The Hidden Condition Sending Young Cannabis Users to the ER — and Why Most Clinicians Miss It

As cannabis potency climbs to record levels and youth use rises across Canada, emergency departments are reporting a sharp increase in a condition most clinicians have never heard of — and that many young patients don’t know they have.

Cannabis hyperemesis syndrome (CHS) — defined by relentless cycles of vomiting, severe abdominal cramping and an unusual but characteristic compulsion to seek relief in scalding hot showers or baths — is hitting a population that’s particularly vulnerable: teenagers and young adults. And it’s doing so largely in silence, because the condition is widely misunderstood and frequently misidentified.

Jamie Seabrook and Jason Gilliland, public health researchers at Western University and co-authors of a newly published review on CHS in youth, argue that the condition is at a critical inflection point — one that requires immediate attention from clinicians, public health officials, and educators alike.

Youth cannabis use in Canada: a growing concern

Canada consistently ranks among the countries with the highest rates of youth cannabis consumption. Around 43 percent of young people between 16 and 19 reported using cannabis in the past year. That figure climbs even higher for those aged 20 to 24, where nearly half — about 48 percent — reported recent use.

This surge in consumption runs parallel to a dramatic increase in the potency of available products. Since the 1980s, average THC concentrations have risen by roughly 400 percent. Strains containing 25 percent THC or more are now routinely available. The combination of wider access and greater potency is creating the conditions for CHS to flourish — a syndrome that was virtually unknown before its first description in medical literature in 2004.

What actually happens during a CHS episode

CHS progresses through three recognizable stages:

• Early (prodromal) phase: The person begins experiencing morning nausea and mild abdominal discomfort. Believing cannabis relieves nausea, many increase their consumption — which worsens the underlying problem.
• Acute (hyperemetic) phase: Intense, prolonged vomiting sets in, accompanied by dehydration and abdominal pain. A distinctive feature of this phase is that patients find temporary relief through hot showers or baths — sometimes spending hours in them. This behavior is a key diagnostic indicator, though it is still frequently overlooked.
• Recovery phase: Symptoms fully resolve once the person stops using cannabis entirely. Return to use typically triggers a new cycle.

Despite these clear patterns, diagnosis is often significantly delayed. CHS mimics other gastrointestinal conditions, such as gastroenteritis or gastroparesis, leading physicians to order expensive CT scans, MRIs and gastric emptying studies before the real cause is identified. The compulsive hot-bathing behavior — one of the most reliable signs — is often not discussed or not asked about during clinical encounters.

Why young people face a higher risk

The adolescent and young adult brain is still actively developing until approximately age 25. Repeated THC exposure during this developmental window has been linked to impairments in memory, learning capacity and emotional regulation. Heavy cannabis use during these years is also associated with elevated risks of anxiety disorders, depression, psychosis and self-harm.

A troubling pattern identified by the researchers involves youth who turn to cannabis as a form of self-medication for existing mental health challenges. When CHS symptoms emerge, they often increase their intake — mistakenly thinking cannabis is helping rather than causing the problem. Additionally, fear of judgment, social stigma or concerns about legal consequences frequently prevent young patients from being honest with healthcare providers about their cannabis use.

The researchers also found that CHS is routinely confused with bulimia nervosa, given the shared features of repeated vomiting and unintended weight loss. The distinction, however, is important: in CHS, vomiting is entirely involuntary and has nothing to do with body image. A useful differentiating clue is that CHS patients typically return to normal eating and bathing habits during symptom-free intervals — a pattern not seen in eating disorders.

The strain on healthcare and the limits of current treatment

The burden of CHS extends well beyond the individual. Emergency department visits linked to the syndrome have climbed steeply in recent years. A study conducted in Ontario found a substantial spike in CHS-related ER admissions following the commercialization of cannabis after legalization in 2018. Repeated hospital visits, lost school days, missed work and significant emotional distress compound the impact on patients and families.

Standard anti-nausea medications — such as ondansetron — regularly prove ineffective against CHS. Some studies point to limited short-term relief from topical capsaicin application or low-dose haloperidol, but no acute treatment delivers consistent results. The only reliably effective intervention is complete cessation of cannabis use.

For youth who have been using cannabis to manage anxiety or other mental health conditions, stopping abruptly can trigger withdrawal symptoms and intensify distress. The researchers emphasize that harm reduction approaches — graduated reduction plans, concurrent mental health support and non-judgmental provider communication — are essential in these cases.

What needs to change

Seabrook and Gilliland call for clinicians to routinely screen young patients presenting with cyclic vomiting for cannabis use and hot-bathing behavior. Research indicates that youth are significantly more likely to disclose cannabis use when providers approach the conversation with empathy and without stigma.

On the public health side, the researchers advocate for honest, accessible education about CHS — delivered in schools, clinics and digital spaces — explaining what the condition is, how to recognize it and where to seek support. They argue that integrating CHS into youth health curricula, pediatric training programs and cannabis screening tools is long overdue.

“CHS is a preventable but growing consequence of chronic cannabis use in young people,” the authors write. As legal access continues to reshape social norms around cannabis, ensuring that both young people and their caregivers have accurate information about the full range of health risks is not optional — it is essential.

This article is based on expert commentary originally published by Western University News and co-authored by Jamie Seabrook (Professor, Departments of Epidemiology & Biostatistics and Paediatrics, Western University), Jason Gilliland (Professor, Geography & Environment, Western University) and Morgan Seabrook (undergraduate research assistant, Human Environments Analysis Laboratory). Republished under Creative Commons license via The Conversation. June 11, 2025.