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Cannabis hyperemesis syndrome
Regular and long-term use of cannabis (marijuana) and synthetic cannabis can cause ongoing nausea (feeling sick), repeated vomiting and stomach pains. This condition is known as cannabis hyperemesis syndrome (CHS).
CHS can be a serious condition. The only treatment is to completely stop using cannabis.
Causes of CHS
The exact causes are not known. But in some people, the long-term use of cannabis effects receptors in their gut causing nausea and vomiting. Receptors are specialised groups of cells that detect a stimulus and send signals to your brain.
CHS can happen if you have used cannabis at least weekly for several years. It is more common if you have used cannabis since you were a rangatahi (teenager).
CHS can happen with any type of cannabis use – smoking, inhaling or eating.
Symptoms of CHS
To start with, you may have:
- nausea, especially in the morning
- stomach pains
- a fear of vomiting.
This phase can last for weeks, months or years.
Later you may develop:
- stomach pain that can be severe
- more constant nausea
- bouts of frequent vomiting that last 1 to 2 days
- a loss of appetite and weight loss
- dehydration.
Severe symptoms may only last for 1 to 2 days. But they will come back if you use cannabis again.
Diagnosing CHS
Repeated vomiting has many possible causes.
If you have symptoms of CHS, you will need to tell your healthcare provider about your cannabis use to help them decide if this is the cause.
Your healthcare provider will ask you about your symptoms and examine you.
You may have blood tests, a urine test or imaging tests such as an ultrasound or CT scan. These are to rule out other causes of your symptoms.
Treating CHS
If you have severe vomiting, you may need short-term treatment such as:
- fluids into a vein (IV) to treat dehydration
- anti-sickness medicine
- pain medicine.
Many people find hot water helps with their symptoms, so they spend hours in the shower or bath.
The long-term treatment is to completely stop using cannabis. Just reducing your use will not cure the problem.
When you stop using cannabis, you will begin to feel better after a few days. But it can take weeks before all your symptoms go away. Your symptoms are likely to come back if you use cannabis again.
Getting help with CHS
As you have been able to use cannabis for years without problems, it can be hard to accept cannabis is the cause of your symptoms.
Completely stopping using cannabis can be difficult.
To get help, see your usual healthcare provider or access community support.
Written by HealthInfo clinical advisers. Page created May 2025.
SourcesReview key: HIADG-47857
