A landmark\u00a0Lancet\u00a0Psychiatry\u00a0paper published today \u2013 the largest-ever review of the safety and efficacy of cannabinoids across a range of\u00a0mental\u00a0health conditions \u2013 found no evidence that medicinal cannabis is effective in treating anxiety,\u00a0depression\u00a0or post-traumatic stress disorder (PTSD).\u00a0<\/p>\n
The study comes amid more than\u00a0one million prescription approvals\u00a0and a\u00a0tripling of sales\u00a0of cannabinoid medications\u00a0(including both cannabidiol (CBD) and tetrahydrocannabinol (THC) products)\u00a0in Australia over the past four years, often for the treatment of mental health and substance-use disorders.\u00a0<\/p>\n
The study’s lead author,\u00a0Dr Jack Wilson\u00a0at\u00a0the\u00a0University of Sydney’s\u00a0The Matilda Centre,\u00a0said the results call into question the approval of medicinal cannabis for the treatment of\u00a0depression,\u00a0anxiety\u00a0and PTSD.\u00a0<\/p>\n
“Though our paper didn’t specifically look at this, the\u00a0routine use of medicinal cannabis\u00a0could be doing more harm than good by worsening mental health outcomes, for example\u00a0a greater risk of psychotic symptoms and developing cannabis use disorder,\u00a0and delaying the use of more effective treatments,” he said.\u00a0<\/p>\n
More than 700,000 Australians have reported using medicinal cannabis to treat over 250 different health conditions.\u00a0The research\u00a0found\u00a0evidence\u00a0to suggest\u00a0that\u00a0medicinal cannabis\u00a0could\u00a0potentially\u00a0be\u00a0beneficial\u00a0for\u00a0some conditions \u2013 such as the\u00a0treatment of\u00a0cannabis\u00a0use disorder\u00a0(otherwise known as cannabis dependency), autism, insomnia, and\u00a0tics\u00a0or Tourette’s syndrome.\u00a0<\/p>\n
Dr Wilson said:\u00a0“But\u00a0the\u00a0overall quality of\u00a0evidence\u00a0for these other conditions, such as autism and insomnia,\u00a0was low. In the absence of robust\u00a0medical or counselling\u00a0support, the use of medicinal cannabis\u00a0in these cases\u00a0are\u00a0rarely\u00a0justified.\u00a0<\/p>\n
“There is, however,\u00a0evidence that medicinal cannabis may be beneficial in\u00a0certain health conditions, such as\u00a0reducing\u00a0seizures associated with some forms of epilepsy,\u00a0spasticity among those with\u00a0multiple sclerosis, and\u00a0managing certain types of pain,\u00a0but\u00a0our study shows the\u00a0evidence for mental health disorders falls short.\u00a0<\/p>\n
“In the case of\u00a0autism\u00a0specifically, while the study showed some evidence medicinal cannabis could assist with a reduction in symptoms, it is worth noting that there is no one \u2013 or universal \u2013 experience of autism, so this\u00a0finding\u00a0should be treated with caution.”\u00a0<\/p>\n
The study found that medicinal cannabis was not effective for every type of substance-abuse\u00a0disorder. While medicinal cannabis may\u00a0help\u00a0with cannabis dependence,\u00a0it was found to\u00a0increase cocaine cravings among people with cocaine-use disorder\u00a0<\/p>\n
“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. When administered alongside psychological therapy, an oral formulation of cannabis was shown to reduce cannabis smoking,”\u00a0Dr Wilson\u00a0said.\u00a0<\/p>\n
“However, when medicinal cannabis was used to treat people with cocaine-use disorder, it increased their cravings. This means it should not be considered for this purpose and may, in fact, worsen cocaine dependence,” he said.\u00a0<\/p>\n
Researchers urge greater regulation\u00a0for prescribing of medicinal cannabis\u00a0<\/p>\n
The rapid expansion in medicinal cannabis\u00a0use\u00a0and prescribing rates has raised concerns among major medical bodies, including the Australian Medical Association (AMA) and the Pharmacy Guild of Australia, about the\u00a0largely unregulated\u00a0growth in prescribing and the uncertainty surrounding the efficacy<\/a> and safety of these products.\u00a0<\/p>\n In response, the Therapeutic Goods Administration (TGA)\u00a0initiated\u00a0a review of the regulatory oversight of medicinal cannabis, with\u00a0more than\u00a0500\u00a0responses published in February.\u00a0<\/p>\n “Our study\u00a0provides\u00a0a comprehensive and independent assessment of the benefits and risks of cannabis medicines, which may\u00a0support the TGA and clinicians to make evidence-based decisions, helping to ensure patients receive effective treatments while minimising harm from ineffective or unsafe cannabis products,”\u00a0Dr Wilson\u00a0said.\u00a0<\/p>\n The systematic review and meta-analysis included results from 54 randomised controlled trials (RCTs) published over a\u00a045-year\u00a0period (1980-2025) worldwide.\u00a0<\/p>\n Source:<\/p>\n Journal reference:<\/p>\n