown.10

See what Australian medical bodies say about CBD.

Risks to know about

  • Interactions with cancer care. CBD blocks several liver enzymes that the body uses to process medicines, and it blocks a transporter that moves medicines around the body.11 In one interaction it raised blood levels of the medicine everolimus about 2.5-fold.11 Your oncologist or cancer pharmacist should check anything you plan to take. See CBD drug interactions.
  • Liver. CBD can raise liver enzymes, and the effect is related to dose.11 Ask your team whether that matters for your treatment. See CBD and the liver.
  • Sedation. CBD adds to the drowsiness caused by opioids, benzodiazepines and other sedating medicines.11
  • Products containing THC. In the THC:CBD trial, drowsiness was the main added side effect.5 The TGA’s guidance says patients should be advised they are not able to drive while being treated with medicinal cannabis.10
  • Replacing treatment. No trial supports using CBD in place of cancer treatment. See CBD myths and misleading claims.

If you are considering it

  • Tell your oncologist, palliative care team or cancer pharmacist before you take anything.
  • Bring the exact product details if you already have one, including whether it contains THC.
  • Questions worth asking: Could this interact with my treatment? Do I need extra liver blood tests? What symptom are we trying to improve, and is there a treatment with better evidence for it? How will we judge whether it is working?

Footnotes

  1. Review of clinical data and case reports on cannabidiol as an anticancer treatment, 2021. https://pubmed.ncbi.nlm.nih.gov/34370591/ ↩ ↩2

  2. Cancer Research UK. Cannabis, cannabinoids and cancer: the evidence so far, 2021. https://news.cancerresearchuk.org/2021/09/01/cannabis-cannabinoids-and-cancer-the-evidence-so-far/ ↩

  3. Hardy J, et al. Phase IIb randomized, placebo-controlled, dose-escalating, double-blind study of cannabidiol oil for the relief of symptoms in advanced cancer (MedCan1-CBD). Journal of Clinical Oncology, 2023. https://pubmed.ncbi.nlm.nih.gov/36409969/ ↩ ↩2 ↩3

  4. The ASCO Post. Does CBD oil improve symptom distress in patients with advanced cancer receiving palliative care? December 2022. https://ascopost.com/news/december-2022/does-cbd-oil-improve-symptom-distress-in-patients-with-advanced-cancer-receiving-palliative-care ↩ ↩2 ↩3 ↩4 ↩5 ↩6

  5. Hardy J, et al. Randomised trial of THC:CBD 1:1 oil for symptom burden in advanced cancer. Supportive Care in Cancer, 2025. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12289739/ ↩ ↩2

  6. Mater Research. Cannabis is of limited benefit as a cancer painkiller, study finds, October 2025. https://www.materresearch.org.au/news-publications/news/2025/october/cannabis-is-of-limited-benefit-as-a-cancer-painkiller-study-finds ↩

  7. Häuser W, et al. Cannabis-based medicines and medical cannabis for adults with cancer pain. Cochrane Database of Systematic Reviews, 2023. https://cochranelibrary.com/cdsr/doi/10.1002/14651858.CD014915.pub2/information ↩

  8. Therapeutic Goods Administration. Final decision on down-scheduling of low-dose cannabidiol, 2020. https://tga.gov.au/node/284859 ↩

  9. Royal Australian College of General Practitioners. Position statement: use of medicinal cannabis products in Australia (2019 update). https://www.racgp.org.au/advocacy/position-statements/view-all-position-statements/clinical-and-practice-management/medical-cannabis ↩

  10. Therapeutic Goods Administration. Guidance for the use of medicinal cannabis in Australia: overview. https://www.tga.gov.au/resources/resource/guidance/guidance-use-medicinal-cannabis-australia-overview ↩ ↩2

  11. US National Library of Medicine, DailyMed. Epidiolex (cannabidiol) oral solution prescribing information, revised 2026. https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=8bf27097-4870-43fb-94f0-f3d0871d1eec ↩ ↩2 ↩3 ↩4

Common questions

Does CBD cure cancer?

No. There is no clinical trial evidence that CBD cures, shrinks or slows any cancer in people. The findings behind this claim come from cells in a dish and from animals. A 2021 review of clinical data and case reports found no strong trial evidence confirming an anticancer benefit.

Does CBD help with cancer symptoms?

A well-run Australian trial says no. Adults with advanced cancer in palliative care took CBD oil or placebo for 28 days, and CBD did not reduce overall symptom distress any more than palliative care alone. It also had no detectable effect on quality of life, depression or anxiety.

Can I take CBD during chemotherapy?

Talk to your oncologist or cancer pharmacist before taking it. CBD affects liver enzymes that process many medicines and can raise liver enzymes on its own, both of which matter during cancer treatment. Your team needs to know about everything you take.

Should I use CBD instead of cancer treatment?

No trial supports CBD as a replacement for cancer treatment. Delaying or refusing treatment that works can let a cancer progress. Tell your cancer team about anything you take or are thinking of taking, including CBD.

This page is general information, not medical or legal advice. Laws and evidence change; we show the date we last checked the facts at the top of every page. Talk to your doctor or pharmacist before starting, stopping or changing any medicine.

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