Genetic risk factors?
One mystery is why some regular marijuana users get this syndrome while others do not.
“I can say that not everybody gets this, thank goodness,” said Ethan Russo, MD. “But there has to be a reason that certain people are susceptible and others are not.”
Interestingly, a new study from Dr. Russo and colleagues suggests that genes play a role. They identified five genetic changes that could make a chronic marijuana user more likely to have cannabinoid hyperemesis syndrome in a study published July 5, 2021, in the journal Cannabis and Cannabinoid Research.
They compared 28 people with the disorder with 12 other high-frequency marijuana users without these symptoms.
The results are not final but could help guide future research, Dr. Russo said.
“What we’ve discovered – and it was far more than we expected – is that there’s a lot more to this than a hypersensitivity to cannabis,” said Dr. Russo, a neurologist and founder/CEO of CReDO Science, a firm that promotes cannabis research and develops commercial products.
Also, he said, those affected by cannabinoid hyperemesis syndrome could be at higher risk for other conditions, such as addiction to alcohol or other substances, dementia, diabetes, and heart disease.
“Most people with [cannabinoid hyperemesis syndrome] are going to be younger,” he said. “What we’ve demonstrated is there is a risk for more serious problems for decades to come. So someone who has these symptoms really deserves a look at this genetic screening.”
Battling disbelief
Getting back to the paradox, many users don’t believe marijuana can trigger serious vomiting and nausea because of its reputation for doing the opposite.
“Folks that have this are just uniquely resistant to the concept that cannabis is actually the problem and not the solution,” Dr. Russo said.
“It’s kind of counterintuitive because people think: ‘Oh, cannabis helps with nausea,’ so they use more of it,” said Dr. Vinocur, who is also a spokesperson for the American College of Emergency Physicians and runs a medical cannabis practice.
Most kinds of marijuana act in this way – doing opposite things at different doses. Once a certain threshold is passed, people with cannabinoid hyperemesis syndrome are “just uniquely susceptible and really can’t tolerate any significant amount of THC,” Dr. Russo said, referring to tetrahydrocannabinol, the substance that gets marijuana users high.
Once diagnosed, quitting is the most effective strategy. But it can be tough to persuade someone to stop using marijuana.
“You do have to try and convince them ... to try abstinence and to watch and see what happens,” Dr. Vinocur said.
People should “realize the root cause of this is its cannabinoid ingestion, and the treatment is really best directed at absolute avoidance,” Dr. Johnson said.
Unfortunately, evidence also shows that once a person stops using marijuana and gets relief, going back to marijuana or other forms of cannabinoids can cause the syndrome to start all over again.
“We’ve had people that quit for a month, a year, 2 years and upon resumption, almost invariably, they’re back into bouts of the hyperemesis along with all the other [symptoms],” Dr. Russo said.
Marijuana and cannabinoids can cause digestive problems, Dr. Johnson said, which may cause more problems.