Cannabinoid Hyperemesis Syndrome (CHS)

What CHS is

Cannabis is often used to reduce nausea, so it seems paradoxical that it can cause vomiting. In CHS, long-term heavy exposure to THC appears to change how cannabinoid receptors in the brain and gut work, disrupting the body's control of nausea, gut movement and temperature. Higher-potency products and concentrates (dabs, vapes) are linked to rising numbers of cases.

The three phases of CHS

1. Prodromal phase: months to years of morning nausea, fear of vomiting and belly discomfort. Eating patterns stay mostly normal. Many people increase cannabis use believing it helps the nausea.
2. Hyperemetic phase: episodes of intense, repeated vomiting and retching, often many times an hour, with belly pain, dehydration and weight loss. People take frequent hot showers or baths for relief. Episodes last from 24 to 48 hours up to a week or more.
3. Recovery phase: after stopping cannabis, vomiting settles and eating returns to normal over days to weeks. Symptoms return if cannabis is used again, sometimes even after months of abstinence.

Symptoms

• severe, repeated nausea and vomiting, often worse in the morning
• diffuse belly pain
• compulsive hot showers or baths for relief
• reduced appetite and weight loss
• signs of dehydration: thirst, dark urine, dizziness

Diagnosis

There is no single test. Doctors base the diagnosis on:

• Rome IV criteria: stereotyped episodes of vomiting resembling cyclic vomiting syndrome, after prolonged excessive cannabis use, with relief after sustained cessation
• cannabis use history: most people use daily or more than 4 times a week for over a year
• hot shower relief, which strongly supports the diagnosis
• tests to rule out other causes: blood tests (electrolytes, kidney and liver function, lipase), urine tests, pregnancy test, and sometimes imaging or endoscopy

Because it is easily missed, many people undergo multiple scans and ER visits before diagnosis. Being honest about cannabis use speeds up the right treatment.

CHS vs cyclic vomiting syndrome

Cyclic vomiting syndrome causes identical vomiting episodes, and hot shower relief can occur in both. The difference is that CHS is linked to heavy cannabis use and resolves when cannabis stops. Doctors often confirm CHS when symptoms disappear after at least 6 months without cannabis.

Treatment

In the emergency department

• Intravenous fluids to correct dehydration, and replacement of potassium and other electrolytes
• Haloperidol or droperidol: antipsychotic medicines that often work when usual anti-nausea medicines fail
• Topical capsaicin cream on the belly, which may mimic the effect of hot water
• Benzodiazepines for severe nausea and agitation
• Avoiding opioids, which can worsen nausea and gut slowing
• checking for acute kidney injury and other complications

Long-term treatment: stopping cannabis

Complete abstinence is the only proven cure. Reducing use or switching products usually does not stop the episodes.

• Symptoms typically improve within days to 2 weeks of stopping, though full recovery can take months.
• Cannabis withdrawal symptoms, such as irritability, poor sleep, anxiety and low appetite, peak in the first week and fade within 2 to 4 weeks.
• Support helps: cognitive behavioral therapy, motivational interviewing, peer support groups, and treatment for anxiety, depression or sleep problems that cannabis was used to manage.
• See cannabis use disorder for treatment options.

Home measures during an episode

• Sip small amounts of clear fluids or oral rehydration solution.
• Warm showers may help, but avoid very hot water, which can cause burns and worsen dehydration.
• Rest in a cool, quiet place.
• Seek care if you cannot keep fluids down.

Complications

• dehydration and low potassium, sodium or chloride
• acute kidney injury
• tears in the esophagus from forceful vomiting (Mallory-Weiss tears)
• tooth erosion from stomach acid
• burns from scalding showers
• rarely, heart rhythm problems, seizures or death from severe electrolyte imbalance

Frequently asked questions

What are the symptoms of cannabinoid hyperemesis syndrome?

The main symptoms are repeated episodes of severe nausea and vomiting, belly pain, and a strong urge to take hot showers or baths, which temporarily relieve symptoms. Episodes happen in people who use cannabis regularly, usually daily, for a long time.

How long does CHS last?

An acute vomiting episode usually lasts 24 to 48 hours but can last a week or more. After stopping cannabis completely, most people improve within days to 2 weeks, with full recovery over weeks to months. Symptoms often return if cannabis is used again.

Why do hot showers help CHS?

The reason is not fully understood. Heat may activate receptors in the skin (TRPV1) that affect nausea signaling, or help reset the brain's temperature and nausea control centers disrupted by cannabis. Capsaicin cream, which activates the same receptors, may help for similar reasons.

Can you get CHS from vaping or edibles?

Yes. CHS is linked to the amount and frequency of THC exposure, not the method. Smoking, vaping, dabbing concentrates and edibles can all cause it. High-potency products may raise the risk.

Can CHS be cured?

Yes. Stopping all cannabis use cures CHS in nearly everyone. Anti-nausea treatments only help during episodes. Many people need support to stop, and therapy and peer groups make success more likely.