Will medicinal cannabis help my mental health? Here are the evidence and the risks

Anxiety, depression and post-traumatic stress disorder (PTSD) are among the most common mental health conditions for which Australians are prescribed medicinal cannabis.

Most prescriptions for mental health conditions, and for other conditions more broadly, are for products containing higher levels of THC (tetrahydrocannabinol). This is the part of cannabis that causes a “high” and can affect thinking and mood.

Many of these prescriptions are for inhaled products, such as dried leaf or flower that people smoke or inhale.

This pattern of use – of inhaled, higher-THC content for mental health conditions – appears to be partly driven by prescribing trends among 18 to 44-year-old men.

For anxiety alone, there are almost three times more approvals for the products containing the highest levels of THC than for products containing only CBD (cannabidiol).

But this prescribing pattern doesn’t line up with the best available research. Most higher-quality clinical trials for anxiety have tested CBD-based products, not THC.

This is just one example of how Australians are using medicinal cannabis to treat mental health conditions without the best available evidence to back it.

Let’s start with anxiety

Anxiety is the most common mental health reason people seek medicinal cannabis in Australia.

There is emerging evidence CBD may help some people with anxiety, but the findings are inconsistent.

The largest and most comprehensive systematic review on medicinal cannabis and mental health found it did not meaningfully improve anxiety symptoms. The authors said we still need larger, high-quality trials, and studies that reflect how people use medicinal cannabis in the real world.

Evidence for THC is even more mixed. In our previous article we described how some people find THC makes them feel calmer, but others say it worsens their anxiety. As few trials have investigated THC for anxiety, it is hard to draw firm conclusions.