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Medical Marijuana for Schizophrenia: Weighing the Risks and Benefits

As clinicians wait for more evidence, here’s where cannabis data fits into schizophrenia treatment protocols.

With more states legalizing medical as well as recreational for marijuana, it’s only a matter of time before your patients or clients ask about CBD, cannabis, or marijuana. But for individuals diagnosed with schizophrenia, marijuana – in any form – can actually worsen the symptoms, according to Julie Foster, FNP, MSN, medical director of Pohala Clinic, a center for integrative care and alternative medicine approaches located in Portland, Oregon.

That’s why she and many other experts recommend that people with schizophrenia or a tendency toward psychosis steer clear of all forms of the substance.

The Chemistry of Marijuana

Marijuana is a mixture of the dried flowers of Cannabis sativa plant that consists of more than 500 chemicals. This includes delta-9-tetrahydrocannabinol (THC), which has hallucinogenic properties and is responsible for the “high” and cannabidiol (CBD), touted to provide health benefits such as antioxidative, anti-inflammatory, and neuroprotection effects, according to NIH’s National Institute on Drug Abuse (NIDA). Both “medical” and “recreational” marijuana can contain a mixture of THC and CBD.

Additionally, there are a plethora of products marketed as CBD or hemp-infused including drops, vape pens, and tinctures that do not contain THC or contain it in lower amounts that will not cause a “high.” Hemp is not marijuana, however. It is a completely separate plant even though they are both cannabis varieties.

NIDA reports that other uses being explored include treatment of epilepsy, anxiety disorders, substance use disorders, schizophrenia, cancer, pain, inflammatory diseases, and acne, among other conditions. However, more research is needed to fully understand the effects and whether or not there are actual benefits for these conditions.

Marijuana Legalization in the States

As of October 2020, marijuana is fully legal in 22 states (see state-by-state breakdowns for recreational and medical use). Testing regulations and the amounts of possession legally allowed do vary by state.

In those states where marijuana is legally accessible, individuals with schizophrenia may be tempted to try it, either for social reasons or in some cases, to help them cope with symptoms – despite the risks that exist, Foster explains.

She points out that in Oregon, for instance, marijuana was legalized in 2016 for both medical and recreational purposes. Since then, she says she has seen “patients who were chronically mentally ill or have the propensity for mental illness (such as a family history of mental illness, stressful life events, and the use of drugs) become psychotic from using marijuana.”

Foster also explains that while some people may believe that marijuana with a lower THC:CBD ratio may be less likely to cause or exacerbate psychosis, the risk still exists, making it important that those with a tendency toward psychosis simply avoid marijuana completely.

“My first thought about schizophrenia and marijuana is that they are [at odds with one another],” Foster says. “Unless followed closely as a medication, I think marijuana could easily contribute to the delusions and hallucinations that come with schizophrenia. I have also not found any long-term supporting evidence that people with schizophrenia benefit from its use,” she adds.

Exploring the Risks of Marijuana

Marc Manseau, MD, MPH, a clinical assistant professor of pPsychiatry at the New York University School of Medicine and expert on the intersection between serious mental illness and substance use disorders, agrees that for people with schizophrenia and related diagnoses with a tendency toward psychosis, marijuana use may actually worsen problems, rather than relieving them. To understand the risks, you need to understand what psychosis really is, he says.

“Psychosis is a disruption in the brain’s perception, interpretation, and/or processing of reality. A healthy brain seamlessly filters useful bits of information from the irrelevant noise and constructs a ‘reality’ that allows us to function in the world. When someone is psychotic, however, the system goes awry and things that shouldn’t have any meaning take on special [out of context] importance,” Dr. Manseau explains, adding that the danger lies in the THC, which has psychotic properties.

Although some people mistakenly believe that medical marijuana does not contain levels of THC, thus making if “safer,” this usually isn’t the case, Dr. Manseau clarifies. In fact, there are no regulations as to what medical marijuana must contain, which can be dangerous for people with a tendency for psychosis.

Marijuana and Psychosis: A Troubling Connection

The risks and benefits of marijuana have been the subject of much research in recent years. In a literature review conducted by Dr. Manseau that appeared in Neurotherapeutics, he points out that a number of studies have found a clear association between frequent (once daily or more) use of cannabis at an early age (approximately 14 years old) and psychosis.

Dr. Manseau also cites specific factors that could increase the risk of developing a psychotic disorder following cannabis use. Factors include a family history of schizophrenia, past child abuse or neglect, and living in an urban environment during childhood. He also stresses that cannabis use in people with a schizophrenia diagnosis may also have more severe symptoms and lower functioning than their counterparts. On the flip side, he says that among people with psychosis, discontinuing cannabis use has also been found to improve mood and anxiety and reduce psychotic symptoms.

A separate review of a dozen studies that recently appeared in the Journal of Clinical Psychiatry found cannabis use was associated with poorer symptomatic outcomes in people who suffered from various anxiety and other mood disorders, including depression.

He also says that further complicating matters is that some research suggests there could be benefits from using CBD to treat psychosis. But at this point, he and his colleagues believe the risks outweigh any possible benefits. “This is certainly not yet definitive and doctors require much more solid evidence to recommend treatments to patients. So, it’s still too preliminary to even recommend CBD to anyone with schizophrenia,” he says.

To get more specific, “For people with schizophrenia, the high THC content [15-30% or even higher] on average in today’s weed is simply dangerous, since THC is known to increase the risk of psychosis,” Dr. Manseau stresses. He also says that some people believe that since they know marijuana with high THC is dangerous, they will just take more care with what they use [in terms of THC content].

Since medical marijuana is not regulated by the FDA—not even in states where it is legal – there is no guarantee that this won’t trigger a problem, Dr. Manseau says, adding, “All medical marijuana is likely to have at least some THC, and THC can increase the risk of developing and exacerbate psychosis.”

Modern Marijuana: Stronger Strains May Increase Risks

Further, for anyone tempted to try self-medicating with marijuana, both Foster and Dr. Manseau warn that what is available on the streets today is not the same as it was a few decades ago.

“Marijuana today is stronger [meaning it has a higher average THC content],” Foster says. Dr. Manseau points out that this is worrisome since other studies show that using high THC marijuana increases the risk of psychosis.

“Today’s marijuana may also be mixed with other things [including other drugs or substances that can increase the psychosis effect],” Foster adds. This makes it much more dangerous, especially for people who are susceptible to psychotic reactions. And because it’s not regulated, there’s simply no way to know.

Living with Schizophrenia: Understanding the Cannabis Pull

While most medical experts have studied the impact of cannabis on schizophrenia in others or have read the latest literature, Julie A. Fast, author of Loving Someone with Bipolar Disorder, Take Charge of Bipolar Disorder, Get it Done When You’re Depressed, Bipolar Happens! and The Health Cards Treatment System for Bipolar Disorder, brings a much deeper understanding of schizophrenia to the table. That’s because she has a similar diagnosis called schizoaffective disorder. “This means that I have bipolar disorder and a separate psychotic disorder. I do not have schizophrenia, but I share many of the symptoms when I get sick [with schizoaffective disorder],” she explains.

She draws on her experiences as a person living with a mental illness to assist mental health professionals. Due to her diagnosis, she’s able to provide an important perspective on what it’s like which also helps to engage patients in treatment and recovery. “My specialty is creating management plans for people who live with mood and psychotic disorders. I also do a lot of work in the anxiety and personality disorder world,” she says.

Since she has first-hand knowledge of what it feels like to be psychotic, her insights are particularly helpful in teaching doctors how to support their patients when they are experiencing an episode.

“When I am psychotic, it is incredibly uncomfortable. Nothing makes sense. I see people as dangers to myself and am not able to process information in a normal way. The senses are confused and life is chaotic,” Fast states.

“I also experience paranoia, which is my main delusion [or false belief]. In this state, I truly FEEL that people are following me or are out to get me. Delusions are [part of ] the reason schizophrenia is so hard to manage,” she says.

When someone is experiencing schizophrenia or psychosis, he or she is also eager for relief—that’s where the temptation of marijuana comes in. “It’s a rough and very disabling illness that has to be managed daily. It makes sense that people will hear about cannabis and think, ‘Hey, it’s used for anxiety. I have a lot of anxiety with my schizophrenia, I want to feel better, so I will try cannabis,’” Fast says.

But she knows most patients don’t understand the full risks. That’s where clinicians can help fill the gaps.

Using Medical Marijuana: How Patients Can Stay Safe

Here is a rundown of what Foster suggests to the patients she works with:

  • If you are going to use marijuana, it’s important to work with your psychiatrist and other trusted members of your mental health team who understand the dangers of THC on people vulnerable to experiencing psychosis and who can guide you in the best way.
  • Understand that even if something is labeled as low THC or no-THC, this doesn’t mean it’s true since marijuana is not currently approved by the Food and Drug Administration (FDA). The only way to know how it will impact you is to actually try it, which is not worth the risk if it could lead to psychosis.
  • Keep in mind that just because it’s called “medical marijuana” doesn’t mean that it’s safe, whether you are consuming it as a tincture, in plant form, as a topical product, or as an edible. “Medical marijuana” is simply a name. Only testing with your own body will let you know if something is safe. (Also keep in mind that there are several FDA-approved cannabis-based medications with very restricted indications including nausea, appetite stimulation, and epilepsy, but these are not medical marijuana.)

Support is also crucial. “I think the best way for people with schizophrenia to work through their ‘stormy passages’ of worsening delusions or hallucinations is to have a community of support that understands schizophrenia, a close relationship with their mental health providers, and a strong rhythm for their daily life,” says Foster. “We know that people who don’t have a support system, who do not trust their providers even when not psychotic, and who get out of healthy routines and lifestyles will flounder. While schizophrenia is a challenging illness to live with, with the right supports in place, one can still lead a happy, full, and successful life.”

Related Articles

Cannabis use for the management of ADHD, and more on medical marijuana for patients with PTSD

NIDA. Is Marijuana Safe and Effective as Medicine? Updated June 2018. Accessed 20 September 2018.

Mammen, G et al. “Association of Cannabis With Long-Term Clinical Symptoms in Anxiety and Mood Disorders: A Systematic Review of Prospective Studies.” J Clin Psychiatry. June 5, 2018. 79(4).

Iffland, Kirsten and Grotenhermen, Franjo. “An Update on Safety and Side Effects of Cannabidiol: A Review of Clinical Data and Relevant Animal Studies.” Cannabis Cannabinoid Res. June 21, 2017.

Volkow ND. The Biology and Potential Therapeutic Effects of Cannabidiol. Presented at Drug Caucus Hearing on Barriers to Cannabidiol Research. June 24, 2015.

Manseau M. For an unlucky few marijuana isn’t so chill. Medium. Oct. 17, 2017.

Manseau, M, Goff DC. “Cannabinoids and Schizophrenia: Risks and Therapeutic Potential.” Neurotherapeutics (2015) 12: 816-824.

Matthews S. Smoking cannabis just 5 TIMES as a teenager raises the risk of psychosis, reveals ‘worrying’ study. Accessed online April 20, 2018.

“Patients and Families: Schizophrenia.” American Psychiatric Association. January 2017. Available at:

“Schizophrenia.” Mayo Clinic. Available at: Accessed May 2, 2018.

Szalavitz M. Marijuana Compound Treats Schizophrenia with Few Side Effects: Clinical Trial.” Time. May 30, 2012.

Vadhan NP et al Acute effects of smoked marijuana in marijuana smokers at clinical high-risk for psychosis: A preliminary study. Psychiatry Res. 2017; 257: 372.

Whether cannabis can positively impact schizophrenia is not fully understood but experts point to a dangerous link between THC and psychosis.