What Is Cyclic Vomiting Syndrome?
Cyclic Vomiting Syndrome, usually shortened to CVS, is a condition marked by recurring episodes of severe nausea and vomiting separated by periods of feeling completely normal. It’s been recognized in medical literature for well over a century, most commonly diagnosed in children, though it affects adults too and often gets missed or misdiagnosed for years.
How CVS episodes work
Episodes typically move through recognizable phases: a prodrome where you can sense an episode coming on, an intense vomiting phase that can last hours to days, a recovery phase, and then a symptom-free period that can stretch for weeks or months before the cycle repeats. Between episodes, most people with CVS feel entirely healthy — there’s no ongoing, day-to-day nausea the way there is with many other digestive conditions.
What triggers an episode
Triggers vary a lot by person, but common ones include emotional stress, certain foods, lack of sleep, infections, and for some people, a predictable link to their menstrual cycle. Family history of migraine shows up disproportionately often in people with CVS, and researchers think the two conditions may share some underlying biology.
How it’s diagnosed
There’s no single test for CVS. Diagnosis is based on a pattern — recurring, stereotyped episodes with symptom-free periods in between — after other possible causes have been ruled out through bloodwork, imaging, or endoscopy. This diagnosis-of-exclusion process is part of why it can take years for some people to get an accurate diagnosis.
Why CVS gets confused with CHS
Cyclical vomiting with clear episode phases is also the hallmark of Cannabinoid Hyperemesis Syndrome, a cannabis-specific condition that can look nearly identical on the surface — including the compulsive hot showers many patients in both groups report for temporary relief. The two conditions are different enough that mixing them up can lead to the wrong treatment plan, which is why we’ve put together a direct comparison of CVS and CHS.
FAQ
Is Cyclic Vomiting Syndrome the same as CHS?
No. CVS occurs independent of cannabis use and has its own distinct set of triggers, while CHS is specifically tied to chronic, heavy cannabis use and resolves with cessation.
Can adults develop CVS, or is it only a childhood condition?
Adults can absolutely have CVS. It’s more commonly diagnosed in children, but a significant number of adult cases exist, sometimes starting in childhood and continuing, and sometimes appearing for the first time in adulthood.
Written by the CHS SOS Team · Last updated: July 2026