Carbonaro · Journal of psychopharmacology (Oxford, England) 2016 · retrospective cross-sectional survey · n=1993

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

Cited 557 times in the scientific literature.

Level 4 - case-series / case-control

Retrospective cross-sectional online survey of self-selected individuals (case series / cross-sectional analogy)

PubMed 27578767 · doi:10.1177/0269881116662634 · record verified 2026-08-30

What was done

An online survey was completed by 1,993 individuals (mean age 30 years; 78% male) who answered retrospective questions about their single most psychologically difficult or challenging experience (worst "bad trip") after ingesting psilocybin mushrooms. Risk factors, acute behavioral outcomes, seeking of medical or psychological help, and enduring changes in well-being were assessed, including via multiple regression analysis.

What was found

Thirty-nine percent of respondents ranked the episode among the top five most challenging experiences of their lifetime. Eleven percent put self or others at risk of physical harm (associated with higher estimated dose, longer duration, greater difficulty, and lack of physical comfort or social support), 2.6% acted aggressively or violently, and 2.7% received medical help. Among those whose experience occurred >1 year earlier, 7.6% sought treatment for enduring psychological symptoms; 3 cases were linked to onset of enduring psychotic symptoms and 3 to attempted suicide. Experience difficulty correlated positively with dose. Regression showed degree of difficulty positively associated, and duration negatively associated, with enduring increases in well-being. Despite the difficulties, 84% reported benefiting from the experience.

Why it matters

It characterizes the acute behavioral hazards and potential lasting psychiatric complications of difficult psilocybin trips in uncontrolled recreational settings, while identifying lack of social support and high dose as key risk factors.

Limits

The sample relies on retrospective self-report with risk of recall bias and self-selection in an online convenience sample. Psilocybin dose, mushroom identity, and psychiatric histories were not objectively verified, and the sample was heavily male (78%).

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