CBD LoveThe independent Australian guideSearch

CBD for dementia

No completed trial has tested CBD alone for dementia or agitation. Two trials of oils containing THC gave opposite results.

Facts checked 13 November 20264 min readHow we research
Not enough evidence

No completed trial of THC-free CBD in dementia was found, so no CBD-only dose has been tested. Two trials of CBD oils that also contained THC gave conflicting results for agitation.

How we grade evidence

There is not enough evidence to say whether CBD helps dementia. No completed trial has tested CBD on its own. The two trials we found used oils that also contained THC, and they reached opposite results on agitation. Nothing in human research shows CBD prevents or slows dementia.

What the research shows

Most carers who search for CBD are looking for help with agitation: the restlessness, distress and sometimes aggression that can come with dementia. That is also where the trials have focused.

  • An Israeli trial tested a CBD-rich cannabis oil that contained some THC. Agitation was reduced compared with placebo.1
  • A trial in Geneva tested a THC and CBD oil in people with severe dementia, using a crossover design (each person received both the oil and placebo at different times). The oil was no better than placebo for agitation.2

Both oils contained THC, the intoxicating compound in cannabis. That means neither trial can tell us what CBD alone does. And because the two results point in different directions, they do not settle the question even for combined products.

A Cochrane review, a type of rigorous independent evidence summary, has examined cannabinoids as a group for dementia.3 It does not provide evidence for CBD on its own.

Trials of THC-free CBD for agitation in Alzheimer’s disease have been registered. No results were found as of November 2026.4

What about protecting the brain?

Claims that CBD protects brain cells come from laboratory and animal studies. Reviews describe this activity “in preclinical models”, meaning before human testing.5 No human trial has shown that CBD prevents or slows any dementia. See CBD and brain health.

What doses were tested

No CBD-only dose has been tested in a completed dementia trial. The two agitation trials used oils combining CBD with THC, so their doses cannot be read as CBD doses.

In other conditions, effects of oral CBD in trials have mostly appeared at 300 mg a day or more.6 Whether any dose has an effect in dementia is unknown.

What Australian medical bodies say

No Australian medical body recommends CBD for dementia.

  • The TGA says medicinal cannabis should only be considered when registered medicines have been tried and failed.7
  • RACGP (the GPs’ college) says the evidence base is “limited and inconclusive” and does not recommend or encourage medicinal cannabis.8
  • RANZCP (the psychiatrists’ college) says there is insufficient evidence to support medicinal cannabis for mental disorders and is concerned about overprescribing.9

No cannabis medicine is registered in Australia for dementia.10

Risks to know about

  • Drowsiness. Sleepiness is one of the most common side effects of CBD, and it adds to the effect of other sedating medicines such as benzodiazepines, opioids and sedating antihistamines.11
  • Interactions. CBD blocks several liver enzymes that break down other medicines. Medicines flagged in the prescribing information include warfarin (a blood thinner), digoxin (a heart medicine) and clopidogrel (an anti-clotting medicine).11 A pharmacist should review the whole list. See CBD drug interactions.
  • THC. Many medicinal cannabis oils contain THC, which is intoxicating. Ask exactly what is in any product that is suggested.
  • Appetite and bowels. Reduced appetite and diarrhoea were more common with CBD than placebo in trials.11

See CBD for older adults and CBD side effects.

If you are considering it

  • Talk to the person’s GP or geriatrician, and ask them to assess the agitation itself before any new treatment is added.
  • Ask whether the product contains THC.
  • Ask for a pharmacist review of all medicines before any new medicine is started.
  • If any new treatment is prescribed, agree on what will be measured (for example, how often distress occurs) and a date to review it. TGA guidance says treatment should stop if benefit has not been shown.7

See talking to your GP about CBD.

Footnotes

  1. Randomised controlled trial of CBD-rich cannabis oil (containing THC) for agitation in dementia. https://pmc.ncbi.nlm.nih.gov/articles/PMC9486160/ ↩

  2. Randomised crossover trial of THC/CBD oil in severe dementia (Geneva). https://pubmed.ncbi.nlm.nih.gov/42613673/ ↩

  3. Cochrane review. Cannabinoids for the treatment of dementia. https://pmc.ncbi.nlm.nih.gov/articles/PMC8446835/ ↩

  4. ClinicalTrials.gov. Registered trial of cannabidiol for agitation in Alzheimer’s disease, NCT04436081. https://clinicaltrials.gov/study/NCT04436081 ↩

  5. Review of minor cannabinoids and preclinical neuroprotection. https://pmc.ncbi.nlm.nih.gov/articles/PMC13516590/ ↩

  6. Arnold JC, McCartney D, Suraev A, McGregor IS. The safety and efficacy of low oral doses of cannabidiol. Clinical and Translational Science, 2023. https://pubmed.ncbi.nlm.nih.gov/36259271/ ↩

  7. 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

  8. Royal Australian College of General Practitioners. Medical cannabis position statement (2019 update). https://www.racgp.org.au/advocacy/position-statements/view-all-position-statements/clinical-and-practice-management/medical-cannabis ↩

  9. Royal Australian and New Zealand College of Psychiatrists. Updated clinical memorandum: therapeutic use of medicinal cannabis, 2024. https://ranzcp.org/news-analysis/updated-clinical-memorandum-therapeutic-use-of-medicinal-cannabis ↩

  10. NPS MedicineWise. Medicinal cannabis: what you need to know. https://www.nps.org.au/professionals/medicinal-cannabis-what-you-need-to-know ↩

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

Common questions

Does CBD help dementia or Alzheimer's disease?

There is not enough evidence to say. No completed trial has tested CBD alone in people with dementia. Nothing in human research shows that CBD improves memory or slows the disease.

Does CBD calm agitation in dementia?

It is not known. Two trials have tested cannabis oils for agitation, but both oils contained THC as well as CBD, and their results conflicted. A trial of THC-free CBD for agitation in Alzheimer's disease is registered, but no results were found as of November 2026.

Can a carer give CBD oil to someone with dementia?

CBD is a prescription medicine in Australia, so it can only be supplied on a prescription for that person. Whether to prescribe is a decision for the doctor, who would weigh the person's other medicines, their risk of drowsiness, and who can consent to treatment.

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.

Didn't find what you needed? Ask us a question.

Keep reading