Weed is actually ‘rarely justified’ to treat anxiety or depression, says major scientific review

A little green might not be a cure for the blues.

New research suggests medical marijuana isn’t the mental health miracle many hope for, finding little evidence that it can effectively treat conditions like anxiety, depression or PTSD.

“In the absence of robust medical or counselling support, the use of medicinal cannabis in these cases [is] rarely justified,” Dr. Jack Wilson, lead author of the study, said in a press release.

The study, billed as the “largest review of medical cannabis to date,” analyzed 54 randomized controlled trials published between 1980 and 2025.

Wilson and his colleagues looked at a wide range of conditions and different forms of marijuana — including cannabidiol (CBD) and tetrahydrocannabinol (THC) products.

But the results didn’t leave them with very high hopes.

The researchers found that cannabis had “no benefit” for treating bipolar disorder, anxiety, ADHD, OCD, anorexia nervosa or psychotic disorders.

For depression, a common reason people turn to medical cannabis, the team couldn’t find any trials testing it as a primary treatment.

“Some people may experience legitimate benefits, and that’s great,” Wilson, a postdoctoral researcher at the University of Sydney’s Matilda Centre for Research in Mental Health and Substance Use, told Reuters.

“But when we look at the evidence as a whole, we just don’t see that the evidence is quite there for the routine use of these medicines.”

Marijuana also fell short when it came to some substance-use disorders.

In fact, for people with cocaine-use disorder, medical cannabis actually increased cravings, which the researchers said could potentially make their dependency worse.

There was a silver lining, though: The team found some promise for treating cannabis-use disorder — a complex condition in which people can’t stop using marijuana even when it starts causing serious problems in their health or daily life.

“Similar to how methadone is used to treat opioid-use disorder, cannabis medicines may form part of an effective treatment for those with a cannabis-use disorder,” Wilson said.

“When administered alongside psychological therapy, an oral formulation of cannabis was shown to reduce cannabis smoking.”

The researchers also identified some “promising findings” for other conditions, including reducing symptoms of autism spectrum disorder, improving sleep in insomnia and cutting the severity of tics in Tourette’s syndrome.

Still, Wilson cautioned, “the overall quality of evidence for these other conditions, such as autism and insomnia, was low.”

Even so, with few safe, effective treatment options available, the team noted that the findings are “encouraging” and worth further investigation.

Medicinal cannabis has also shown benefits in more established areas, like reducing seizures in certain types of epilepsy, easing spasticity in multiple sclerosis and managing certain kinds of pain.

Overall, though, the study authors concluded that “the evidence for mental health disorders falls short.”

Across the country, 40 states — along with DC and four US territories — have legalized cannabis for medical purposes over the past three decades.

Clearly, it’s taken root. Studies show that 27% of people ages 16 to 65 across the US and Canada have tried medical cannabis, and about half of them use it to manage their mental health.

It’s easy to see why: In the US alone, more than 1 in 5 adults, or a staggering 59.3 million people in 2022, live with a mental illness.

But Wilson said the findings raise serious questions about whether medicinal cannabis should be approved for conditions like depression, anxiety and PTSD.

“Though our paper didn’t specifically look at this, the routine use of medicinal cannabis could be doing more harm than good by worsening mental health outcomes, for example a greater risk of psychotic symptoms and developing cannabis use disorder, and delaying the use of more effective treatments,” he said.