Canabidiol in the treatment of bipolar disorder: what do studies say?

Research indicates promising effects of CBD, but experts urge caution and more scientific evidence

Published on 07/28/2025

Canabidiol in the treatment of bipolar disorder: what do studies say?

Research points to new paths for the treatment of bipolar affective disorder, including the use of cannabidiol (CBD) as a complementary therapy. | Illustrative image: Canva Pro

Bipolar affective disorder is a chronic psychiatric condition marked by alternating episodes of depression and mania or hypomania. It affects about 6 million Brazilians, according to the Brazilian Association of Psychiatry (ABP). Given the limitations of conventional treatments, interest is growing in the use of cannabidiol (CBD) as a therapeutic alternative, especially in the context of medicinal cannabis.

What is cannabidiol and how does it act in the brain?

Cannabidiol (CBD) is one of the main non-psychoactive compounds of the plant Cannabis sativa. Studies indicate that it may act in the regulation of the endocannabinoid system, which is involved in functions such as mood, sleep, appetite, and memory — areas often affected in people with bipolar disorder.

Fiocruz study points to initial improvement with high doses of CBD

One of the most relevant studies was conducted by the Oswaldo Cruz Foundation (Fiocruz), with support from Anvisa, published in the Cannabis and Mental Disorders Report (2020). In the research, bipolar patients received high doses of CBD (600 mg to 1200 mg per day), in combination with olanzapine, for 20 days. On the 21st day, the CBD was replaced with a placebo.

The results showed a 37% reduction in manic symptoms (measured by the Young Mania Rating Scale) and 33% overall improvement (by the Brief Psychiatric Rating Scale) — however, the positive effects were limited to the initial phase of treatment.

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Patient reports and observational studies suggest mood-stabilizing effects

A study published in the Journal of Cannabis Research (2019) gathered patient reports of using cannabidiol on their own to alleviate bipolar symptoms. The data, although preliminary, indicate that CBD may have mood-stabilizing effects, acting on emotional modulation via the endocannabinoid system.

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Systematic review reinforces the need for more studies

A systematic review published in 2023 in Frontiers in Psychiatry evaluated the use of medicinal cannabis in various psychiatric disorders, including bipolar disorder. The conclusion is clear: there is still no robust scientific evidence to justify the use of CBD as a primary or adjunct treatment. Researchers recommend more randomized and controlled studies to prove efficacy and safety.

Check out the full review

Risks associated with the use of THC-rich cannabis

Another study, published in the BMC Psychiatry (2019), analyzed the impact of using cannabis with high THC content in bipolar patients and concluded that the compound can exacerbate manic episodes. This raises an alert: while pure CBD may have beneficial properties, THC products should be avoided by people with bipolar disorder.

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Use of CBD in bipolar disorder requires medical guidance

The Brazilian Association of Psychiatry (ABP) classifies the use of cannabidiol in the treatment of bipolar disorder as category F of scientific evidence, meaning that studies are still insufficient to validate safe and effective clinical use.

Experts emphasize that patients interested in therapies with medicinal cannabis should seek specialized medical guidance and opt for products regulated by Anvisa.

Masterclass led by Pierro explores the role of the endocannabinoid system in mood regulation and relief of symptoms of bipolar disorder, depression, and chronic pain

Understanding how the endocannabinoid system acts in mood regulation, sleep, and pain perception has become one of the focuses of contemporary medicine. This is the proposal of the new episode of the podcast Deusa Cast, which presents an exclusive masterclass on endocannabinoid medicine, led by the specialist Pierro.

During the episode, Pierro explains how advances in understanding this system have allowed the development of more effective and personalized therapeutic approaches to treat conditions such as bipolar affective disorder, depression, anxiety, sleep disorders, and chronic pain.

“Endocannabinoid medicine represents a new frontier in mental and emotional healthcare. Understanding how this system works is essential to open up new therapeutic possibilities,” says the specialist.

The content is aimed at both healthcare professionals and the general public interested in new evidence-based treatment approaches.