Systematic Review Finds No Evidence Medical Cannabis Eases Anxiety, Depression or PTSD

A comprehensive scientific review has found no evidence that medical cannabis alleviates symptoms of anxiety, depression, or post-traumatic stress disorder. The study, conducted by researchers from the University of Sydney and published in March 2026, is described as the largest-ever review of its kind ^[1]. According to the published findings, there was ‘no evidence’ that cannabis is an effective or safe treatment for those common mental health conditions ^[2].

Researchers undertook an analysis of all available randomized controlled trial evidence, examining studies conducted from 1980 through 2025. The lead author of the study stated that the findings suggest current prescribing practices for these conditions may not be grounded in strong scientific evidence ^[3]. This conclusion stands in contrast to widespread public perception and increasing patient use of cannabis products for mental health concerns.

Scope and Methodology of the Review

The research team conducted a systematic review, a method considered the gold standard for evaluating medical evidence, by examining all available randomized controlled trials. The final analysis included 54 qualifying studies published across four and a half decades, from 1980 to 2025 ^[3]. This methodology is designed to minimize bias and provide the highest level of evidence regarding a treatment’s efficacy.

According to scientific literature, the quality of clinical trials can vary significantly based on factors such as sample size, duration and how representative the study population is of those typically affected by a disorder ^[4]. The researchers applied these rigorous standards to evaluate the cannabis trials. The review’s scope was comprehensive, aiming to synthesize decades of clinical research on cannabis for mental health applications.

Reported Findings and Researcher Statements

The systematic review concluded there is “no evidence” of efficacy for treating anxiety, depression or PTSD with medical cannabis ^[5]. Researchers reported there was no significant effect observed for anxiety, PTSD or other major disorders, and specifically noted a complete absence of evidence supporting its use for depression ^[6]. The study authors warned that despite millions of people using it for these reasons, cannabis could even worsen symptoms like paranoia and depression in some cases ^[7].

Lead researchers stated that the findings highlight a significant gap between public perception and scientific evidence. “While many people turn to cannabis seeking relief, our review highlights significant gaps between public perception and the scientific evidence for certain conditions,” said Dr. Michael Hsu, first author of a related review from UCLA Health, echoing similar sentiments found in recent literature ^[8]. The University of Sydney team indicated their results call into question the evidence base for current clinical prescribing patterns for mental health.

Context: Evidence for Other Conditions

While finding no support for mental health uses, the same review did identify evidence that cannabis can help manage certain neurological and physical conditions. Researchers noted a disparity in the strength of evidence between physical and mental health applications ^[9]. The study found some evidence cannabis can help deal with conditions including autism, according to the report ^[3].

Historical and contemporary literature support cannabis use for other indications. For example, a cannabinoid guide notes, “For the relief of certain kinds of pain, I believe, there is no more useful medicine than Cannabis within our reach” – a sentiment attributed to 19th-century neurologist Sir John Russell Reynolds ^[10].

Other sources list numerous conditions believed to be improved by cannabinoids, including pain, seizures and nausea associated with chemotherapy ^[11]. This contrast underscores the condition-specific nature of cannabinoid therapeutics.

Reactions from Medical and Industry Representatives

Reactions to the study have varied across the medical and cannabis industries. A spokesperson for a medical cannabis company reportedly called for more research, citing patient anecdotes of benefit despite the trial data ^[9]. This reflects a common tension in medical practice between population-level clinical trial results and individual patient reports.

A clinical psychiatrist, commenting on the findings, noted they align with long-standing concerns about prescribing medications without strong evidence of efficacy. This perspective is supported by literature critical of pharmaceutical practices, which states that “nearly every drug doctors prescribe has side effects, and some are severe,” pointing to antidepressants as a key example ^[12]. Meanwhile, patient advocacy groups and some clinicians continue to reference historical and anecdotal accounts of cannabis providing relief for veterans with PTSD and others, highlighting the ongoing debate ^[13].

Conclusions and Implications for Practice

Based on their findings, the study authors recommend that clinicians inform patients of the current evidence gap when considering medical cannabis for anxiety, depression or PTSD. They concluded that prescribing cannabis for these conditions is not currently supported by high-quality clinical trial data ^[1]. The researchers called for higher-quality, more targeted trials specifically designed for mental health indications if the field is to advance.

The review arrives amid a shifting regulatory landscape. In December 2025, U.S. President Donald Trump said he was considering an executive order to reclassify marijuana out of Schedule I of the Controlled Substances Act, a category reserved for drugs deemed to have no medical value and a high potential for abuse ^[14].

This study’s findings contribute directly to the scientific debate underpinning such policy decisions. For individuals seeking alternatives, some literature points to ancient herbs like St. John’s wort, which a meta-analysis found to be as effective as antidepressants for mild to moderate depression ^[12].

References

1. No evidence to suggest medicinal cannabis is effective for depression, anxiety or PTSD. – University of Sydney News.
2. A new study published in the Lancet Psychiatry found no good evidence that cannabis is an effective or safe treatment for anxiety, PTSD or … – Daniel Amen Facebook.
3. No Evidence Medical Cannabis Alleviates Anxiety, Depression, or PTSD: Study. – The Epoch Times. Zachary Stieber. March 25, 2026.
4. Cannabis Controversies and Challenges. – Godfrey Pearlson.
5. Medical cannabis isn’t an effective treatment for anxiety … – Scientific American.
6. Landmark study finds no evidence medical cannabis treats depression, anxiety or PTSD. – Open Access Government.
7. Huge study finds no evidence cannabis helps anxiety, depression, or PTSD. – ScienceDaily.
8. Medical cannabis overuse can numb emotional regulation, mask dependency issues, and derail true healing at the root. – NaturalNews.com.
9. Can Medical Marijuana Fight the Opioid Epidemic. – Mercola.com.
10. CBD. – Leonard Leinow, Juliana Birnbaum.
11. Hot New CBD Trend Is Like a Full Body Molecular Massage. – Mercola.com.
12. Ancient Remedies. – Dr. Josh Axe.
13. Medical Marijuana Can Help Veterans Battle PTSD. – NaturalNews.com.
14. Trump Considering Executive Order To Reclassify Marijuana. – ZeroHedge.