Hospital Visits For Hallucinogens Linked to Sharp Rise in Mania

Study finds bipolar diagnoses far more common among hallucinogen-related cases

–A major Canadian study tracking more than 9 million people reports that those who land in the hospital after using hallucinogens face a dramatically higher risk of developing mania or bipolar disorder in the following years.

Researchers at the University of Ottawa and ICES found that people who required emergency care involving hallucinogens were 25 times more likely to experience a manic episode within three years compared to people of the same age and sex in the general population. The findings were published this week in PLOS Medicine.

The study arrives as the use of psychedelics — including LSD, psilocybin, MDMA, ketamine, and others — surges across North America. While many people turn to these drugs for recreation or for unapproved therapeutic uses, the long-term mental health risks remain poorly understood.

Within three years, people requiring acute care involving hallucinogen use were six times more likely to have an episode of mania, and 4 times more likely to be diagnosed with bipolar disorder compared to the general population, the authors wrote.

A closer look at who is most at risk

Led by Dr. Daniel Myran, the research team analyzed health records for every Ontario resident aged 14 to 65 between 2008 and 2022. Among the 9.3 million people studied, 7,285 had an emergency department visit or hospital stay involving hallucinogens.

Most of these visits were for harmful use, acute intoxication, poisoning, dependence, or hallucination-related psychosis. Some 35% involved harmful use, while about 1 in 5 involved poisoning from the substances.

Compared with the general population, individuals in the hallucinogen-care group had higher rates of prior mental health treatment, past substance use, and homelessness. Nearly 62% had a previous substance-use–related hospital visit, and almost 50% had been treated for a mental health condition in the previous five years.

Mania risk surged in the months after the ER visit

Of those who had a hallucinogen-related acute care visit, 1.43% developed mania within three years — compared with 0.06% of the matched general population.

After adjusting for multiple factors, the authors found a weighted hazard ratio of 5.97, meaning these patients remained six times more likely to experience mania even when compared with people who shared similar mental health and demographic backgrounds.

Mania risk was highest soon after the hospital visit. As the authors noted, “Risk of mania rose most rapidly in the period immediately following the acute care for substance use.”

The study also examined new bipolar disorder diagnoses. Within three years, 2.50% of individuals with hallucinogen-related care were diagnosed with bipolar disorder, compared with 0.11% of the general population — a more than 20-fold difference before adjusting for confounders.

Not just psychedelics — and not proof of causation

The study could not identify which specific drugs were used because most hospital codes do not distinguish between substances. Hallucinogens in the dataset included dissociatives such as ketamine and PCP as well as serotonergic psychedelics like psilocybin and LSD.

The authors cautioned that the findings apply only to patterns of use that lead to medical crises. “The main limitation of the study is that the findings may not apply to the majority of people who use hallucinogens who do not require urgent healthcare,” they wrote.

It is also unclear whether the drugs caused the mania or whether people already at high risk for bipolar disorder were more likely to use hallucinogens in risky ways.

Unmeasured factors — such as genetics, trauma history, and detailed drug dosing — may also play a role.

Why the findings matter now

The study adds weight to concerns raised by clinicians and researchers who have warned that psychedelic use may provoke mania in people predisposed to bipolar disorder. As the authors emphasized, the rise of both medical and recreational hallucinogen use underscores the need for better long-term safety data.

“These findings suggest the need for ongoing caution regarding hallucinogen use in individuals at risk of bipolar disorder,” the researchers concluded.

Source: Myran DT et al., “Hospital-based care for hallucinogens and risk of mania and bipolar disorder,” PLOS Medicine, Dec. 2, 2025. journal.pmed.1004805

Note from the editor: I have experimented on rare occasion with some of the hallucinogenic drugs. Most were years before my first manic episode, so my own experience may or may not be relevant. I have met others with bipolar who have used these drugs before. – Alex Rowan

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