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How common hard experiences are, and how long they last

The question here is how often people report a hard experience with a psychedelic, and how long it lasts, according to published studies. The numbers depend on who was asked and how. This card reports what others have published.

Published Information current to 8 November 2026Review due by 6 February 2027

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The short answer

How often do people report a hard experience with a psychedelic, and how long does it last?

The numbers depend on who was asked and how. In one laboratory study of 18 healthy volunteers, 7 rated extreme fear, fear of insanity or feeling trapped at some point. In a US online survey of 613 lifetime users of classic psychedelics, 59.1% said they had never had a challenging experience. Neither figure is a rate for healthy adults in general, and the two cannot be compared directly.

What was found?

Reported findings, not recommendations. Each figure names its group and method. Associations are not causes.

  • Laboratory, healthy volunteers. In a double-blind study, 18 healthy adults (17 hallucinogen-naive) each had five sessions with placebo and psilocybin at 5, 10, 20 and 30 mg per 70 kg, after eight hours of preparation and with two monitors. These are the amounts the study gave, not limits. Seven (39%) rated extreme fear, fear of insanity or feeling trapped at some point (none at placebo or the two lower amounts, 1 at 20 mg, 6 at 30 mg). Eight (44%) had delusions or paranoid thinking (1 at 20 mg, 7 at 30 mg). Monitors rated strong anxiety for a mean total of 11 minutes of six hours at 30 mg and under 2 minutes at 20 mg, a mean across all 18 and not a typical length. The authors say the volunteers were screened, prepared and monitored, and that the findings should not be read as applying to casual use. Source 1, level 1
  • Review of trials. A 2024 review of 114 studies (3,504 participants, 1,726 of them healthy) found no serious adverse event among healthy participants. In a supplement table, anxiety of any severity in psilocybin groups was reported by 23.9% (95% CI 14.2 to 37.3) across 11 groups of 314 people the authors labelled healthy, and by 21.1% (13.1 to 32.1) across 15 groups of 489 outpatients with neuropsychiatric conditions. The authors write that the data cannot be meaningfully generalised to unsupervised use. Source 2, level 1
  • Naturalistic survey. In a 2021 US online survey with quotas on sex, age and ethnicity, 613 of 2,822 respondents were lifetime users of classic psychedelics. 59.1% reported never having a challenging experience, 23.3% rarely, 13.1% occasionally and 4.6% regularly or frequently. 8.9% reported impairment lasting longer than one day. A symptom checklist was endorsed by 57.1%, a different question. Source 3, level 1
  • Survey of people who reported a bad trip. In a 2013 online survey of people who reported a hard experience with mushrooms, 1,339 had it at least a year earlier. Of these, 24% reported at least one of five symptoms (fear, anxiety, depression, paranoia or other) lasting a week or longer that they attributed to the session. The authors write that frequency cannot be estimated from people who chose to report one. Difficulty went with amount only weakly (correlations 0.11 and 0.18). How long the hard part lasted is on the card When a session gets hard. Source 4, level 1

What is not known?

Searches on 8 November 2026 covered PubMed (12 strings) and Europe PMC (6, two for preprints), several scanning only the first 15 to 25 titles. PsycINFO, Embase and Google Scholar were not searched. “Not located” means no source read in full showed it.

  • A rate of hard experiences for a defined group of healthy adults in unsupervised settings. Not located.
  • How long hard states last in naturalistic users outside self-selected samples. Not located.

What this card does not say

  • It does not say how likely a hard experience is for anyone, or rank any amount, setting or group by risk. It sets no standard of care. No amount named here is a limit or a threshold. Lasting difficulties beyond weeks are a separate topic in preparation.
  • Related cards: when things go wrong, when a session gets hard and mental health history.

Send a correction

If this card reports something wrongly, tell us. Write to main@metanoia-ca.org and keep the card name in the subject line. Accounts of what happened in a session belong in the field reports channel, not in email. Please leave out names and anything that identifies a person or a place. We read every message.

Where does this come from?

Grade key: 1 = peer-reviewed publication or official record, reported as the source states it. A grade names the type of source and says nothing about its quality. “Read in full” means Metanoia read every sentence of the text cited on the date given, and any part not read is named.

Review due by 6 February 2027.

  1. Griffiths RR, Johnson MW, Richards WA, Richards BD, McCann U, Jesse R. Psilocybin occasioned mystical-type experiences: immediate and persisting dose-related effects. Psychopharmacology 2011. DOI 10.1007/s00213-011-2358-5. PMID 21674151. Grade 1. Double-blind dose-effect study, 18 volunteers. Read in full 8 November 2026 (author manuscript PMC3308357, tables included). Figures and reference list not read.
  2. Hinkle JT, Graziosi M, Nayak SM, Yaden DB. Adverse events in studies of classic psychedelics: a systematic review and meta-analysis. JAMA Psychiatry 2024. DOI 10.1001/jamapsychiatry.2024.2546. PMID 39230883. Grade 1. Systematic review and meta-analysis. Read in full 8 November 2026. Of the supplement, only the table splitting psilocybin groups by population (eTable 3) and its notes were read, and the rest was not read line by line. The split figures above rest on that table alone.
  3. Simonsson O, Hendricks PS, Chambers R, Osika W, Goldberg SB. Prevalence and associations of challenging, difficult or distressing experiences using classic psychedelics. J Affect Disord 2023. DOI 10.1016/j.jad.2023.01.073. PMID 36720405. Grade 1. Cross-sectional online survey. Read in full 8 November 2026 (author manuscript). Supplement not read.
  4. Carbonaro TM, Bradstreet MP, Barrett FS, MacLean KA, Jesse R, Johnson MW, Griffiths RR. Survey study of challenging experiences after ingesting psilocybin mushrooms. J Psychopharmacol 2016. DOI 10.1177/0269881116662634. PMID 27578767. Grade 1. Online survey of people who reported a bad trip. Read in full 8 November 2026. Figures not read.