Half of psychedelic-related poison center cases result in medical treatment, study finds

More than half of psychedelic exposures reported to poison centers across the U.S. between 2012 and 2022 had symptoms that required medical treatment or resulted in residual or prolonged symptoms or death, according to a new study from researchers at the University of Colorado School of Medicine.

As the legal landscape around psychedelic substances shift — like it has in Colorado and Oregon — the need for data persists in understanding real world use and how it’s affecting users.

“Every person who uses psychedelic substances is different and reacts differently because they alter your perception, mood, and cognition. One person’s desired effect may be another’s undesired effect,” says Mark Simon, MD, lead author on the study and senior instructor of emergency medicine.

“Because of the mechanisms of each of these agents, particularly through serotonergic modulation, some of the complications that we see are either intrinsic to the substance or caused by excess serotonin,” he continues. “So it's very different, depending on who gets into these and what their goals are for the psychedelic substance.”

Of nearly 55,000 Nation Poison Data System cases analyzed by the researchers, 42% had moderate effects that were pronounced or prolonged effects that usually require treatment, 8% had major effects that were life-threatening or resulted in significant residual disability, and 0.5% of cases resulted in death.

Approximately 41% of cases had concomitant exposures, meaning users were using other substances, such as pharmaceuticals, drugs, or alcohol, when exposed to a psychedelic substance.

Diverse agents with similar effects

Researchers found that exposure severity did not increase over the 10 years they studied. Cardiovascular effects were common, seen in more than 68% of cases.

Additionally, the analysis shows that 62% of cases that were referred to a health care facility needed at least one medical therapy, usually a sedative. Simon says this number is meaningful, but it’s important to remember that most psychedelic exposures aren’t reported to poison centers and aren’t treated in a health care facility.

“Most exposures happen at home and people don’t come into contact with the medical system. The subset of the population that we were looking at here was only those that had some reason to seek out medical care, and that the health care facility felt that it was warranted to reach out to the poison center. This usually was because of a severe, atypical, or unexpected effect,” he explains.

A subsection of the population, 6.9%, required ventilation or intubation. Respiratory interventions, such as supplemental oxygen, positive pressure ventilation, or intubation were required in 10.3% of exposures.

Knowing the range of outcomes for a range of agents, even if some are uncommon is important for medical care givers, Simon says. For example, some agents, like ketamine and ketamine analogs, are more likely to lead to respiratory complications, compared to hallucinogenic mushroom or plants.

“Some agents have similarities in their mechanism, but psychedelic substances are a pretty diverse group. Lumping them all together can be problematic. That is why we attempted to separate agents based on class as these are important to think about separately,” Simon says.

Increasing exposures expected to continue

In 2015, 4.7 million Americans said they’ve used a hallucinogen in the last year. That number almost doubled, up to 8.5 million in 2022.

“We expect that to continue increasing,” Simon says. “We saw even higher increases in states that have legalized and decriminalized psychedelics.”

Over the course of the study period, Colorado became a frontrunner in legal changes of some psychedelic substances. Denver was the first city in the U.S. to decriminalize psilocybin in 2019 and in 2022 Colorado followed up by decriminalizing the growth, possession, and sale of natural psychedelics. In 2020, Oregon legalized the administration of psilocybin through its license centers.

“It’s important to think about and study complications as policy and regulations change,” Simon says. “This study is just one puzzle piece in a much larger picture of what effects psychedelic substances can have.Clinical trials can display what’s happening in ideal circumstances, where these agents are showing promise in the treatment of certain medical conditions. That’s important, but so is real world use and knowing how people are reacting to recreational use and outside of clinical trials.”