Cannabinoid hyperemesis syndrome (CHS) is a mouthful and it may sound like a frightening medical term, but it's really not so complex or intimidating. Think of it as a sort of cannabis allergy.
Instead of itchy eyes and runny nose, the most common symptoms are nausea and vomiting, according to Adie Wilson-Poe, Ph.D., a neuroscientist and an adviser to Weedmaps who has extensively studied how the compounds in cannabis interact with the endocannabinoid system.
“CHS is a condition where people experience continuous cycles of nausea and vomiting, brought on by cannabis consumption,” she explained.
Experts describe CHS as a “paradoxical condition,” because cannabis is known for its antiemetic properties — it's often used to help prevent vomiting and nausea. CHS is episodic, with vomiting episodes that typically last for 24 hours to 48 hours at a time separated by asymptomatic periods lasting weeks or months, according to a 2018 paper, “Cannabinoid Hyperemesis,” by NEMA Research Inc. in Naples, Florida.
“During episodes, patients suffer severe nausea and intractable vomiting often accompanied by abdominal pain for which conventional antiemetic therapy (such as ondansetron, promethazine, and metoclopramide) offers no relief,” the paper stated. “Protracted periods of vomiting (as often as 20 times a day) leaves some patients dehydrated, disoriented, and in electrolyte imbalance. Over time, unintentional weight loss may be reported.”
CHS is considered to be a rare condition and is most often reported by daily, long-term cannabis users. However, the prevalence of CHS is not certain. Many cases of CHS may be misdiagnosed or not medically treated, according to the NEMA paper.
The paper cites a study in Spain in which a questionnaire was sent to patients older than 18 who attended a single outpatient marijuana rehabilitation center in 2014. Twenty-two respondents, or 18.2 percent, reported symptoms suggestive of CHS. The paper cites another survey that shows incidences of CHS may be even higher.
“If these results are applied to the general population of regular marijuana users in the U.S., it is possible that 2.75 million Americans (range 2.13–3.38 million) suffer from CHS,” the paper stated. “It is likely many are not even aware that their symptoms relate to their cannabinoid use.”
Long-term or daily use, or high doses of cannabis, are believed to be the most likely causes. However, doctors and scientists don't yet know what causes some people to experience the cyclic vomiting most often associated with CHS while others go unaffected.
“There could also be some genetic or immune vulnerability in these individuals,” Wilson-Poe said. “What is very clear, however, is that it is specifically the cannabinoid molecules that trigger hyperemesis.”
It was once believed that toxicants, pesticides, or fertilizers used in cannabis production were the cause of CHS, but evidence has emerged over the last few years that the syndrome arises when the endogenous cannabinoid system is activated by cannabis, she said.
Cannabinoid Hyperemesis Syndrome Symptoms
The two clear indications that someone is suffering from CHS are: nausea and vomiting subside with either a hot shower, bath, or topical application of capsaicin; or the cessation of cannabis use.
“No other type of vomiting is reversed by heat,” Wilson-Poe said.
CHS is only one type of cyclic vomiting. If stopping cannabis use doesn't make the symptoms subside, another type of cyclic vomiting syndrome may be present. The duration and severity of these symptoms vary widely between people. The digestive tract contains numerous molecules that bind to THC, so it is affected by cannabis use. Therefore long-term cannabis use can change the way the affected molecules respond, and that can lead to CHS.
Using cannabis can alter the time it takes the stomach to empty, and it affects the esophageal sphincter, the muscle that opens and closes to let food from the esophagus into the stomach, according to an explanation from Cedars-Sinai Medical Center in Los Angeles.
According to Cedars-Sinai, CHS symptoms can be divided into three stages: the prodromal phase, the hyperemetic phase, and the recovery phase. Symptoms during the prodromal phase are usually early morning nausea and abdominal pain. Most people maintain normal eating patterns during this time, and some people use more cannabis because they think it will help stop nausea. This phase may last for months to years.
Symptoms during the hyperemetic phase may include ongoing nausea, repeated episodes of vomiting, abdominal pain, decreased food intake, weight loss, and dehydration. During this phase, vomiting is often overwhelming. This phase may continue until cannabis use is stopped. During the recovery phase, symptoms subside and appetite returns to normal. This phase can last days to months, while symptoms usually return if the person tries cannabis again, according to Cedars-Sinai.
How Can You Alleviate CHS Symptoms?
Treatment is performed acutely, meaning in the moment, as someone is experiencing symptoms, Wilson-Poe said. As previously mentioned, CHS can be treated by taking a hot shower, bath, or by applying capsaicin cream to the skin. However, those may be temporary fixes.
“Over the long term, the only treatment is to cease the use of cannabis,” Wilson-Poe said. “CHS may be a chronic, relapsing disease.”
By relapsing, it means that someone who has CHS may go through a period of abstinence, and still experience nausea or vomiting if they use cannabis at some point in the future. A 2017 paper, “Cannabinoid Hyperemesis Syndrome: Public Health Implications and a Novel Model Treatment Guideline,” shows antipsychotics like haloperidol and olanzapine have been reported to provide symptom relief.
“Conventional antiemetics including antihistamines, serotonin antagonists, dopamine antagonists and benzodiazepines may have limited effectiveness,” the paper states.
Another paper, “Cannabinoid Hyperemesis Syndrome: Diagnosis, Pathophysiology, and Treatment — a Systematic Review,” published in the Journal of Medical Toxicology in 2017, identified the major diagnostic characteristics in patients with CHS:
- History of regular cannabis use for more than a year (74.8 percent)
- At least weekly cannabis use (97.4 percent)
- Severe nausea and vomiting (100 percent)
- Abdominal pain (85.1 percent)
- Resolution of symptoms after stopping cannabis (96.8 percent)
- Men, as a percentage of reported symptoms (72.9 percent)