Emergency departments are seeing more people with bouts of severe nausea and vomiting linked to long-term cannabis use.
The condition now has a name and a formal diagnostic code: cannabis hyperemesis syndrome.
It is still poorly understood and often missed, which means people can bounce in and out of A&E for years before anyone joins the dots.
What is cannabis hyperemesis syndrome
Cannabis hyperemesis syndrome is a gut condition seen in regular cannabis users.
It typically involves:
- Sudden episodes of intense or prolonged vomiting
- Abdominal pain
- Symptoms that start within 24 hours of the last cannabis use and can last for several days
- Attacks that recur several times a year
One odd but common feature is that people often feel better in a hot shower or bath.
Some report spending hours under hot water during an episode.
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New diagnosis code and why it matters
On 1 October, the World Health Organization added cannabis hyperemesis syndrome to its International Classification of Diseases (ICD-10).
The US has adopted the code R11.16, and other countries are likely to follow.
Having a specific code allows:
- Clear documentation in medical records
- Easier recognition of repeated episodes
- Better data on how common the condition is
- More reliable research into causes and treatments
Researchers like Dr Beatriz Carlini point out that until now, cases were hidden within vague labels like “vomiting” or “abdominal pain”, which made tracking trends very difficult.
Why many people and clinicians miss it
There are several reasons this syndrome flies under the radar:
- Cannabis is widely known for easing nausea in cancer and other long-term conditions, so patients and clinicians may not see it as the culprit
- Some people have used cannabis for years without obvious issues and struggle to accept that it could suddenly be a problem
- Awareness among clinicians is still patchy, as the condition has only recently been formally recognised
As a result, people often attend A&E multiple times, have numerous tests and rack up big medical bills in some countries before anyone considers cannabis hyperemesis.
What might be causing it
No one knows for sure why some cannabis users develop this syndrome and others do not.
Possibilities include:
- Higher strength products with more THC
- Greater overall use and more frequent dosing
- Individual differences in how the body’s endocannabinoid system responds
There does not seem to be a “safe” dose for those who are vulnerable. Some people start vomiting even with relatively small amounts of cannabis.
Treatment and what seems to help
Stopping cannabis use is currently the main way to prevent further episodes.
However, that is easier said than done, especially if someone is dependent or believes cannabis is helping another condition.
During an acute flare:
- Standard anti-sickness tablets often do not work well
- Some doctors use medicines like haloperidol, normally used in mental health, to control symptoms
- Some patients get partial relief from capsaicin cream, applied to the abdomen
- Very hot showers or baths are commonly reported as providing temporary relief
Because the condition comes and goes, some people stop cannabis briefly, feel better, then start again and end up in the same cycle.
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What this means for people with diabetes
For people with diabetes, repeated bouts of vomiting can quickly knock blood sugars off balance and increase the risk of dehydration and diabetic ketoacidosis, particularly in those using insulin.
Anyone with diabetes who uses cannabis and keeps having unexplained vomiting episodes should mention this to their GP or diabetes team, rather than assuming it is a stomach bug every time.
Study context: based on work from University of Washington and colleagues following the introduction of an ICD code for cannabis hyperemesis syndrome.
