While state lawmakers are rushing to legalize cannabis for various reasons, including so called “medical reasons,” and courts are moving toward approving none FDA approved cannabis for treatment of workers’ compensation pain management, the medical research is trailing these decisions.

A good metaphor for this approach is “fire, ready, aim” since little is known about the relative harms of edible and inhalable cannabis products. And not all of the emerging medical research is good news for cannabis users

A new study funded by the Colorado Department of Public Health and Environment., and published in the Annals of Internal Medicine, documented a sharp rise in emergency-room visits linked with marijuana following legalization in Colorado. One of the key drivers of the ER visits was a mysterious syndrome characterized by severe nausea and repeated vomiting.

The researchers were tasked to describe and compare adult emergency department (ED) visits related to edible and inhaled cannabis exposure. The study focused on a chart review of emergency room visits between 1 January 2012 and 31 December 2016 at a large urban academic hospital in Colorado.

They found 9973 visits with an ICD-9-CM or ICD-10-CM code for cannabis use. Of these, 2567 (25.7%) visits were at least partially attributable to cannabis, and 238 of those (9.3%) were related to edible cannabis.

Very little is known about the condition, called cannabinoid hyperemesis syndrome, or CHS. Cannabinoid hyperemesis syndrome can occur with cannabis use and is characterized by recurrent nausea, vomiting, and crampy abdominal pain.

The pathogenesis of cannabinoid hyperemesis syndrome is unclear, but it may involve accumulation of exogenous cannabinoids or alterations in the brain’s regulation of body temperature.

The prodromal phase is characterized by subsyndromal symptoms of cannabinoid hyperemesis syndrome, including mild discomfort and nausea upon waking. Prior to the use of compensatory exposure to hot water to treat symptoms, people sometimes increase their intake of cannabinoids in an effort to treat the persistent nausea they experience. This phase can last for months or even years

The hyperemetic phase is characterized by the full syndromal symptoms of cannabinoid hyperemesis syndrome, including persistent nausea, vomiting, abdominal pain, and retching. Retching can occur up to 5 times per hour. It is very difficult to take food or medicine by mouth during this stage, and patients may develop a fear of eating. Weight loss and dehydration due to decreased oral intake and vomiting are possible.

Compensatory exposure to hot water, even for hours at a time, may be attempted for symptomatic relief, resulting in compulsive bathing/showering. People have described the hot water relief as “temperature-dependent,” meaning that hotter temperatures provide greater relief. It is during this phase that people with cannabinoid hyperemesis syndrome are likely to present to the emergency department of the hospital for treatment.

Individual attacks can lead to complications, such as acute kidney injury. In the setting of cannabinoid hyperemesis syndrome, this may be defined as cannabinoid hyperemesis acute renal failure (CHARF).

CHARF occurs through dehydration secondary due to persistent vomiting and hot showers, leading to prerenal azotemia. A case report of acute renal failure, albeit in the setting of rhabdomyolysis, has been reported with the use of synthetic cannabinoids.

While definitive treatment involves abstinence from cannabinoids, various drug therapies have been studied for symptomatic relief in the acute presentation of a patient suffering from cannabinoid hyperemesis syndrome, often in the setting of a hospital emergency department.