Miriam was vomiting uncontrollably on a summer morning in 2022 when she arrived at a Utah hospital. She was diagnosed with a condition she had never heard of.
This was her third ER trip with cannabinoid hyperemesis syndrome (CHS) in as many years. The first time she vomited for 12 hours, the second for 36 hours. This time, the worst and last, the intense pain lasted five days, during which, she was later told, she had hallucinatory conversations and threatened to leap from a fourth story window.
Miriam, 45, who asked for professional reasons to use only her first name, had a legal marijuana prescription to treat both PTSD, acquired from years of driving an ambulance, and chronic pain from an auto accident.
This was all true, but the real reason she needed cannabis that summer was that her mother was dying of a rare blood infection, and she had just been diagnosed with thyroid cancer.
She needed emotional help. And help was at hand.
Having used marijuana off and on since high school, Miriam had a high tolerance for THC, the drug’s main psychotropic compound. But after a single drag on a 95 percent pure THC vape pen purchased at a local medical dispensary, it felt like her body was in a vice.
“Every nerve was going off,” Miriam told me. “I hurt physically everywhere. If I had to choose between doing that again and being eaten by a bear, I would choose the bear.”
The race to legalize marijuana
CHS is rare but becoming less so. The key risk factors are long-term, frequent and heavy marijuana use. Symptoms begin with nausea, followed in later episodes, often separated by a year or more, by cyclical vomiting, dehydration, and emergency room visits.
The New York Times estimated last year that 6 million Americans may have CHS symptoms from using marijuana. The syndrome’s rates have risen as more Americans consume higher-potency cannabis with greater frequency. Over recent decades breeding has dramatically increased THC content in the plant itself, while purified THC products are now ubiquitous.
At the federal level, marijuana remains a Schedule 1 illegal drug, alongside heroin, LSD and a few others. But at the state level, the race to legalization in recent years has been dizzying. Several states and territories have significantly liberalized marijuana access. According to the National Conference of State Legislatures, as of January, 39 states allow medical marijuana, with 24 of those having fully legalized weed.
And yet, amid this enthusiasm, prominent health researchers are sounding alarms. And CHS is just one of several emerging concerns. While few experts now advocate a full return to prohibition, many do worry that the accelerating pace of easy access and heightened potency are outstripping scientific evidence on the safety of long-term marijuana use — and, when used as medicine, its efficacy.
In particular, many experts point to the long-term effects on the developing minds and bodies of adolescents and young adults, calling out overlooked risks of regular marijuana use to developing brains and bodies in their 20s.
“We allowed people to vote whether or not cannabis is a medicine,” noted Yasmin Hurd, a neurobiologist at the Mount Sinai Medical Center in New York City. “Now we’re asking everybody in the country to be their own doctor with cannabis.
“That has never been done with any other medicine.”
Recent polls show that 88 percent of Americans favor legal medical use of cannabis, and 60 percent full legalization.
What science says
In 2023, the National Survey on Drug Use and Health found that nearly 44 million Americans used marijuana in the past month. By comparison, the same report cites 135 million daily alcohol users. “Far more people drink,” noted one study, “but high-frequency drinking is less common. In 2022, the median drinker reported drinking on 4–5 days in the past month, versus 15–16 days in the past month for cannabis.”
Among those daily or nearly-daily users are many who look to cannabis for help with assorted ailments. In 2018, the International Cannabis Policy Study found that 27 percent of North Americans between 16 and 65 had used cannabis to help with pain, sleep, migraines, anxiety, depression and PTSD. Conditions that qualify under Utah’s medical cannabis law include HIV, Alzheimer’s, ALS, cancer, Crohn’s disease, epilepsy, multiple sclerosis and PTSD.
Whether all these medical hopes could withstand random controlled trials is the key unanswered question. For now, the evidence is mostly weak or nonexistent. On treating PTSD with cannabis, for example, the American Psychiatric Association actually issued a formal statement opposing the use of cannabis to treat PTSD, emphasizing that “no published evidence of sufficient quality exists in the medical literature to support the practice.”
In 2017, the National Academies of Sciences, Engineering, and Medicine released an exhaustive report on cannabis science and policy that remains the most widely-cited reference. For medical uses, the National Academies study found “insufficient or no evidence.” But it did support improvements in three areas: “chronic pain,” “chemotherapy-induced nausea and vomiting,” and “spasticity associated with multiple sclerosis.”
But even the study’s chronic pain section concludes that “very little is known about the efficacy, dose, routes of administration, or side effects” and warns that the products being sold to consumers and patients bear “little resemblance to the products that are available for research.”
‘I’d never had access to anything that strong’
Utah’s dispensaries are home to a huge variety of THC materials. In addition to raw cannabis flower, there are vapes, liquids, concentrates, tinctures, topicals and edibles. Gummies are available in a multitude of fruit flavors. And vape cartridges come with names like “galactic gas,” “piña gluelada,” “mountain diesel” and “pappy poison.”
Utah medical cannabis law allows up to 113 grams of raw cannabis flower a month. Depending on the potency, that could be enough for seven joints a day. On top of that, the law allows 20 grams of purified THC in other forms like edibles, tinctures and vapes. That’s enough for 66 potent gummies every day. No one really could handle that much. In short, under Utah law there is nothing stopping a willing doctor from giving eager patients all the THC their body could handle and more.
Just contemplating the plethora of delivery devices and variety of formulas and potencies on the dispensary sales floor is nearly as mind-blowing as consuming them. “I’ve been smoking pot since I was 14,” Miriam said, “but I’d never had access to anything that strong.” It was there, in her local Utah dispensary, that Miriam purchased the 95 percent pure THC vape pen that sparked her final cannabinoid hyperemesis syndrome incident.
“We allowed people to vote whether or not cannabis is a medicine. Now we’re asking everybody in the country to be their own doctor with cannabis. That has never been done with any other medicine.”
Exactly how THC affects the body is still a mystery. Not until 1988 did researchers begin to map the delicate system we now call the endocannabinoid system, a network of receptors and internal cannabinoids that are active throughout the body.
The network relies on subtle nudges to modulate stress, appetite, hormones, memory, emotions, sleep, body temperature, pain and the immune system. That sweeping portfolio may in time uncover previously unimaginable treatments for difficult conditions, says UC Irvine’s Daniele Piomelli, who since the early 1990s has been a key player in endocannabinoid system research.
Piomelli is a neuroscientist who argues that the brain cannot be considered separately from the body. “The endocannabinoid system works in all these tissues and all these organs,” Piomelli said. And the daily use of THC in adolescence will permanently affect how the ECS works in organs that regulate health.
A flood of THC appears to slow internal cannabinoid production and attenuate receptor networks, Piomelli said. More THC is then required for a similar effect, a key marker of addiction. Those system disruptions can also lead to severe inflammation and immune and digestive problems, such as Miriam experienced with CHS.
A 2022 study in Colorado linked cannabis to increased temporary psychosis. A recent article on the Yale School of Medicine website noted that “heavy and early use of cannabis is associated with increased risk of developing schizophrenia, bipolar disorder, depression, and anxiety.”
Neurobiologist Yasmin Hurd has done pathbreaking work on the neurological risks of adolescent THC use, but she also studies the therapeutic potential of cannabidiol for opioid addiction.
Now a professor at the Mt. Sinai Medical Center’s Icahn School of Medicine, Hurd has been working since the early 1990s with rats, first studying cocaine, amphetamine and heroin addictions. When she turned to cannabis 20 years ago, her colleagues laughed. “Oh, that’s not a drug, you know,” they said. At the time, most people were still convinced cannabis was not truly biologically addictive.
But she found that rats given THC as adolescents would self-administer heroin at higher rates once they were adults. At least for rats, it was now clear that the cannabis gateway to opiates is biological.
“People aren’t laughing at me that much anymore,” she said.
Hurd also found that brain scans of adult rats exposed to THC as adolescents showed attenuated neural networks. Those scans, she says, look very similar to human schizophrenia. Subsequent human studies, Hurd says, have confirmed that “adolescent exposure to cannabis does indeed change the prefrontal cortical in a manner similar to what we had shown in animals.”
Hurd also notes a Danish epidemiological study that showed a strong correlation between increased cannabis use and potency and rising schizophrenia rates. That study found much lower schizophrenia rates among those who began cannabis use after they turned 26, suggesting a link to prefrontal cortex maturation. Most experts now see the evidence linking adolescent cannabis use to heightened schizophrenia as compelling.
Hurd makes a point of clarifying “adolescence.” Neurologically, human adolescence does not end until age 25, when the prefrontal cortex matures. Women mature a bit earlier and men a bit later. At 21, legal young adults are still neurological adolescents, and will be for years.
In a finding Hurd fairly describes as scary, her lab also discovered that rats given THC as adolescents can pass epigenetic damage to the second and third generation. Descendants struggled to manage stress and were more prone to self-administer heroin.
But Hurd is not only framing problems; she is also looking for solutions. She began studying cannabidiol (CBD) long before it became popular. Like THC, cannabidiol is an important compound in the cannabis plant, but it has very different effects. The balance of CBD and THC is often considered critical in therapeutic uses.
“We found that CBD actually did the opposite to THC,” she said. “Animals exposed to CBD reduced their heroin seeking.” Hurd is now a co-principal investigator in advanced clinical trials, with results so far confirming that CBD can be used to effectively reduce opiate craving.
When she began researching THC’s impact on adolescent brains, Hurd says the cannabis industry marked her as an enemy. Once she began researching cannabidiol therapies, the industry decided she might be OK. But she has never cared about what they think. “Follow the data,” she tells her research team. “No matter what the results are, the data tells us.”
“People should not be using it when they’re young and their brains are still developing.”
Following data is easier said than done. Everybody is using different kinds of medical cannabis for dozens of different conditions, said Ryan Vandrey, a psychiatry professor at the Johns Hopkins medical school, “but they’re all doing it different, making it very hard to integrate the data.”
Databases demand consistent inputs. To make that possible, Vandrey and his colleagues at Johns Hopkins recently got a $10 million grant for a five-year project to create a standardized assessment and collect large quantities of observational data that will, they hope, be followed by good clinical trials.
“If you were to ask me which health conditions should be studied with a large clinical trial,” Vandrey told me, “and what the product would be, I couldn’t tell you.”
‘It was not an easy decision’
The stories Vandrey needs are in the files of general practitioners like Dr. Matt McIff. About 100 of McIff’s patients currently use medical cannabis, mostly for chronic pain. However, he opposes recreational legalization — or even casual medical legalization where the difference gets blurred.
McIff illustrates his approach with two cases from his practice. Fittingly, they serve as bookends to Yasmin Hurd’s dual research tracks: CBD for opioid addiction and adolescent THC risks.
The first case is a carpenter with chronic pain from a work injury who disclosed that he had for years struggled with opiate painkiller addiction but was now sober, implying that he white-knuckled his recovery — a rare and difficult feat.
With his curiosity piqued, McIff asked directly if the patient had used cannabis to overcome opiate cravings. Of course, he had. “After I assured him it was OK,” McIff said, “his eyes got really big and he teared up. He was so relieved to have his experience legitimized.”
The patient still uses a moderate cannabis dose for sleep and pain, a careful balance of THC and cannabidiol. But he is opiate-free, married with two children, and runs a business with 10 employees.
On the flip side, McIff tells of a 17-year-old patient who had self-medicated for his anxiety with cannabis obtained from friends. McIff walked the mother and son through the risks of adolescent cannabis — CHS, addiction risks, cognitive dysfunction and harms to the developing brain and body.
Finally, he suggested that teens who use cannabis for anxiety may shortchange their emotional development. The stress and confusion in youth, he said, is sometimes just part of learning life skills under pressure. Early cannabis use that masks stress may not only damage neural networks but also undercut psychological growth.
“If you are 17 and feeling stressed and you haven’t developed emotional skills,” McIff told me, “cannabis becomes a substitute.”
McIff is an outspoken advocate of supervised medical cannabis, but also an outspoken opponent of recreational legalization. In his view, the very respect he has for the drug’s potency pushes back against its unsupervised casual use for entertainment or self-medication.
McIff’s reticence on legalization makes him a bit of an outlier. Despite layer upon layer of health concerns, none of the other experts I spoke with favored continued prohibition.
For example, Christopher Andrews, a gastroenterologist in Calgary, Canada, and an expert on cannabinoid hyperemesis syndrome, was philosophical when I asked about Canada’s permissive 18- to 21-year-old limit for recreational cannabis, given the developmental realities of the human body noted above.
“People should not be using it when they’re young and their brains are still developing,” Andrews said. But he was sympathetic to Canadian policymakers, who feared the black-market realities of trying to enforce prohibition until a later age.
“It was not an easy decision,” Andrews said. “That’s for sure.”
Rather than going back to a policy of blanket prohibition, most researchers I spoke with, like Andrews, are focused on doing the long-delayed science required to better quantify both the perils and promise of cannabis.
“Follow the data. No matter what the results are, the data tells us.”
Not all doctors who prescribe cannabis are as careful as McIff. Miriam, for example, got her prescription from a doctor she had never previously met, located in a cannabis medical clinic in the same building as the dispensary. “You sit down at a desk with the doctor. They ask you a few questions, and then they write you a prescription and you walk out the door,” Miriam said.
No one probed her underlying needs, checked on current therapies, explored alternatives — or even taught her how to balance THC and cannabidiol. Miriam finds it alarming that neither the doctor nor the dispensary staff warned her of CHS — a foreseeable risk, however rare, that she would have recognized in her own profile if it had been described.
Now with 18 months of recovery behind her, Miriam makes a surprising admission. She’s glad she was forced to quit. Cold turkey recovery, she says, made her realize she had been using not just for pain and PTSD, and not just to grieve her current loss, but also to bury unresolved emotional issues from her youth. “I used pot to avoid dealing with my stuff,” she said. “It was convenient that it was legal.”
After her crisis, Miriam spent three months at home on bed rest. With little else to do, she joined remote group therapy sessions twice a day. At first her engagement was perfunctory, even petulant. Uncovering old hurts and grieving new losses without her chemical crutch was wrenching. But the payoff was worth it.
“Having to grieve my mom and grieve having cancer 100 percent sober was the best thing that ever happened to me,” she said. “I have less pain than I’ve ever had in my life. I have less anxiety. And I’m so glad that I can’t smoke pot.”
This story appears in the March 2025 issue of Deseret Magazine. Learn more about how to subscribe.
Amid the enthusiasm to legalize marijuana at the state level, prominent health researchers are sounding alarms. Read More
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