Adverse experiences resulting in emergency medical treatment seeking following the use of magic mushrooms

Psilocybin-containing mushrooms have long historical use and, in modern times, have drawn renewed research interest because of promising therapeutic signals for conditions such as depression, anxiety and addiction. Pharmacologically, psilocybin acts largely via partial agonism at the 5-HT2A receptor and produces perceptual changes, emotional lability and alterations in sense of self, time and space. Earlier experimental and epidemiological work indicates that, relative to many other recreational drugs, psilocybin is physiologically low in toxicity and rarely causes severe medical harm; nevertheless, acute psychological adverse reactions (for example anxiety, panic, paranoia and disorientation) occur, and there are rare reports of seizures, loss of consciousness and injury related to impaired judgement. Variability in mushroom potency, mixing with other substances and non-optimised set and setting are cited as factors that may increase risk, and the literature on harms remains limited outside controlled experimental settings. Kopra and colleagues set out to quantify and characterise adverse experiences after magic mushroom use that led to emergency medical treatment (EMT) seeking. Using data from the 2017 Global Drug Survey (GDS), the study aimed to estimate the 12-month prevalence and per-event risk of EMT seeking among past-year mushroom users, to identify demographic and use-related predictors, and to describe symptom profiles, recovery time, concomitant substance use, perceived reasons for incidents and subsequent changes to substance use.

This study analysed responses to the Global Drug Survey (GDS) 2017, an anonymous, encrypted online survey promoted via social media, media partners and harm-reduction organisations between November 2016 and January 2017 in 10 languages. GDS employs self-nominating, non-probability sampling designed to reach people who engage in less common or stigmatised drug practices. Multi-institutional ethical approvals were obtained and the authors accessed GDS demographic and psychedelics sections under a data-sharing agreement. Participants reported lifetime and recency of use for a wide list of substances, including magic mushrooms. Those reporting past-year mushroom use were asked about days of use in the last 12 months, whether their first use occurred in the past year, the typical number of mushrooms taken on a day of use, and whether they had sought EMT following mushroom use in the past year. The survey did not record the number of separate EMT incidents per respondent. Respondents who indicated EMT seeking were asked about a checklist of 21 psychological and physiological symptoms, the number of mushrooms consumed during the incident session, other substances used in the lead-up, symptom duration, hospitalisation, perceived reasons for the incident (select up to three from six options) and impact on subsequent substance use. Participants could skip items. For the primary risk estimate, the per-event risk of EMT seeking was calculated as the number of past-year EMT seekers divided by the estimated total number of times magic mushrooms were used among past-year users; the mean past-year use frequency was used to approximate total uses. Because outcome variables were non-normally distributed, non-parametric tests were applied: Mann–Whitney U tests compared continuous measures (age, past-year frequency, typical number of mushrooms) between EMT seekers and non-seekers, while Pearson’s Chi-square or Fisher’s exact tests assessed categorical associations (gender, first-time use, presence of lifetime mental health diagnosis). Two multiple correspondence analyses (MCA) were performed to explore patterns among self-reported symptoms and among perceived reasons for incidents. Analyses used complete case analysis and were performed in SPSS IBM Statistics 26.

GDS 2017 collected 119,108 responses. Of respondents, 29,124 (24.5%) reported lifetime magic mushroom use and 12,534 (43.0% of lifetime users) reported use within the past year. Among the 9,233 past-year users who answered the EMT question, 19 (0.2%) reported having sought emergency medical treatment following magic mushroom use in the past year. Using a mean past-year use of 3.72 times (SD = 13.1) to estimate 34,347 total past-year mushroom uses in the sample, the per-event risk was calculated as 0.00055, equivalent to 0.06% or roughly 1 in 1,800 mushroom intakes leading to EMT seeking. A completer subanalysis (1,895 past-year users who completed the whole survey) showed a 98% response rate to the EMT question and an EMT prevalence of 0.3% (6/1,857), indicating limited evidence of major attrition bias. Age was the only variable significantly associated with EMT seeking: median age of EMT seekers was 19 years (IQR 18–23) versus 23 years (IQR 20–27) for non-seekers (Mann–Whitney z = 3.09, p = 0.002). There were no significant differences in EMT prevalence by lifetime mental health diagnosis (0.2% vs 0.2%, p = 0.546), gender (men 0.2% vs women 0.2%, p = 1.00), first-time use in the past year (0.2% vs 0.2%, χ2(1) = 0.43, p = 0.512), typical number of mushrooms consumed (median 4.0 in both groups, Mann–Whitney z = 1.768, p = 0.077) or past-year frequency of use (median 2.0 in both groups, Mann–Whitney z = 1.479, p = 0.139). Among the 19 EMT seekers, the median number of reported symptoms was 5. The most frequently endorsed symptoms were anxiety/panic (68%), paranoia/suspiciousness (68%), seeing/hearing things (42%) and passing out/unconscious (37%). MCA revealed symptom clusters: anxiety and paranoia clustered together; perceptual disturbances clustered with extreme agitation; palpitations, overheating, self-harm and difficulty breathing tended to co-occur; and a cluster including passing out, seizures, sweating, confusion, memory loss and subsequent very low mood was identified. Eight of 19 (42%; 95% CI 20–64%) were admitted to hospital. Recovery times were short: all but one respondent reported returning to normality within 24 hours, and all had recovered within seven days. For the incident session, the median number of mushrooms consumed was 10.0 (IQR 2.0–33.8). Regarding concomitant substances, 42% reported no other substances, 37% reported cannabis and 32% reported alcohol use during the session. When asked about perceived reasons, the most common attributions were wrong mindset (47%), wrong place/setting (37%) and mixing with other substances (37%); MCA suggested mindset and mixing were often reported together. After the incident, 58% of EMT seekers reported having cut down their mushroom use, 37% reported no change, and 16% reported reducing other illicit drug or alcohol use (0% reported increases).

Kopra and colleagues interpret the findings as confirming that emergency medical presentations after magic mushroom use are rare and typically short-lived. The study’s 12-month prevalence of EMT seeking among past-year users was 0.2%, with a per-event risk of approximately 0.06% (about 1 in 1,800 intakes). Psychological symptoms predominated—chiefly anxiety/panic and paranoia—which aligns with prior reports on psychedelic challenging experiences. Nonetheless, a notable minority of respondents reported physiological events such as loss of consciousness (37%), difficulty breathing (32%) and seizures (26%), and the aetiology of these events remains uncertain in the survey context. The authors highlight plausible triggers mentioned in the discussion: rapid blood-pressure changes, dehydration or undernutrition, transient memory loss or sleep, cardiac arrhythmias at high doses and interactions with other substances or medications (lithium is singled out in the literature as linked to severe reactions). They caution that the survey cannot determine whether reported seizures were epileptic or psychogenic. Polysubstance use was common among EMT seekers and is discussed as a potential contributor to adverse reactions; cannabis in particular is noted as sometimes exacerbating challenging psychedelic experiences rather than calming them, with prior studies cited for mixed or dose-dependent effects. The importance of ‘‘set and setting’’ was reinforced: wrong mindset and wrong place were frequently endorsed as reasons for incidents. Younger age emerged as the sole predictor of EMT seeking; the authors suggest possible explanations including lower risk aversion, greater impulsivity and developmental differences in emotional regulation, and note that prior psychedelic experience did not protect against incidents. Comparisons with their parallel LSD analysis show a lower prevalence of EMT seeking following mushroom use (approximately fivefold lower), which the authors attribute to differences in potency, difficulty of accidental overdose with mushrooms, and shorter duration of psilocybin effects versus LSD. The low incidence of EMT events is acknowledged as both reassuring and a limitation: small numbers limited power to detect predictors and to analyse rare but serious outcomes. Other limitations discussed include self-nominating non-probability sampling with potential volunteer bias, retrospective self-report and recall biases, possible selective non-response to the EMT question, absence of an ‘‘other’’ open-response option for perceived causes, inability to verify substance purity or dose, and the crudeness of ‘‘number of mushrooms’’ as a consumption metric. The authors also note that survey data cannot establish the precise circumstances leading to EMT seeking or disentangle the contributions of psilocybin versus other mushroom constituents. Despite these caveats, the investigators conclude that most adverse reactions were brief and that harm-reduction information and safer use practices are likely important to prevent incidents. They judge the results reassuring from a public-health standpoint and suggest the findings support reconsideration of psilocybin’s legal status to facilitate clinical research and harm-reduction services.