"There is a large body of literature describing the diagnosis, pathophysiology, and treatment of CHS [Cannabinoid Hyperemesis Syndrome]. However, most of the evidence is considered low quality because it is in the form of case reports and case series. When these reports are combined, a larger and more robust set of diagnostic characteristics, evaluation of pathophysiology, and determination of effective treatments can be generated. Based on our knowledge of 211 unique CHS patients, the following characteristics are associated with the syndrome: (1) severe cyclic vomiting that is usually accompanied with abdominal pain, (2) symptom onset preceded by at least weekly cannabis use, (3) temporary relief of symptoms with compulsive hot baths/showers, (4) resolution of symptoms with cessation of cannabis use, (5) onset of cannabis use in the teenage years, and (6) symptom onset in the third decade of life. While not all these criteria must be met to make the diagnosis, of 133 cases for which raw data were available, 85 met at least four criteria (75.2%) and 104 (92%) met at least three criteria. Secondary to incomplete and inconsistent reporting of the proposed diagnostic characteristics in the case report literature, the aforementioned data may be an underestimate of the actual occurrence of these symptoms in CHS patients.
"CHS shares many clinical similarities with cyclic vomiting syndrome (CVS), a functional gastrointestinal disorder. A diagnostic dilemma arises when CVS patients concurrently use cannabis, as it can be difficult to discern if the true underlying disorder is CHS or CVS that is being symptomatically managed with cannabis."
Sorensen, C. J., DeSanto, K., Borgelt, L., Phillips, K. T., & Monte, A. A. (2017). Cannabinoid Hyperemesis Syndrome: Diagnosis, Pathophysiology, and Treatment-a Systematic Review. Journal of medical toxicology : official journal of the American College of Medical Toxicology, 13(1), 71–87. doi.org/10.1007/s13181-016-0595-z.