This survey study (n=1993) found that in naturalistic (non-laboratory studies) setting, the single worst difficult experience (‘bad trips’) was associated with acute negative effects (aggression, physical harm) and long-term negative (3 cases of both suicide attempt and enduring psychotic symptoms) and positive (increase in well-being) outcomes.
“Acute and enduring adverse effects of psilocybin have been reported anecdotally, but have not been well characterized. For this study, 1993 individuals (mean age 30 yrs; 78% male) completed an online survey about their single most psychologically difficult or challenging experience (worst “bad trip”) after consuming psilocybin mushrooms. Thirty-nine percent rated it among the top five most challenging experiences of his/her lifetime. Eleven percent put self or others at risk of physical harm; factors increasing the likelihood of risk included estimated dose, duration and difficulty of the experience, and absence of physical comfort and social support. Of the respondents, 2.6% behaved in a physically aggressive or violent manner and 2.7% received medical help. Of those whose experience occurred >1 year before, 7.6% sought treatment for enduring psychological symptoms. Three cases appeared associated with onset of enduring psychotic symptoms and three cases with attempted suicide. Multiple regression analysis showed the degree of difficulty was positively associated, and duration was negatively associated, with enduring increases in well-being. The difficulty of experience was positively associated with dose. Despite difficulties, 84% endorsed benefiting from the experience. The incidence of risky behavior or enduring psychological distress is extremely low when psilocybin is given in laboratory studies to screened, prepared, and supported participants.”
“Despite these difficulties, it is notable that 84% of respondents reported having benefited from the experience, with 76% reporting increased well-being or life satisfaction attributed to the experience. Some 60% of respondents considered their experience to be among the top 10 most psychologically personally meaningful experiences of their lives, while 34% and 31% reported the experience in the top five most personally meaningful and spiritually significant, respectively.”
This ties back into earlier research by Griffiths et al (2006) which identified that in their study 67% of participants rated the experience (30mg/70kg of psilocybin) as one of the top five (or top) experience in their lives.