Cannabinoid Hyperemesis Syndrome (CHS) is one of the most widely misunderstood conditions in the cannabis world. Despite years of research and thousands of documented cases, most consumers — and even many healthcare providers — still struggle to understand what CHS is, why it happens, how common it truly is, and what can be done about it.

CHS is real. It is unpleasant. But it is also very rare, highly specific, and overwhelmingly concentrated among a particular type of cannabis consumer: long-term, daily, heavy users.

This article is designed to be the definitive, evergreen explainer — medically accurate, easy to understand, and grounded in real data rather than sensationalism. Whether you’re a consumer, patient, clinician, or educator, this guide will help you understand the science of CHS without the stigma, fear, or misinformation that often surrounds it.

1. What Exactly Is Cannabinoid Hyperemesis Syndrome?

CHS is a condition characterized by cycles of severe nausea, vomiting, and abdominal pain in people with long-term, heavy cannabis use. Symptoms typically occur in episodes, often lasting 24–72 hours, with symptom-free periods in between.

What makes CHS unique — and medically identifiable — is that symptoms reliably improve when cannabis use stops, and they frequently return when heavy use resumes.

CHS was first described in the medical literature in 2004 in a group of long-term cannabis users in Australia. Since then, it has been confirmed in multiple countries and populations, and as of 2025, it has its own diagnostic code in the International Classification of Diseases (ICD-10-CM R11.16), meaning clinicians can formally identify and track the condition.

2. Symptoms and Phases of CHS

CHS typically appears in three distinct phases, a pattern recognized across clinical studies and emergency medicine guidelines.

Prodromal Phase

• Morning nausea

• Abdominal discomfort

• Decreased appetite

• Anxiety around eating

• Continued cannabis use despite symptoms

This phase can last months or even years before full CHS episodes begin.

Hyperemetic Phase

This is the stage most people associate with CHS.

Common features include:

• Repeated vomiting (sometimes dozens of times per day)

• Severe abdominal pain or cramping

• Dehydration, dizziness, or faintness

• Temporary relief from very hot showers or baths

The hot-shower behavior is considered a hallmark symptom because many CHS patients discover this instinctively, before ever learning the name of the condition. Relief occurs due to activation of the TRPV1 heat receptors, which temporarily modulate nausea signals.

Recovery Phase

• Symptoms resolve after stopping cannabis

• Appetite and digestion return to normal

• Energy levels improve

If heavy cannabis use is resumed, symptoms often return — sometimes within days, sometimes after weeks or months.

3. How Common Is CHS? (Real Data, Not Guesswork)

This is the most important — and most misunderstood — part of the conversation.
CHS is not remotely common among the general cannabis-using population.

We can break the data into two key categories:

CHS Among All Cannabis Consumers

Across multiple studies, including ER datasets, reviews, and clinical analyses, researchers estimate that CHS affects between 0.084% and 0.12% of all cannabis consumers.

In simpler terms:

• About 1 in 1,000 cannabis users may experience CHS

• 99.9% of users will never develop it

That’s even among populations with increasing cannabis use.

CHS Among Heavy, Long-Term Daily Users

CHS is heavily concentrated among:

• People who use it daily or multiple times per day

• Often for years

• Often with high-THC products, especially concentrates

Even among heavy daily consumers, CHS remains uncommon:

• Best estimates: 0.7% to 1.0%

Meaning:

• Roughly 1 in 100 long-term daily users may experience CHS

• And 99+ out of 100 will not

Emergency Room Data

Large studies using national ER databases show:

• CHS makes up a very small fraction of total ER visits

• Younger adults (18–35) are the majority of documented cases

• Most patients were long-term daily users

Even with increasing recognition, CHS visits account for well under 0.2% of all emergency department traffic.

Bottom line:

CHS is real but rare, and the overwhelming majority of cannabis users — including most daily users — will never experience it.

4. Who Is Most at Risk?

While CHS can occur at different ages and across various demographics, clinical patterns are extremely consistent. People most at risk typically fit the following profile:

• Daily or near-daily cannabis use

• Multiple years of frequent consumption

• Preference for high-THC products, especially dabs and concentrates

• Onset often in late teens or 20s

• Frequently meets criteria for cannabis use disorder (CUD)

• Finds relief through hot bathing, a hallmark sign

CHS is not associated with:

• Casual or occasional use

• CBD-only products

• New or inexperienced users

• Medical patients using moderate doses

It is a heavy-use, long-term exposure effect — not an allergic reaction, not poisoning, and not caused by casual, recreational use.

5. Why Does CHS Happen? (What Science Understands So Far)

This is the area of greatest scientific debate because no single mechanism fully explains CHS. However, several leading theories have strong support.

A. Endocannabinoid System Overload

Chronic high-dose THC may disrupt the natural endocannabinoid signaling system in the brain and gut.
Overstimulation of CB1 receptors could paradoxically trigger nausea and vomiting, the opposite of THC’s usual effects.

B. Gut–Brain Axis Dysregulation

Newer research classifies CHS as a disorder of gut-brain interaction.
Cannabinoids affect digestion, gastric emptying, and gut motility — long-term overstimulation may disrupt these systems.

C. TRPV1 Heat Receptor Involvement

This is why hot showers feel good.

• TRPV1 receptors respond to heat and capsaicin.

• Stimulating them temporarily modulates the vomiting pathways.

D. Cannabinoid Accumulation in Fat Tissue

THC is stored in fat cells and released slowly over time.
Some researchers believe this persistent exposure pushes susceptible individuals toward CHS episodes.

E. Genetic Susceptibility

Studies point to possible genetic polymorphisms that may make some individuals far more vulnerable than others.

Important note:

None of these theories alone explains 100% of cases.
CHS is real, but the exact “why” is still under active investigation.

6. How CHS Is Diagnosed

There is no blood test or imaging scan for CHS.
Diagnosis is clinical — based on patterns, symptoms, and history.

Most clinicians use criteria similar to the AGA (American Gastroenterological Association):

• Long-term cannabis use

• Cyclical vomiting with symptom-free intervals

• Abdominal pain

• Relief from hot showers/baths

• Improvement after stopping cannabis

• Exclusion of other causes

The biggest challenge is that many patients suffer for years before being correctly diagnosed because:

• Patients often don’t link symptoms to cannabis

• Doctors often don’t ask about cannabis

• Symptoms mimic many other gastrointestinal conditions

On average, diagnosis can take 3 to 6 years.

7. Treatment: What Actually Works

This part is simple, direct, and medically unambiguous.

Acute (Short-Term) Treatment in the ER

• IV fluids

• Electrolyte replacement

• Antiemetics (though many are only partly effective)

• Sometimes haloperidol or other dopamine-blocking medications

• Topical capsaicin cream

• Hot showers or baths

These help manage the episode — they do not cure CHS.

Long-Term Treatment

There is only one treatment proven to be consistently effective:

Stop cannabis use.

Not cut back.
Not switch strains.
Do not use CBD instead of THC.

Total cessation is the only intervention that reliably ends CHS.

Once cannabis is discontinued, symptoms typically resolve within days to weeks.
If heavy use resumes, symptoms often return — sometimes more quickly and more severely.

It is no different than a food intolerance or allergy:
If something makes you violently ill every time you consume it, the only rational long-term solution is to stop consuming it.

8. CHS vs. Contaminants, Pesticides, or Synthetic Cannabinoids

This is a popular topic and worth addressing clearly.

What evidence supports:

• CHS occurs in legal and illegal markets, in medical markets, across multiple countries, and over decades.

• CHS has been documented in users who smoke flower only — not just extracts or vape carts.

• Contaminants can absolutely cause nausea and vomiting, but they do not explain the distinctive CHS pattern.

What evidence does not support:

• Pesticides cause that CHS

• That CHS is caused by mold or contaminants

• That it only happens with concentrates

• That it only happens with “modern weed”

Contaminants can mimic CHS, but they are not the primary driver of true CHS.

9. Harm Reduction for Cannabis Consumers

You don’t need Reefer Madness.
You don’t need to panic.
You just need honest, evidence-based guidance.

If you use cannabis heavily:

• Be mindful of increasing tolerance

• Take occasional tolerance breaks

• Use tested, regulated products when possible

• Be cautious with very high-THC concentrates

If you experience repeated vomiting episodes:

• Pay attention to patterns

• Notice whether hot showers relieve symptoms

• Do not ignore repeated, unexplained nausea

• Speak with a healthcare professional

• Consider stopping cannabis for several weeks to confirm or rule out CHS

If you are diagnosed with CHS:

• The solution is simple but not always easy: stop using cannabis

• Symptoms will almost always disappear

• Returning to heavy use will almost always bring them back

Conclusion

Cannabinoid Hyperemesis Syndrome is a real, clinically recognized condition — but also a highly specific and very rare one. The overwhelming majority of cannabis consumers will never experience it, and even among daily users, only a small percentage are at risk.

Understanding CHS is not about fear — it’s about empowerment and harm reduction.
If you know the signs, understand the mechanisms, and listen to your body, you can make informed, healthy decisions about your cannabis use.

This guide is designed to be a long-term, medically grounded resource for anyone seeking clarity, science, and truth — not sensationalism.

Do you or anyone you know suffer from CHS? Please let us know in the comments; we’d love to know.