Survey study of challenging experiences after ingesting psilocybin mushrooms: Acute and enduring positive and negative consequences

Psilocybin, the principal psychoactive compound in Psilocybe and related mushrooms, has a long history of use in certain cultural and religious contexts. Previous literature indicates that psilocybin has low physiological toxicity and low addictive potential, but it can occasion acute distressing psychological reactions and, more rarely, persisting adverse psychiatric outcomes. Emergency-department and poison-centre data show that medical presentations involving psilocybin are uncommon relative to many other drugs, yet case reports and anecdotal evidence document instances of short-term fear, risk-taking behaviour, and longer-term psychiatric problems following non‑clinical use. This study set out to characterise psychologically difficult or challenging experiences—commonly described as “bad trips”—following ingestion of psilocybin mushrooms. Carbonaro and colleagues conducted a large anonymous internet survey asking respondents to report in detail on a single worst challenging psilocybin session, including demographics, set and setting, dose and duration, acute and enduring negative and positive consequences, and use of strategies to alleviate the experience. The aim was to quantify the nature, acute harms, and longer-term outcomes of difficult psilocybin experiences occurring outside laboratory contexts and to examine factors associated with increased risk of harm.

Participants were recruited primarily through psychedelic-focused websites, email invitations, and online social networks between January and July 2013. Interested individuals were directed to an online SurveyMonkey questionnaire describing the study aims; participation was anonymous and voluntary. The Johns Hopkins Institutional Review Board approved the procedures. Inclusion required being at least 18 years old, English fluent, reporting a psilocybin mushroom dose that produced moderate to strong effects, endorsing having had a psychologically difficult/challenging experience with psilocybin (a “bad trip”), reporting that the selected experience occurred aged 18–70 outside a university or hospital study, and not having previously completed the survey. Respondents were instructed to answer about their single most psychologically difficult session. Cases attributed to co‑consumption of substances other than psilocybin, or whose open‑ended comments raised validity concerns, were excluded. The survey took roughly 45 minutes (median completion time 59 minutes) and included demographic items, lifetime hallucinogen use, session‑specific questions (estimated dose, set and setting, duration, intentions, presence of a guide, co‑use of other drugs), and three psychometric instruments commonly used in psychedelic research: the Hallucinogen Rating Scale (HRS), the 30‑item Mystical Experience Questionnaire (MEQ30), and selected subscales of the 5D‑ASC. Qualitative retrospective ratings solicited perceived difficulty, personal meaningfulness, spiritual significance, and change in well‑being attributed to the session. Optional open‑ended written comments were collected. Statistical analyses used descriptive statistics, Pearson correlations to explore associations among difficulty, duration, meaning, spiritual significance and well‑being, and multiple regression to examine the relative contributions of difficulty and duration on those outcomes. Correlations and binary logistic regression (odds ratios) evaluated relationships between dose, setting, concurrent drug use, age, past hallucinogen experience, and endorsement of putting self or others at risk. For enduring effects, analyses focused on participants whose session occurred at least 1 year prior to survey completion. The survey flow is reported: 5,850 started the survey; after exclusions and non‑completion, 1,993 provided usable data.

Sample and session characteristics: Of the 1,993 respondents analysed, mean age at survey was 29.8 years and 78% were male; 89% identified as White and 51% had a college or graduate degree. Median lifetime uses of psilocybin prior to the chosen session fell in the 6–10 range, and 93% had used psilocybin more than twice. The median reported weight of dried mushrooms among those who knew weight was 4 g (n = 1,203); fresh mushroom median weights clustered at 21–30 g (n = 148). Sixty‑eight percent reported taking a moderately high or high dose for the session, and 36% were attempting a larger than usual dose. Session contexts varied: 25% were alone, 24% with one person, 39% with a few people, 9% in a small/medium group and 4% in a large gathering. Only 25% had any sitter or guide present, and 2.7% reported a trusted sober guide experienced in psychedelic support. Cannabis or alcohol use immediately before or during the session was reported by 53% and 19%, respectively. Median reported age at the chosen session was 23.3 years, and the session occurred on average 6.5 years before survey completion. Qualitative outcomes and psychometric scores: Participants rated the chosen session as highly challenging: 62% considered it among the top 10 most psychologically difficult episodes of their lives, 39% among the top five, and 11% as the single most challenging. Despite this, many reported positive longer‑term effects: 76% indicated the session led to increases in well‑being or life satisfaction and 84% reported benefiting from the experience. Thirty‑four percent and 31% rated the session among the top five personally meaningful and spiritually significant experiences of life, respectively. HRS subscale means (SEM) were reported (e.g. Intensity 2.62 (0.01), Perception 2.54 (0.02)). MEQ30 subscale means included Ineffability 69.24 (0.58) and a total score mean 50.26 (0.54); 20.5% fulfilled criteria for a “complete” mystical experience (scores ≥60% on each MEQ30 subscale). Relations among difficulty, duration, dose and setting: Duration of the difficult portion correlated positively with degree of difficulty (r = 0.30) but correlated negatively, or less strongly, with personal meaning, spiritual significance and enduring well‑being. Degree of difficulty correlated positively with personal meaning (r = 0.41) and, to a lesser extent, with spiritual significance and enduring well‑being. Multiple regression showed that higher difficulty predicted greater personal meaning, spiritual significance and enduring increases in well‑being, whereas longer duration predicted lower ratings on those outcomes. Risk and acute harms: Endorsement of putting self or others at risk of physical harm was reported by 10.7% of respondents; 2.6% reported behaving in a physically aggressive or violent manner and 2.7% sought medical help at a hospital or emergency department during the occasion. Endorsement of risk was positively correlated with estimated dose (HRS item) (r = 0.071, p < 0.01), degree of difficulty (r = 0.154, p < 0.001), and duration (r = 0.157, p < 0.001). In logistic regression, better physical comfort reduced odds of endorsing risk (odds ratio = 0.562, p < 0.001, 95% CI 0.416–0.760) and greater social support also reduced odds (odds ratio = 0.657, p = 0.004, 95% CI 0.493–0.875). Weight of dried mushrooms, age, past hallucinogen experience, emotional state before ingestion, and use of cannabis or other mood‑altering drugs were not significantly associated with endorsement of risk. Strategies to alleviate the experience: Most participants (91%) tried at least one strategy to stop the challenging experience. Common attempts included calming the mind (69%) and changing location (63%); 33–40% tried shifting body posture, changing music or the social environment, or asking for help. About 25% used cannabis and smaller proportions used alcohol (5%) or another drug (3%). Participants judged these strategies to be modestly effective overall: on average, strategies reported as having helped substantially were about 57% as frequent as strategies attempted. Suicidality and enduring problems: Independent review of open‑ended comments identified both increased suicidality (five cases) and decreased suicidality (six cases) attributed to the psilocybin session. Three respondents described suicide attempts or severe self‑harm behaviour linked temporally to their session. To assess enduring effects, analyses focused on participants whose session was ≥1 year prior (n = 1,339). In that subgroup, 24% reported experiencing one or more negative psychological symptoms lasting ≥1 week attributed to the session (fear 13%, anxiety 16%, depression 12%, paranoia 9%, other 12%); 10% reported symptoms lasting ≥12 months and 7.6% sought professional treatment for these symptoms. Of those who sought treatment after the session, 28 individuals (2.1% of the 1,339) had reported no prior symptoms or treatment. Prior treatment history strongly predicted post‑session treatment: 14.3% of those with prior treatment sought help after the session compared with 6% without prior treatment (p < 0.001). Review of open‑ended data identified three cases in which respondents attributed onset of enduring psychotic symptoms to the challenging psilocybin session; all three were White males aged 18–21 at the time of the session and reported no prior psychotic symptoms.

Carbonaro and colleagues interpret their findings as evidence that psychologically difficult experiences after taking psilocybin mushrooms can lead to both acute harms (dangerous behaviour, need for emergency care) and enduring psychological problems, while also producing lasting benefits for many individuals. The survey of nearly 2,000 respondents who reported on their single worst challenging session found that although substantial proportions rated the session as highly meaningful or spiritually significant and reported increases in well‑being, nontrivial percentages reported acute risk‑taking (11% putting self or others at risk), emergency care (2.7%), aggressive behaviour (2.6%), and longer‑term treatment‑seeking (7.6% among those whose session occurred ≥1 year earlier). Three cases were reported as possibly linked to onset of enduring psychotic symptoms and three to attempted suicide. The authors place these results in the context of controlled laboratory research, where rates of acute and enduring problems are substantially lower. They note that only a small minority (2.1%) of survey respondents had session conditions approximating laboratory standards (conducive emotional state, physical comfort, social support and trusted sober guide). Reported risk factors in the survey included larger estimated dose, greater subjective difficulty and longer duration of the difficult experience, and lack of physical comfort and social support. From a therapeutic perspective, the authors suggest that interventions during a challenging experience might usefully prioritise reducing the duration of acute difficulty rather than attempting to blunt peak intensity, since duration was negatively associated with later meaning, spiritual significance and well‑being. Several limitations are acknowledged. As an anonymous internet survey, the data rely on self‑report and the veracity of respondents cannot be independently verified; non‑completion rates were high and the sample lacked demographic diversity (78% male, 89% White, 87% with some college). The recruitment strategy, focused on psychedelic‑oriented online media, produced a sample enriched for individuals who had experienced a challenging session and who may retain favourable interest in psychedelics, limiting generalisability and precluding population‑level prevalence estimates. The authors also note the survey did not assess hallucinogen persisting perception disorder specifically. Finally, differences between reported median doses (4 g dried, roughly estimated as ~25 mg psilocybin equivalent) and laboratory dosing contexts are discussed: although some psychometric indices (HRS Intensity) were comparable to controlled 20 mg/70 kg administration, MEQ30 scores and rates of “complete” mystical experience were lower in the survey sample than in lab studies, consistent with the survey focusing on the most challenging session rather than a randomly sampled session. Overall, the investigators conclude that psychologically difficult psilocybin experiences occurring outside controlled settings can involve acute danger and enduring harm for a minority, but also that many participants report lasting benefit. They emphasise that risks appear to be extremely low in laboratory studies that employ screening, preparation, and supportive monitoring during and after psilocybin administration, reinforcing the importance of set and setting when psilocybin is used clinically or recreationally.