Weed sick: High-potency cannabis leads to ER visits, illnesses for some users

D

on Danielson of Sedro Woolley is the kind of person who would rather point to the evidence than state his opinion.

When he wants to explain how popular his 27-year-old son Brandon was when he died, he describes the turnout at his son’s funeral in 2019. Hundreds of people packed the church. It was standing room only — old people, young people, people from other countries who Brandon had met.

“He was very outgoing. He had tons of friends,” Don Danielson said. “He married his high school sweetheart. They were literally months away from going on their honeymoon that they waited for when he passed. They were looking to buy their first house.”

According to his death certificate, Brandon Danielson died of cannabinoid hyperemesis syndrome, or CHS, a condition that results from daily use of cannabis, especially high-THC concentrates. As cannabis products like vapes, shatter, and dabs have reached near 100% potency, doctors across Washington state are seeing an increase in cannabis-related disorders, including CHS.

Like many people who develop CHS, Brandon Danielson was initially misdiagnosed. Doctors thought he had cyclical vomiting syndrome, a condition with similar symptoms — extreme abdominal pain, severe bouts of vomiting, and nausea.

“It was so new, we didn’t even know what CHS was,” his father said. “He smoked a lot of weed, but it was the concentrates. It’s the concentrates.”

In September, Brandon Danielson was getting ready to go to work, when he had a seizure. He was so severely dehydrated from vomiting that his organs shut down.

“His wife, my daughter-in-law, found him after she got home from work,” his father explained. “It’s the worst pain you could ever feel, losing a child. He was an adult, but he was still my child.”

The cannabis Brandon Danielson consumed was much stronger than anything that was available prior to the 2010s, when a growing number of states began to legalize recreational use.

Of the people who reported vaping cannabis in the 2023 International Cannabis Policy Study, the average oil they vaped was 71.6% THC. That’s almost 20 times stronger than the potency of weed that was for sale illegally in the U.S. in 1995, which had an average THC content of 4%, said Denise Walker, a research professor at the University of Washington School of Social Work in Seattle.

“THC potency has increased over the years astronomically,” Walker said. “We can get much more potent strains, now that we have legalized retail cannabis and instituted no limits on THC concentration. It can go up to 99% THC.”

While pot potency has gone through the roof, so have cannabis use and recreational sales, which topped $1.2 billion in Washington state in 2024. Marijuana has now surpassed alcohol as the daily drug of choice based on usage, and the state has reaped the benefits in the form of hundreds of millions of dollars in taxes from recreational marijuana sales every year.

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For years, lawmakers, researchers, and doctors have sounded the alarm about a potential public health crisis — cannabis-induced psychosis is on the rise, cannabis use disorder is increasing among teens and young adults, and a growing body of research shows a connection between daily cannabis use and schizophrenia.

But those advocates are fighting a multibillion-dollar cannabis industry resistant to any form of regulation and a public largely convinced marijuana is harmless.

What most people don’t realize, researchers say, is that the THC young people are vaping and dabbing today has little resemblance to the marijuana of decades past.

‘Strawberry frosted Pop-Tarts’

Bia Carlini, a research associate professor at the Addictions, Drug & Alcohol Institute at the University of Washington School of Medicine, has a saying that might best describe the relationship between the marijuana most people are familiar with (and what many voted to legalize in 2012) and high-potency cannabis concentrates sold at retail stores across the state.

She said it’s like comparing strawberries to strawberry frosted Pop-Tarts.

“The plant is so processed, it is enhanced by so many manufacturing processes, extractions, additions, concentrations,” Carlini said. “Then you add external flavors. You suck the THC out of the plant and make a gooey material. It becomes detached from the plant.”

Carlini chaired a working group in 2020 that documented the health effects of high-potency cannabis products, such as cannabis vape pens, shatter (a form of marijuana wax that resembles glass derived from butane hash oil), and dabs (a gooey substance made by extracting THC using a solvent like butane or CO2).

The central question posed by state lawmakers and health officials to Carlini’s research team: “Is high-potency cannabis use safe for the citizens of Washington state?”

The answer to that question depends on who you are and how much you use.

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Carlini’s team concluded that high-potency cannabis “can have lifelong mental health consequences, which often manifest in adolescence or early adult use.” The group’s report said using high-potency products daily increases the risk of developing psychotic disorders such as schizophrenia, and is connected to an earlier onset of psychotic symptoms.

The report concludes that “THC content of cannabis products contributes to adverse health effects in a dose-response manner.” In other words, the higher the potency, the more likely users are to get sick from or addicted to weed.

That conclusion came as no surprise to Dr. Ethan Russo, a neurologist based on Vashon Island who has been studying the medicinal value of cannabinoids and developing cannabis-based medicine for close to 30 years. Russo has been running his own company, CReDO Science, since 2020, “devoted to making cannabis safer and better.”

But even Russo, whose professional life revolves around the benefits of cannabis, has been calling out the dangers of high-potency concentrates — a danger he said is universally applicable to any drug.

“From the time of the Greeks it has been noted: The difference between a medicine and a poison is the dose,” Russo said. “Everything has side effects if you use too much. That’s certainly the case with cannabis. In low doses, it is a fabulously therapeutic compound. In high doses, it renders one anxious, paranoid, even delusional. So, the point is not to use too much.”

But measuring dose is a challenging task for people smoking and vaping cannabis, and for researchers trying to gauge the effects of daily use.

“Edibles are probably the easiest, because at least you can get milligrams, and that’s a finite amount,” explained the UW’s Walker, who has been researching cannabis and cannabis interventions and treatments for more than 20 years. “But if you say, ‘Oh, well, I smoke a few hits off my bong four times a day,’ I just know frequency and maybe the maximum potency in that product, but I don’t know really what you’re intaking, versus if you said, ‘Well, I drink three beers a day.’ We know exactly how much you’ve ingested, and we can calculate your BAC [blood-alcohol content]. We don’t have the same equivalent for cannabis.”

Industry v. regulation

Any effort to regulate Washington’s cannabis has faced stiff resistance from industry lobbyists in Olympia, including tactics that lawmakers and researchers compare to those used by big tobacco and big pharma.

State Rep. Lauren Davis (D-Shoreline) has faced the brunt of that resistance for the past five years. Davis has a background in behavioral health, mostly focused on suicide prevention and the opioid epidemic.

During her first term as a lawmaker, she asked staff for a memo about cannabis regulation. The response said the state had a potency cap of 10% THC on edibles and 30% potency on flower (or bud). But when it came to concentrates, there was no cap.

“That single sentence sort of jumped off the page,” Davis said. “Like, wait, what?”

The memo also said sales of high-potency products more than doubled in four years, from less than 14% of the market in 2015 to 37% in 2019.

The Washington State Liquor and Cannabis Board was unable to provide an exact percentage of the state market for high-potency sales in 2024. Communications Director Brian Smith said via email that the “processing sector” now accounts for more than half of all retail sales, although that can include products that contain less than 35% THC.

Smith also said vapes and concentrates make up 38% of sales, and they tend to appeal to younger users, who are more at risk for developing cannabis use disorder and experiencing cannabis-induced psychosis, which research shows increases the chance of people developing schizophrenia.

“Gen Z people are purchasing more vape pens than any other generation, which is concerning given those are the people at highest risk,” he said.

As the amount of people using high-THC concentrates climbs, so too does the number of young people getting sick, not just in Washington state but nationwide.

Dr. Alexis Ball at Seattle Children’s was the lead author of a study that looked at more than 106,000 substance-related emergency room visits by young people between the ages of 12 and 21 at pediatric hospitals across the U.S. between 2016 and 2021. Cannabis not only accounted for the majority of visits during that five-year span (at 52%), but cannabis-related visits also increased the most during the study, jumping by more than 80%.

Cannabis and psychosis

Meanwhile, an increasing number of studies have linked high-potency THC to psychosis. A Danish study found that 20% of schizophrenia cases might be prevented if young men (ages 16 to 25) did not develop cannabis use disorder, or CUD. The likelihood of developing CUD is significantly higher when people use high-potency concentrates, according to that 2023 study.

People who experience cannabis-induced psychosis — hallucinating or suffering delusions after ingesting cannabis — are more likely to develop schizophrenia in the years that follow.

A 2023 study found that one-quarter of people who go to emergency rooms for cannabis-induced psychosis develop schizophrenia within three years. A Finnish study of more than 18,000 people found that close to half of people who suffer cannabis-induced psychosis are diagnosed with schizophrenia within eight years.

More recent studies also suggest that the risk of psychosis is not connected to genetic predispositions, a claim often made by cannabis industry lobbyists. In other words, using high-potency THC can lead to schizophrenia even if users don’t have relatives who suffer from the disease. New research also shows a connection between CUD and other mental health issues, such as bipolar disorder and depression.

Based on her background in behavioral health, Rep. Davis knew the challenges that people with schizophrenia and their families face. Schizophrenia is incurable, so preventing its onset is key.

“If somebody told me as a lawmaker that I could prevent a third of cases of schizophrenia in my state, why would I not be keenly interested in that policy lever?” she asked.

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Every year in office, Davis has put forward bills to regulate recreational cannabis: proposing a cap on THC potency at 35%; calling on lawmakers to increase the minimum purchase age to 25 (when human brain development is complete); sponsoring legislation to tax high-potency products; and adding warning labels directly on products with THC percentage of 35% or more. Those bills have all failed to pass the Legislature.

On her fifth attempt, in 2024, Davis managed to get a watered-down version of her bill passed. The new law requires dispensaries as of Jan. 1, 2025, to display “a conspicuous notice at the point of sale” about potential health risks, especially for people under the age of 25, of consuming cannabis.

Those displays say that, “Frequently using products with 35% THC or higher can increase the risk of developing mental health disorders,” and they note that the risk is higher if people have psychosis in their families and if they are under the age of 25.

The new law also provides money to study the dangers of high-potency THC products and to pay for messages and media campaigns to educate the public about cannabis dangers.

A strategy of distraction

The Addictions, Drug & Alcohol Institute at the UW School of Medicine is widely recognized as the premier source of cannabis research in the state. Since its founding in 1973, the institute has awarded more than $3.5 million to researchers in 40 UW departments, funding about 350 projects.

The institute includes the Cannabis Education & Research Program, headed by Carlini, which has been partially funded by the Washington State Dedicated Cannabis Fund since 2015.

Over the last decade, Carlini and her colleagues have compiled extensive research on the increasing dangers of high-potency cannabis products,and delivered reports to state lawmakers, often funded by the state. In 2024, Carlini directed the first symposium in the U.S. focused on the connection between cannabis use and psychotic disorders.

Two years earlier, an Addictions, Drug & Alcohol Institute report commissioned by the Washington State Health Care Agency pointed to the dangers of high-THC products and recommended many of the policy changes being pushed by Davis.

Carlini tracked the cannabis industry resistance to Davis’ bills and published a paper in 2024 that broke down the industry strategy — a strategy that followed similar tactics used by the alcohol industry, big tobacco, and promoters of high-sugar beverages. At the heart of the strategy were three tenets: threaten, distract, and discredit.

“The most frequently used rhetorical strategy was [claiming regulation would present] threats to economic benefits, public health, and the will of the people,” concludes the paper, published in the May 2024 issue of the Journal of Studies on Alcohol and Drugs. “The other two most apparent strategies were distracting from the bill’s focus by introducing a tangential topic and discrediting the science that supported regulation of cannabis products with high THC concentration or its advocates.”

The paper analyzed the public testimony of 33 cannabis industry supporters who spoke before the House Commerce & Gaming Committee over the course of four years against measures to regulate high-THC cannabis. Carlini and her colleagues found that industry advocates repeatedly questioned the validity of research that raised public health concerns, and denounced public health officials and other proponents of increased regulations as biased and untrustworthy.

In response to KUOW’s questions about the dangers of high-THC products, a spokesperson from the Washington CannaBusiness Association blamed the “illicit marketplace” — such as online sources and gas stations — for providing underage users with cannabis products not subject to “rigorous safety standards for production and processing of cannabis.”

“Illegal production of these products in garages and elsewhere continues to be a significant safety concern,” the association said.

The association did not comment on public health concerns related to high-THC products sold legally in Washington state, which are at the heart of regulation efforts.

Cannabis and schizophrenia

One of the cannabis industry’s central arguments, which new research is disproving, is that daily cannabis use only leads to schizophrenia when users have a history of schizophrenia in their family.

This was not the case for Gayle, a Seattle area woman whose son developed psychosis after using cannabis extensively in his youth, long before cannabis products had the potency they have now. Gayle agreed to speak with KUOW on the condition of not publishing her last name.

Her son began exhibiting psychotic behavior in his 20s. He was repeatedly admitted to various psychiatric hospitals and sentenced to jail multiple times. He had at least four periods of homelessness, and lived in shelters for months at a time, Gayle said.

In the fall of 2020, he was admitted to a psych unit. He is now a ward of the state and living in an adult family home where he receives supervision 24 hours a day.

“I think people need to know that real people have gotten schizophrenia who did not have other risk factors. They didn’t come from poverty. They didn’t come from a long line of people with schizophrenia,” Gayle said. “It’s much better to learn vicariously through someone like me than to have it happen in your own family.”

Growing awareness

While a growing body of research is making the connection between cannabis and schizophrenia more clear, health professionals are seeing an increasing awareness of other cannabis-related illnesses, such as the cannabinoid hyperemesis syndrome (CHS) that led to Brandon Danielson’s death.

Kelly Kerby, a mental health counselor and substance use disorder professional, has worked at Seattle Children’s for two stints — first from 2009 to 2015, and more recently in her current role since September 2020.

During her initial six years at Children’s, almost no one knew about CHS. When she suspected a teenager had the syndrome, he was dubious.

“Hardly anyone had heard about it, and he would not believe me that he had it,” Kerby said.

Seattleite Mecca Irby, now 20, was one such teenager.

Irby had a hard time connecting the high-potency weed she considered a miracle cure for her depression to the disabling sickness that occurred a few years later. On several occasions, she got so ill that even the smell of food made her throw up.

In February 2023, she was finally diagnosed with CHS.

Irby didn’t believe it.

Then, in July 2024, she got so sick she thought she was dying. She came home from a friend’s house around 10 p.m., started throwing up, and could not stop.

“I was just lying in my bed, shaking. My eyes started to roll back into my head,” she said. “My breathing was slowing down. I wasn’t able to control anything. I couldn’t move. My fingers were tingling. I couldn’t feel them. It was scary and I was like, ‘This is not something I can do again.’”

Irby finally accepted her CHS diagnosis — part of a trend that is encouraging to Kerby from Seattle Children’s.

Upon her return to the hospital in 2020, Kerby found that teenagers were self-diagnosing CHS.

“Probably one of the first 10 patients I saw told me she had cannabis hyperemesis. She not only believed she had it [and] knew what it was, but also knew that she could not stop using and was severely addicted to cannabis,” Kerby said. “I no longer have to convince people that marijuana, one, is a drug, and two, is addictive.”

Kerby is the only certified substance use disorder professional who sees patients on Children’s main campus in Seattle. She estimates that 85% of the young people she sees each week have a cannabis use disorder.

Her biggest complaint when it comes to mental health care in Washington state is the lack of treatment for young people dealing with addiction, something that was promised when recreational cannabis was legalized, and the state began collecting 37% excise tax on sales, which in 2024 surpassed $454 million.

Kerby said she’s seen schools turn a blind eye to vape use, because it’s so widespread. When teens do seek help, their options are limited, she said.

“Youth treatment is an abomination in the state,” Kerby said.

The path forward

For people with CHS, the only way to confirm that diagnosis is to quit using cannabis.

As hard as it can be for a lot of people to believe cannabis can be dangerous, and in some cases fatal, it is equally hard for daily cannabis users to quit.

Even Mecca Irby, who believed six months ago she was dying from CHS, has cut back but not completely stopped smoking marijuana.

She now only uses strains that are lower than 30% THC and has cut back to once or twice a week. She hasn’t had a CHS episode in six months.

“It used to be pretty much all day, every day, and I think that’s kind of where it got the best of me,” Irby said.

UW researchers Denise Walker and Ryan Petros have been studying the best way to help young people with psychosis stop using weed, as well as approaches for families of people addicted to cannabis.

Walker said the biggest obstacles they face are the public perception that cannabis is harmless and the struggle to find money to continue their research.

“We need more prevention research that acknowledges the harms of cannabis, particularly with [young people],” Walker said. “We need to, as a state, be rethinking our policies around what we sell and what we allow people to consume. There needs to be a lot done around prevention, but also continued work on treatment. We’re just at the tip of the iceberg at this point.”

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For his part, Don Danielson has lost friends and been ridiculed for speaking out publicly about what happened to his son, he said. He wants people to understand that he is not anti-marijuana.

“We’re not against the use of weed, but we just want people to know that there are consequences now,” Danielson said. “The weed of today is not the weed of yesterday, not by any stretch of the imagination.”

Bridging the divide

For the past six months, Kristen Haley, the public health education liaison at the Washington State Liquor and Cannabis Board, has been attempting to lower the temperature between the cannabis industry and public health officials.

Haley formed a group called the Hybrid High-THC Work Group. She started meeting separately with public health officials and then with cannabis industry leaders. In August she brought the two groups together to talk about how they might work together to regulate high-THC products and protect public health.

“Before these conversations happened, our only exposure to one another in both of these communities was during testimony during [the legislative] session,” Haley said. “We would just get up to the mic and shout at each other and just have this battle, and then we’d go away, and we’d never talk behind the scenes.”

In six sessions with the working group, Haley said she has seen the tone change and people connect on issues that before seemed impossible, areas like preventing youth access and even increasing regulations on high-THC products.

The two sides are getting to know each other. The group is helping both sides recognize the humanity of their counterparts and appreciate their passion and their objections, Haley said.

“I don’t want to paint the picture like we’ve solved the world, and that’s it’s all peace and harmony from now on. But I do think that it has unlocked this potential for us to just have reasonable, grounded, even tempered conversations that we just haven’t been able to do in our state before now,” she said.