Cannabis Hyperemesis Syndrome (CHS)
A paradoxical syndrome of cyclic vomiting in chronic cannabis users that resolves only with cessation.
CHS is real, it's increasingly common, and it's one of the few places where the 'cannabis is harmless' narrative breaks down hard. The hot-shower thing isn't folklore — it's a documented diagnostic clue, though nobody fully understands why it works. The only proven cure is stopping cannabis entirely. Capsaicin cream and haloperidol have decent evidence for acute episodes; standard anti-nausea drugs like ondansetron mostly don't work. If you're vomiting cyclically and using cannabis daily, this is probably why.
Not Medical Advice
This article is educational, not medical advice. If you are vomiting repeatedly, unable to keep fluids down, or experiencing severe abdominal pain, seek medical care. CHS can cause dangerous dehydration, electrolyte disturbances (including hypokalemia and acute kidney injury), and has been associated with rare deaths [1]. Talk to a clinician before changing treatment for any condition.
Plain-Language Summary
Cannabis hyperemesis syndrome is a paradox: cannabis is widely used (and FDA-approved in synthetic forms like dronabinol) to treat nausea, yet in a subset of heavy chronic users it causes severe cyclic vomiting. The syndrome was first formally described in 2004 by Allen and colleagues in South Australia, who reported nine chronic cannabis users with cyclic vomiting that resolved on cessation and recurred on resumption [2].
CHS typically progresses through three phases [3]:
- Prodromal phase: morning nausea, abdominal discomfort, fear of vomiting — sometimes for months or years.
- Hyperemetic phase: intense, repeated vomiting (often 5+ times per hour), abdominal pain, and the hallmark compulsive hot bathing or showering, which transiently relieves symptoms.
- Recovery phase: symptoms resolve over days to weeks after stopping cannabis.
The diagnostic clue most clinicians rely on is the hot-shower behavior combined with daily cannabis use for at least a year [3][4]. There is no specific lab test.
What Probably Works
Cannabis cessation is the only intervention with consistent evidence for long-term resolution Strong evidence. Across case series and cohort studies, patients who fully stop using cannabis stop having episodes; those who resume relapse [2][3][5].
IV fluid resuscitation is standard supportive care for the dehydration and electrolyte derangements that accompany acute episodes Strong evidence — this is general emergency medicine, not CHS-specific.
Topical capsaicin cream (0.025%–0.1%) applied to the abdomen or back has emerged as a reasonable acute-phase option [evidence:weak-to-moderate]. A 2019 systematic review found multiple case reports and small studies suggesting benefit, plausibly via TRPV1 receptor activation that mimics the heat-shower effect [6]. A 2022 randomized trial (Dean et al.) found capsaicin non-inferior to ondansetron but did not show clear superiority over placebo in all endpoints [7].
Haloperidol (a dopamine antagonist) has the best ED evidence of any pharmacologic agent. A 2021 randomized controlled trial (Ruberto et al.) compared haloperidol to ondansetron in 33 ED patients and found haloperidol superior for both pain and nausea reduction [evidence:weak-to-moderate, single small RCT][8].
What Might Work
Benzodiazepines (lorazepam) are commonly used in EDs and reported in case series to provide symptom relief, possibly via anxiolysis and central antiemetic effect Weak / limited[3]. No high-quality RCT exists.
Droperidol, another dopamine antagonist, is used similarly to haloperidol with comparable mechanism, but specific CHS evidence is limited to case reports Weak / limited.
Hot showers/baths reliably abort symptoms during an episode and are diagnostically important, but they are not a treatment — they don't change the underlying course and prolonged hot bathing has caused burns in some patients [evidence:anecdote-to-weak][3].
Cognitive behavioral therapy and motivational interviewing to support cessation are reasonable based on general addiction-medicine evidence, but CHS-specific trials are absent [evidence:none for CHS specifically].
What Doesn't Work or Has Weak Evidence
Ondansetron (Zofran) — the workhorse antiemetic for chemotherapy and gastroenteritis — performs poorly in CHS. Multiple studies and the Ruberto RCT show limited efficacy [evidence:weak / mostly negative][8].
Metoclopramide and promethazine are similarly underwhelming in case series Weak / limited.
Opioids are commonly given for the abdominal pain but do not address the underlying syndrome and risk worsening nausea and dependency [evidence:weak / avoid when possible].
Proton pump inhibitors and standard GI workups (endoscopy, imaging) typically come back unremarkable — CHS is a clinical diagnosis, not one made by ruling things in [3].
Continuing cannabis but switching strains, going to CBD-dominant products, or reducing dose — patients frequently try this and report online that it helps. Published evidence does not support partial reduction as a reliable strategy; relapse on resumption is the dominant pattern [evidence:anecdote, contradicted by case series][2][5].
What We Don't Know
The mechanism of CHS is genuinely unclear. Leading hypotheses include [3][9]:
- Downregulation or dysfunction of CB1 receptors in the gut versus the brain (different effects in different compartments).
- TRPV1 desensitization (why heat helps, why capsaicin helps).
- Genetic variation in cannabinoid metabolism — a 2020 study (Russo et al.) identified candidate variants in COMT, TRPV1, CYP2C9, and others, but findings are preliminary [10].
We don't know:
- Why only some heavy users develop CHS while most do not.
- Whether high-THC concentrates increase risk beyond flower (suspected but not well quantified).
- The true incidence — most estimates come from ED populations and likely undercount mild cases.
- Whether CBD, terpene profile, or specific cultivars matter — claims here are essentially No data.
- Long-term GI consequences after recovery.
There is no validated diagnostic biomarker. Diagnosis remains clinical and largely one of exclusion.
Comparison with Standard Treatments for Cyclic Vomiting
CHS clinically resembles cyclic vomiting syndrome (CVS), and the two are often confused. Key differences [3][11]:
| Feature | CHS | CVS (idiopathic) | |---|---|---| | Cannabis use | Daily/near-daily, chronic | Variable | | Hot bathing relief | Characteristic | Less typical | | Tricyclic antidepressants (amitriptyline) | Limited evidence | First-line prophylaxis with reasonable evidence | | Resolution with cannabis cessation | Yes | No |
A practical problem: many patients diagnosed with CVS who also use cannabis may actually have CHS, and standard CVS prophylaxis (amitriptyline, topiramate) will fail until cannabis is stopped. Conversely, telling every cyclic-vomiting cannabis user they have CHS risks missing real CVS, gastroparesis, or other diagnoses.
Risks and Complications
Documented complications include [1][3]:
- Severe dehydration and acute kidney injury ("cannabinoid hyperemesis acute renal failure" has its own small literature).
- Hypokalemia and other electrolyte disturbances, with rare cardiac arrhythmias.
- Burns from compulsive hot bathing.
- Dental erosion from repeated vomiting.
- Mallory-Weiss tears and esophagitis.
- Death — rare but reported, usually from electrolyte/dehydration complications [1].
The syndrome is reversible. The challenge is that cessation is hard: many patients have used cannabis for years, often for symptoms (anxiety, pain) that will return when they stop. A harm-reduction conversation that acknowledges this — rather than a moralizing one — tends to work better.
See also: Cannabis Use Disorder, Dronabinol, THC.
Sources
- Reported Nourbakhsh M, Miller A, Gofton J, et al. Cannabinoid hyperemesis syndrome: reports of fatal cases. Journal of Forensic Sciences, 2019; 64(1): 270-274.
- Peer-reviewed Allen JH, de Moore GM, Heddle R, Twartz JC. Cannabinoid hyperemesis: cyclical hyperemesis in association with chronic cannabis abuse. Gut, 2004; 53(11): 1566-1570.
- Peer-reviewed Sorensen CJ, DeSanto K, Borgelt L, Phillips KT, Monte AA. Cannabinoid hyperemesis syndrome: diagnosis, pathophysiology, and treatment—a systematic review. Journal of Medical Toxicology, 2017; 13(1): 71-87.
- Peer-reviewed Simonetto DA, Oxentenko AS, Herman ML, Szostek JH. Cannabinoid hyperemesis: a case series of 98 patients. Mayo Clinic Proceedings, 2012; 87(2): 114-119.
- Peer-reviewed Habboushe J, Rubin A, Liu H, Hoffman RS. The prevalence of cannabinoid hyperemesis syndrome among regular marijuana smokers in an urban public hospital. Basic & Clinical Pharmacology & Toxicology, 2018; 122(6): 660-662.
- Peer-reviewed Richards JR, Lapoint JM, Burillo-Putze G. Cannabinoid hyperemesis syndrome: potential mechanisms for the benefit of capsaicin and hot water hydrotherapy in treatment. Clinical Toxicology, 2018; 56(1): 15-24.
- Peer-reviewed Dean DJ, Sabagha N, Rose K, et al. A pilot trial of topical capsaicin cream for treatment of cannabinoid hyperemesis syndrome. Academic Emergency Medicine, 2020; 27(11): 1166-1172.
- Peer-reviewed Ruberto AJ, Sivilotti MLA, Forrester S, et al. Intravenous haloperidol versus ondansetron for cannabis hyperemesis syndrome (HaVOC): a randomized, controlled trial. Annals of Emergency Medicine, 2021; 77(6): 613-619.
- Peer-reviewed Galli JA, Sawaya RA, Friedenberg FK. Cannabinoid hyperemesis syndrome. Current Drug Abuse Reviews, 2011; 4(4): 241-249.
- Peer-reviewed Russo EB, Spooner C, May L, Leslie R, Whiteley VL. Cannabinoid hyperemesis syndrome survey and genomic investigation. Cannabis and Cannabinoid Research, 2022; 7(3): 336-344.
- Peer-reviewed Venkatesan T, Levinthal DJ, Tarbell SE, et al. Guidelines on management of cyclic vomiting syndrome in adults by the American Neurogastroenterology and Motility Society. Neurogastroenterology & Motility, 2019; 31 Suppl 2: e13604.
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