Medicinal cannabis has become increasingly popular in recent years.
Many people believe it can help with a wide range of health problems, including mental health conditions such as anxiety, depression, and post-traumatic stress disorder (PTSD).
In several countries, doctors can prescribe cannabis-based medicines, and many patients turn to these treatments hoping they will improve their emotional well-being.
However, a major new scientific review suggests that the benefits for mental health may be far smaller than many people expect.
The research was published in the journal Lancet Psychiatry and represents the largest review so far examining the safety and effectiveness of cannabinoids for mental health conditions.
Cannabinoids are chemical compounds found in the cannabis plant. The most well-known are THC, which produces the “high” feeling associated with marijuana, and CBD, which does not cause intoxication but is often marketed as having calming or therapeutic effects.
Over the past decade, the use of medicinal cannabis has expanded rapidly. Surveys suggest that about 27 percent of adults aged 16 to 65 in the United States and Canada have used cannabis for medical reasons at some point.
Among these users, around half report using it to try to manage mental health problems such as anxiety, depression, or trauma-related stress. This growing popularity has raised important questions about whether cannabis treatments truly work for these conditions.
To answer this question, researchers led by Dr. Jack Wilson from the University of Sydney’s Matilda Centre conducted a large systematic review and meta-analysis. This type of study combines data from many different clinical trials in order to produce a clearer overall picture of the evidence.
By analyzing multiple studies together, scientists can better understand whether a treatment consistently works across different groups of patients and research settings.
The team examined 54 randomized controlled trials conducted between 1980 and 2025 around the world. Randomized controlled trials are considered one of the most reliable ways to test medical treatments because participants are randomly assigned to receive either the treatment being studied or a comparison treatment such as a placebo. This helps reduce bias and improves the reliability of the findings.
After reviewing all of these trials, the researchers found no convincing evidence that medicinal cannabis is effective for treating anxiety disorders, depression, or PTSD. According to Dr. Wilson, these results challenge the growing belief that cannabis-based medicines are useful treatments for these common mental health conditions.
The researchers also warned that regular use of medicinal cannabis could potentially create additional problems. Although this specific review did not focus on long-term harms in detail, other research suggests that cannabis use may increase the risk of certain negative outcomes.
These include the development of cannabis use disorder, which means becoming dependent on cannabis, as well as an increased risk of psychotic symptoms in vulnerable individuals. Another concern is that patients might delay seeking treatments that are already known to work well, such as psychological therapies or established medications.
Despite the lack of evidence for many mental health conditions, the study did identify a few areas where cannabis-based treatments might offer some benefit.
For example, there was limited evidence suggesting that medicinal cannabis could help people with cannabis use disorder reduce their own cannabis smoking when used in controlled oral forms alongside psychological therapy. This approach is somewhat similar to how methadone is used to help people with opioid addiction.
The researchers also found some early evidence that cannabinoids might help certain symptoms related to autism, insomnia, and tic disorders such as Tourette’s syndrome. However, the quality of the evidence in these areas was generally low.
This means the existing studies were small or had limitations that make the results uncertain. As a result, scientists say these findings should be treated with caution until stronger research becomes available.
In addition, the researchers noted that medicinal cannabis has already shown clearer benefits for some physical health conditions.
For example, certain cannabis-based medications can reduce seizures in rare forms of epilepsy, relieve muscle stiffness in people with multiple sclerosis, and help manage specific types of chronic pain. These uses have been studied more extensively and have stronger scientific support than mental health applications.
One particularly important finding from the review involved people with substance use disorders. While medicinal cannabis might help reduce cannabis dependence in some cases, the researchers found the opposite effect for cocaine addiction.
In studies involving people with cocaine use disorder, cannabis-based treatments actually increased cravings for cocaine. This suggests that cannabis medicines should not be used as a treatment for this condition and may even make it worse.
The rapid growth of medicinal cannabis prescribing has raised concerns among several major medical organizations.
Groups such as the American Medical Association have warned that regulations in some places have not kept pace with the expanding market. This means cannabis-based products are sometimes prescribed even when there is limited evidence that they are safe or effective.
Dr. Wilson said the goal of the research was to provide a clear and independent summary of the available evidence so doctors and policymakers can make better decisions.
By understanding both the potential benefits and the risks of cannabis-based medicines, clinicians can guide patients toward treatments that are more likely to help while avoiding those that may be ineffective or harmful.
Overall, the study suggests that the enthusiasm surrounding medicinal cannabis for mental health may currently be ahead of the scientific evidence. While cannabis-based medicines may have important roles in certain medical conditions, the evidence for treating anxiety, depression, and PTSD remains weak.
In reviewing the findings, the research highlights several key lessons. First, popularity and widespread use do not necessarily mean a treatment is effective. Many people may turn to cannabis because it is easily available or widely discussed in the media, but this does not guarantee real clinical benefits.
Second, high-quality research is essential before new treatments become widely accepted. Randomized controlled trials provide the strongest evidence, and more studies are still needed to fully understand when cannabinoids might be helpful and when they are not.
Finally, the results emphasize the importance of evidence-based medicine. Patients struggling with mental health problems should have access to treatments that are proven to work, including psychological therapies, medications, and professional support.
While cannabis-based treatments may continue to be studied, the current evidence suggests they should not replace established mental health care.
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