Receipt of acute care for hallucinogen use predicts greater mortality risk within 5 years

Key takeaways:

• Harmful hallucinogen use or hallucinogen poisoning were the most common reasons for acute care.
• Risk for mortality was greater among individuals who received acute care for hallucinogens vs. alcohol.

Individuals in Canada who received hospital care for hallucinogen use had greater 5-year mortality risk, especially from suicide, compared with the general population, according to a study published in Canadian Medical Association Journal.

“In Canada, an estimated 5.9% of people used a psychedelic such as LSD or psilocybin in 2023, with use as high as 13.9% in people aged 20 to 24 [years],” Daniel T. Myran, MD, MPH, Canada Research Chair in Social Accountability at University of Ottawa, adjunct scientist at the Institute for Clinical Evaluative Sciences, investigator at Bruyère Health Research Institute and associate scientist at The Ottawa Hospital, said in a related press release.

The researchers noted that similar increases in use have been observed in the U.S.

Because data are lacking regarding hallucinogen use and their risk for severe adverse events such as death outside of controlled studies, the researchers conducted a retrospective cohort study of participants eligible for Canada’s public health insurance program to evaluate if receipt of hospital treatment involving hallucinogen increased risk for all-cause mortality vs. the general population and individuals treated for incidents involving other substances.

Of 11.4 million participants aged 15 years and older who were living in Ontario between 2006 and 2021, 7,953 (0.07%; male, 70.3%; mean age, 27.8 years) had an incident acute care event involving hallucinogens, mostly for harmful use (35.1%) or hallucinogen poisoning (20.9%). This group was matched 1:10 by age, sex and index date to individuals in the general population (n = 77,101).

Median follow up was 7 years (interquartile range, 3-11).

The researchers found that, compared with the matched general population, the hallucinogen group appeared more likely to live in low-income neighborhoods, have several chronic conditions, and have received outpatient mental health care or acute care for substance use or a mental disorder in the past 3 years.

Within 5 years, a greater proportion of individuals in the hallucinogen group died compared with the general population group (6.1% vs. 0.6%), equating to a 9.7-fold greater increase.

After overlap weighting for previous substance abuse, mental health care and sociodemographic factors, the researchers found that individuals who had acute care involving hallucinogens were more than twice as likely to die within 5 years compared with the general population (HR = 2.57; 95% CI, 2.09-3.15). They observed a similar increase in mortality risk in sensitivity analyses that excluded people with any outpatient or acute care for mental health or substance use in the past 3 years (HR = 3.25; 95% CI, 2.27-4.63).

Further, in secondary analyses, the researchers found that individuals who received acute care for alcohol were at lower risk for death (HR = 0.89; 95% CI, 0.81-0.98) than those who received acute care for hallucinogens. On the other hand, risk for death was greater for individuals who received acute care for stimulants (HR = 1.1; 95% CI, 1.01-1.21) or opioids (HR = 1.36; 95% CI, 1.24-1.5).

Finally, individuals in the hallucinogen group appeared at greater risk for all causes of death studied in fully adjusted analyses, especially unintentional drug poisoning (HR = 2.03; 95% CI, 1.02-4.05), suicide (HR = 5.23; 95% CI, 1.38-19.74), respiratory disease (HR = 2.46; 95% CI, 1.18-5.11) and cancer (HR 2.88, 95% CI 1.61-5.14).

The researchers noted several limitations to this study, including that data were lacking regarding hallucinogen type and patterns of usage.

Based on their results, the researchers theorized that hallucinogen use in vulnerable people in nonmedical settings may increase suicide risk or lead to the development of severe mental illnesses.

“The findings highlight the need for ongoing investigation and dissemination of both potential benefits and risks from hallucinogen use, particularly for use outside clinical trial settings, given rapid increases in general population use,” they added.

Reference:

• Hallucinogen use linked to 2.6-fold increase in risk of death for people needing emergency care. https://www.eurekalert.org/news-releases/1075010. Published March 3, 2025. Accessed March 12, 2025.