Cannabidiol shows no significant benefit for treating psychotic disorders, new study finds

Recent research published in the Journal of Psychopharmacology suggests that cannabidiol, a non-intoxicating compound found in cannabis, might not be an effective treatment for psychotic disorders. By analyzing data from multiple clinical trials, the scientists found no significant evidence that the substance improves symptoms of psychosis compared to a placebo or standard medications. The findings indicate that while the compound is generally safe to use, patients and healthcare providers should view it as an experimental rather than a proven therapy for these mental health conditions.

Cannabis is a complex plant containing dozens of active chemical compounds. The most well-known is delta-9-tetrahydrocannabinol, or THC, which is responsible for the psychological high associated with marijuana use. High levels of THC exposure have been linked to an increased risk of developing psychotic disorders.

Psychotic disorders, such as schizophrenia, are mental health conditions that alter a person’s sense of reality. Symptoms often include hallucinations, delusions, and severe cognitive issues. Current antipsychotic medications can help manage these symptoms, but they often come with heavy side effects, leading the medical community to search for gentler alternatives.

Cannabidiol, commonly known as CBD, is another major compound in cannabis that does not produce intoxicating effects. Laboratory and animal studies have hinted that CBD might actually reduce psychotic symptoms. Early laboratory work provides evidence that it interacts with the body’s endocannabinoid system, a complex cell-signaling network that helps regulate functions like mood, sleep, and memory.

Specifically, CBD is thought to boost levels of anandamide, a brain chemical associated with well-being. It also interacts with serotonin receptors to calm nervous system activity. Because of these promising signs in laboratory settings, clinical trials testing CBD on human patients with psychosis have gained massive attention.

Free daily newsletter

Some medical experts have highlighted these trials as some of the most impactful psychiatric research of recent years. Yet, individual studies have often been too small to provide definitive answers about whether the chemical actually helps patients in the real world. A team of researchers sought to combine and evaluate all the available evidence from previous human studies.

The research team was led by Mattia Marchi from the University of Modena and Reggio Emilia in Italy, alongside a group of medical scientists specializing in mental health. They aimed to determine if CBD is truly effective and tolerable for people diagnosed with schizophrenia spectrum disorders.

To achieve this goal, the scientists performed a systematic review and meta-analysis. A meta-analysis is a statistical technique that combines the results of multiple independent studies to find common trends and provide a more reliable estimate of a treatment’s effect. The team searched major scientific and medical databases for randomized controlled trials published up until July 2025.

Randomized controlled trials are considered the gold standard in medical research. They randomly assign participants to receive either the treatment being tested or a comparison substance, like a fake pill known as a placebo. The authors narrowed their focus to eight specific trials.

Six of these studies had been published in peer-reviewed scientific journals, while two were unpublished trials sourced from a public registry. In total, the analysis included 288 adult participants who had been diagnosed with psychotic disorders. Within this group, 116 participants received CBD treatments, and 117 were placed in control groups receiving either a placebo or an existing antipsychotic medication.

Another 55 participants took part in a crossover study where they received both treatments at different times. In a crossover design, a patient might take CBD for a set period, take a break, and then take a placebo. This structure allows researchers to compare how the same individual responds to both options.

The CBD was administered orally. The median daily dose was 800 milligrams, though exact amounts varied between studies. The duration of the trials ranged drastically, with researchers following up with patients anywhere from 20 minutes to 12 weeks after treatment.

When looking at the combined data, the researchers found that CBD did not produce a statistically meaningful improvement in psychosis severity. They evaluated multiple categories of symptoms, including positive symptoms like hallucinations and delusions. They also examined negative symptoms, which involve a loss of normal functioning, such as emotional flatness or social withdrawal.

In all these areas, as well as in tests of cognitive impairment, the substance failed to perform significantly better than the control treatments. In one study, CBD was compared directly to an active antipsychotic medication named amisulpride. While this specific trial showed no difference in effectiveness between the two, it was not designed to prove that they are perfectly equivalent.

Safety and tolerability were also primary focuses of the review. The authors noted that CBD tends to be well tolerated by the participants. The rates of side effects and trial dropouts were very similar between the groups taking CBD and those taking a placebo or standard medication.

One trial did report a participant death in the CBD group. However, medical examiners ruled out CBD intoxication as the cause of death. The team also broke down the data into smaller subgroups to see if specific factors influenced the outcomes.

They looked at the length of the trials, comparing acute, short-term, and long-term effects. None of these timeframes showed a significant benefit from taking CBD. Interestingly, the data hinted at a potential exception regarding patients who were active cannabis users.

Trials that included participants who regularly used recreational cannabis showed slightly larger improvements when treated with CBD. The researchers suggest that this might reflect CBD helping to reduce the negative effects of recreational cannabis use, rather than directly treating the underlying psychotic disorder itself. This specific finding was based on a very small amount of data, making it a preliminary observation rather than a proven fact.

The authors also discussed the financial realities of CBD treatment. They noted that the pharmaceutical-grade CBD formulations tested in these trials are substantially more expensive than commonly used antipsychotic medications. While cheaper CBD preparations are widely available in retail outlets, these over-the-counter products usually differ wildly in dose, purity, and regulation, meaning they cannot be assumed to provide the same effects as medical-grade formulations.

Readers should be aware of some limitations in the current body of research. The most significant issue is the small number of available trials and the low number of total participants. This small sample size reduces the statistical power of the analysis, meaning that subtle but potentially real benefits of CBD might have been missed.

The included studies also suffered from significant differences in design. Some trials only tracked patients for a few minutes after a single dose, which does not reflect how medications are typically used to treat chronic mental health conditions over time. Additionally, the quality of evidence across the studies was rated as low to very low, largely due to issues like incomplete reporting or potential biases in how the original experiments were run.

The researchers emphasize that larger clinical trials are needed to reach more definitive conclusions. They specifically suggest that future research should focus on patients whose psychosis is directly related to cannabis use. By targeting this specific group, scientists might clarify whether CBD serves as a specific antidote to marijuana-induced psychosis.

Until such data emerges, the authors advise that CBD remains an experimental approach. Current evidence simply does not support its clinical use as a standard medical treatment for schizophrenia or related conditions. Larger clinical trials are currently underway across multiple research centers, which will hopefully provide higher-quality data to establish exactly what role CBD might play in future psychiatric care.

The study, “Cannabidiol for psychotic disorders: A meta-analysis of randomized controlled trials,” was authored by Mattia Marchi, Karim Rachedi, Alessia Bof, Giulio Mele, Luca Pingani, Silvia Ferrari, and Gian Maria Galeazzi.