Should we prescribe medical cannabis to treat withdrawal symptoms in people admitted to psychiatric hospitals?
A study by Dr Aliyah Malik and colleagues suggests that people who suddenly stop using cannabis when going into hospital for a mental health problem and are at greater risk of declining a few days after admission.
The brief report published in JAMA Psychiatry in June this year found that cannabis users are more likely to be transferred to a psychiatric intensive care unit (PICU) after being admitted to the general psychiatric ward of a hospital.(1) This was especially true in on the 3rd, 4th and 5th day after being admitted to hospital – the time when you can expect cannabis withdrawal symptoms to be at their worst.
What is a PICU?
A psychiatric intensive care unit, or PICU, is a specialist ward that has more intensive care compared to general psychiatric wards. These wards have more staff are assigned to each patient and stricter security measures in place. People with severe mental health problems may need to spend time in a PICU if they have especially distressing and hard-to-treat behaviours, typically violence and aggression, that could put themselves or other people at risk in a general ward.
What is cannabis withdrawal?
A proportion of people who use cannabis heavily will develop withdrawal symptoms when they stop. Possible symptoms include irritability, anxiety, sleep problems, decreased appetite, depressed mood and physical symptoms such as headaches, stomach cramps, shaking and sweating.(2) Symptoms typically start 1-2 days after stopping cannabis, peak on days 2-6 and end after 1-3 weeks. Generally, the more cannabis a person uses and the more often they use it, the worse the withdrawal symptoms and the longer they last.(3) Recently, cannabis withdrawal has been linked to relapsing of symptoms in people with psychotic disorders.(4) This could mean that people with severe mental health problems, such as schizophrenia, who suddenly stop using cannabis due to going into hospital could be particularly vulnerable to the effects of cannabis withdrawal.
What did this study find?
The study conducted by Dr Malik and colleagues looked at data from all the people who had been admitted to one of 4 psychiatric hospitals in London, UK, between January 1st, 2008 and December 31st, 2023 (skipping March 26th, 2020 to April 26th, 2022 due to the COVID-19 pandemic). Overall, 47.2% of the 52,088 people admitted were current cannabis users.
Between 3-5 days after being admitted to hospital, when cannabis withdrawal symptoms would be expected, cannabis users were 41% more likely to be transferred to a PICU than non-users. Controlling for other factors such as age, sex, ethnicity, and other drug and alcohol use reduced this to 36%, which is still a significant increase in risk. Certain population groups were particularly vulnerable; women who used cannabis were twice as likely to be admitted to a PICU on days 3-5 than women who didn’t use cannabis. And being over 35 and using cannabis increased the risk of PICU treatment 2.5x on compared to non-users in the same age group.
Another explanation for these results could be the self-medication hypothesis – the idea that people are using cannabis to help manage their symptoms and then deteriorate when it is taken away. However, while most clinical studies have found that cannabis can lead to temporary mood improvement and less negative symptoms (e.g., speaking less, lack of motivation, feeling unable to experience pleasure, having fewer social interactions), it also tends to make positive symptoms of psychosis worse (e.g., hallucinations, delusions, disorganised thinking, erratic or agitated behaviour), and it is generally the positive symptoms that lead to a person requiring transfer to a PICU.(5) That being said, there is also evidence, such as from case studies, that a minority of people with psychosis do in fact improve while using cannabis,(6) showing the complexity of the interactions between cannabis and mental health.
While this research study wasn’t able to directly measure cannabis withdrawal symptoms, by focussing on the specific time period when cannabis withdrawal symptoms peak, they were able to make a significant association with needing more aggressive care. But how can we reduce this burden for patients?
What’s next?
There are currently no medicines approved for treating cannabis withdrawal. One possibility could be replacement therapy, similar to nicotine replacement for tobacco withdrawal. There have been multiple studies on treating cannabis withdrawal with cannabis receptor agonists (i.e., cannabis-derivatives and drugs that act on the brain like cannabis) (7), and there have been some examples of people using these off-label.(3) However, no clinical trials of cannabis replacement therapy have been conducted in people with severe mental health problems. In addition, the adverse effects of such treatments would likely be worse in people with psychiatric disorders, with multiple studies showing that people with mental health conditions like schizophrenia experience worsening symptoms with cannabis use.(8, 9)
The authors conclude that future research should focus on finding safe and effective treatments for cannabis withdrawal that are suitable for people with severe mental health disorders. In the meantime, clinicians working with people in acute psychiatric care should be mindful of the possibility of cannabis withdrawal.
Article by Lucy Chester
References
- Malik A, Shetty H, Oliver D, Reilly TJ, Di Forti M, McGuire P, et al. Cannabis Withdrawal and Psychiatric Intensive Care. JAMA Psychiatry. 2025.
- American Psychiatric Association. Diagnostic and Statistical Manual of Mental Disorders. 5th ed. Arlington, VA2013.
- Connor JP, Stjepanović D, Budney AJ, Le Foll B, Hall WD. Clinical management of cannabis withdrawal. Addiction. 2022;117(7):2075-95.
- Chesney E, Reilly TJ, Scott F, Slimani I, Sarma A, Kornblum D, et al. Psychosis associated with cannabis withdrawal: systematic review and case series. The British Journal of Psychiatry. 2024:1-12.
- Schwarcz G, Karajgi B, McCarthy R. Synthetic Δ-9-Tetrahydrocannabinol (Dronabinol) Can Improve the Symptoms of Schizophrenia. Journal of Clinical Psychopharmacology. 2009;29(3).
- Henquet C, van Os J, Kuepper R, Delespaul P, Smits M, Campo JÀ, et al. Psychosis reactivity to cannabis use in daily life: an experience sampling study. British Journal of Psychiatry. 2010;196(6):447-53.
- Werneck MA, Kortas GT, de Andrade AG, Castaldelli-Maia JM. A Systematic Review of the Efficacy of Cannabinoid Agonist Replacement Therapy for Cannabis Withdrawal Symptoms. CNS Drugs. 2018;32(12):1113-29.
- Sideli L, Quigley H, La Cascia C, Murray RM. Cannabis Use and the Risk for Psychosis and Affective Disorders. Journal of Dual Diagnosis. 2020;16:22-42.