Conditions and evidence

What the research shows, condition by condition, with an evidence grade.

37 guides

Start here

How we grade evidence
The five evidence grades used on every condition page, what each one means, and why a study in mice or a glowing testimonial does not count for much.
What Australian doctors say
The positions of the TGA, RACGP, RANZCP, the Faculty of Pain Medicine and NPS MedicineWise on CBD and medicinal cannabis, in plain language.
Research to watch
Clinical trials of CBD that are under way or finished but not yet published, with a focus on Australia, and what each could tell us.

Strong evidence

Large, well-run trials agree, and a CBD medicine is approved for this use.

Strong evidence
Epilepsy
Large trials found high-dose prescription CBD, added to other medicines, reduced seizures in three rare, severe epilepsies. It is not proven for common adult epilepsy.

Limited evidence

A few small or early trials. Promising at best; not proven.

Limited evidence
Anxiety
A few small studies at 300 to 800 mg reported lower anxiety scores, but pooled trial results are not significant and no good trial has tested low doses.
Limited evidence
Psychosis and schizophrenia
A few small trials of high-dose CBD (600 to 1,000 mg a day) in schizophrenia gave mixed results. THC, unlike CBD, can trigger or worsen psychosis.
Limited evidence
Autism
Small trials of CBD-rich cannabis extracts, most containing some THC, reported changes in some behaviour measures. Purified CBD trials are reported as negative.
Limited evidence
Addiction
Early trials of high-dose CBD show some effect on cannabis use and heroin craving, no benefit for cocaine, and too little data for alcohol or smoking.

Not enough evidence

Mostly lab, animal or anecdotal reports. No good human trials yet.

Not enough evidence
Sleep and insomnia
The one published placebo-controlled trial of CBD alone for insomnia, an Australian study of 150 mg a night, found it similar to placebo on most sleep measures.
Not enough evidence
Chemotherapy nausea
No trial has tested CBD alone for chemotherapy nausea. Australian trials found benefit from capsules containing both THC and CBD, with more side effects.
Not enough evidence
Multiple sclerosis
No trial has tested CBD alone for MS spasticity. The evidence is for nabiximols (Sativex), a registered mouth spray that contains THC as well as CBD.
Not enough evidence
PTSD
There is not enough evidence that CBD helps PTSD. One small single-dose trial found no difference in anxiety, and pooled cannabinoid trials show no effect.
Not enough evidence
Depression
No completed placebo-controlled trial has tested CBD for major depression. A small trial in bipolar depression found no difference from placebo.
Not enough evidence
ADHD
No controlled trial has tested CBD on its own for ADHD. The one small trial of a cannabis medicine used a THC product and did not meet its main goal.
Not enough evidence
Parkinson's disease
Small trials have not found that CBD improves the movement symptoms of Parkinson's disease, and trials of CBD with THC have also been negative.
Not enough evidence
Dementia
No completed trial has tested CBD alone for dementia or agitation. Two trials of oils containing THC gave opposite results.
Not enough evidence
Endometriosis and period pain
No completed trial has tested whether CBD affects endometriosis or period pain. One small Australian trial was inconclusive and a UK trial is still running.
Not enough evidence
Acne, eczema and psoriasis
There is not enough evidence that CBD creams help acne, eczema or psoriasis. The largest acne trial has no peer-reviewed results and other studies are small.
Not enough evidence
Blood pressure
A single 600 mg dose of CBD lowered blood pressure in healthy men, but the effect faded within a week. It is untested as a treatment for hypertension.
Not enough evidence
Brain health
Claims that CBD protects the brain come from laboratory and animal studies. No human trial shows CBD prevents or slows any brain disease.
Not enough evidence
Tourette syndrome
No trial has tested CBD on its own for tics. The promising Australian trial used an oil containing THC as well as CBD, and pure high-CBD cannabis did not help.
Not enough evidence
Tinnitus
No human trial has tested CBD for tinnitus. A rat study found a THC and CBD mix made tinnitus more likely, and cannabis users report tinnitus more often.
Not enough evidence
Menopause
No published trial has tested CBD for hot flushes or other menopause symptoms. Menopause experts list cannabinoids among treatments they do not recommend.
Not enough evidence
Nerve pain
The largest trial of oral CBD for nerve pain found no benefit, and a CBD cream failed for chemotherapy neuropathy. A few small studies were positive.
Not enough evidence
Restless legs
No trial has tested CBD on its own for restless legs syndrome. A small analysis in Parkinson's patients found 75 to 300 mg a day no better than placebo.
Not enough evidence
OCD
CBD has not been shown to help OCD. High-CBD cannabis did no better than placebo in a lab study, and the only CBD trial was tiny and poorly balanced.
Not enough evidence
Inflammation
CBD reduces inflammation in lab and animal studies. In people, trials in inflammatory conditions and after exercise have mostly found no benefit.
Not enough evidence
Stress
Stress is one of the top reasons people use CBD, but trials in healthy adults and stressed groups have mostly found no effect beyond placebo.

Trials show no benefit

Controlled trials have tested CBD for this and found it no better than placebo.

Trials show no benefit
Chronic pain
Placebo-controlled trials of CBD alone for pain, at doses from 20 mg to 600 mg, have almost all found it no better than placebo.
Trials show no benefit
Arthritis
Two placebo-controlled trials of CBD for arthritis pain, one at 20 to 30 mg a day and one at 600 mg a day, both found no benefit.
Trials show no benefit
Cancer
CBD is not a cancer treatment. An Australian trial in advanced cancer found CBD oil did not improve symptoms beyond palliative care alone.
Trials show no benefit
Migraine
The one controlled trial found CBD alone was no better than placebo for a migraine attack. No trial has tested CBD for preventing migraine.
Trials show no benefit
IBS, Crohn's and colitis
Small controlled trials found CBD no better than placebo for Crohn's disease and IBS pain. For ulcerative colitis there is not enough evidence.
Trials show no benefit
Diabetes
The one controlled trial, in 62 people with type 2 diabetes, found CBD alone did not improve blood sugar control over 13 weeks.
Trials show no benefit
COVID-19
A randomised trial of 300 mg of CBD a day for 14 days found it made no difference to the course of mild to moderate COVID-19.
Trials show no benefit
Fibromyalgia
The largest trial of CBD for fibromyalgia gave 200 people 50 mg a day for 24 weeks. Pain fell slightly more with placebo than with CBD.
Trials show no benefit
Glaucoma
CBD does not lower eye pressure in the one human trial, and a 40 mg dose briefly raised it. Animal work suggests CBD may block THC's pressure-lowering effect.