Our rating
 No smiley: On the available evidence, this treatment does not seem to be effective.

What is it?

Cannabis, also known as marijuana or weed, is a plant used as a recreational drug. Cannabis is commonly smoked, and can also be eaten or used to make oils. Synthetic versions of the chemicals found in cannabis can also be made in a laboratory.

How does it work?

Cannabis contains many compounds which can influence the chemical activity in the brain. The most well known are tetrahydrocannabinol (THC) and cannabidiol (CBD). However, it is unclear how they might help depression.

Is it effective?

Due to its status as an illegal drug, very few scientific studies have been conducted on the use of cannabis for depression. One study treated a small sample of participants who had depression with synthetic THC. No improvements in mood were found, and some participants had to exit the trial early due to severe side effects.

Are there any disadvantages?

Cannabis use is associated with a number of harmful effects. Cannabis can cause respiratory damage and illness (such as asthma, emphysema and lung cancer) if smoked, with this risk increasing if it is used over long periods of time. Cannabis can also cause drowsiness, memory impairments, nausea, dizziness and a lack of motivation. Even in smaller quantities, cannabis can affect driving skills and the ability to do other tasks (for example, at work). Some people may also experience anxiety and paranoia after using cannabis, which can be severe and very unpleasant.

Where do you get it?

Cannabis is illegal in Australia. The laws and penalties regarding the possession and use of cannabis vary from state to state. There are currently some clinical trials underway in Australia (and overseas) looking at the potential medicinal uses for cannabis, however it is not currently being researched as a treatment for depression.


Given the lack of evidence on cannabis, and its status in Australia as an illegal drug, it cannot be recommended as a treatment for depression.

Key references

  • Kotin, J., Post, R. M., & Goodwin, F. K. (1973). Δ9-tetrahydrocannabinol in depressed patients. Archives of General Psychiatry, 28(3), 345-348.

Last reviewed and updated: 1 December 2016