A new study published in PLOS Mental Health highlights a complex relationship between the intense psychological effects of ayahuasca and users’ long-term mental health. Drawing from a global survey, the research found that some adverse effects commonly experienced after using ayahuasca—such as feeling down or disconnected—were tied to poorer mental health, especially in people with a history of depression. However, other effects traditionally labeled as negative, such as visual distortions, were associated with better mental health outcomes.
The findings suggest that not all challenging experiences during or after ayahuasca use should be considered harmful, and that context, individual vulnerability, and integration support play key roles in shaping outcomes.
Ayahuasca is a plant-based psychedelic brew with a long history of ritual use in Indigenous Amazonian traditions. It typically combines the vine Banisteriopsis caapi with DMT-containing plants like Psychotria viridis. The combination produces strong hallucinatory and emotional effects, often described as spiritually significant. In recent years, ayahuasca has gained attention in Western countries as an alternative treatment for mental health conditions such as depression, anxiety, and substance use disorders. While research on its therapeutic potential has grown, much less is known about its adverse effects and how these experiences may influence long-term psychological well-being.
“While numerous studies have highlighted ayahuasca’s potential mental health benefits, adverse effects have received much less scientific attention,” said study author José Carlos Bouso, the scientific director at ICEERS. “Our motivation was to fill that gap by exploring how commonly these effects are reported, what they actually consist of, and whether they truly constitute ‘negative’ outcomes. Ultimately, our aim is to help facilitators and participants better understand and prepare for challenging experiences so they can be handled constructively, and ideally, avoided when harmful.”
To address this gap, the researchers analyzed data from the Global Ayahuasca Survey, an online questionnaire completed by 10,836 individuals from more than 50 countries between 2017 and 2019. Participants were over 18 and had used ayahuasca at least once. The survey collected information on their demographics, history of mental health diagnoses, ayahuasca use patterns, subjective experiences during ceremonies, and mental health status at the time of the survey. Researchers focused on adverse psychological states reported in the weeks or months after ayahuasca use and used statistical and machine learning tools to examine how these experiences related to current mental health.
After accounting for missing data and applying statistical preprocessing, the final sample included 5,400 participants. The average age was about 41 years, nearly half were women, and most had used ayahuasca more than 30 times. Mental health was assessed using the SF-12 survey, a widely used measure that reflects psychological functioning. Participants were also asked to rate whether they experienced various post-ayahuasca effects, including depression-like symptoms, anxiety, feelings of disconnection, hallucinations, and spiritual distress.
One of the most consistent findings was that individuals with a history of depression or anxiety were more likely to report increases in adverse states after using ayahuasca. Those with depression were especially prone to reporting feelings of hopelessness, lack of interest in activities, and emotional disconnection. These same symptoms were strongly associated with poorer mental health outcomes at the time of the survey.
However, some of these experiences may reflect a resurfacing of previous conditions rather than entirely new effects caused by ayahuasca. The researchers note that understanding individual vulnerabilities is essential for anticipating these outcomes.
In contrast, other effects often described as adverse—such as visual distortions or hallucinations—were not linked to poorer mental health. In fact, participants who reported these experiences tended to have better mental health scores. Visual distortions in particular were positively associated with long-term well-being, especially among those who rated their ceremonies as spiritually significant. These findings suggest that experiences often labeled as “negative” might play a constructive role, depending on how they are interpreted and integrated.
“One surprising insight was that we may need to reconsider what we classify as ‘adverse effects’ when studying psychedelics,” Bouso told PsyPost. “In traditional pharmacology, symptoms like confusion or perceptual distortions are often treated as negative. But in the context of ayahuasca and similar medicines, these experiences may actually form part of the healing process.”
The setting and cultural context of ayahuasca use also influenced outcomes. Participants who drank ayahuasca in traditional settings—such as Indigenous ceremonies or ayahuasca churches—were less likely to report emotional distress after the experience compared to those in non-traditional or informal contexts. People from non-traditional countries (outside South America) were more likely to feel emotionally disconnected after ceremonies, which in turn related to lower mental health. This highlights the importance of preparation, guidance, and cultural grounding in shaping how people make sense of their experiences.
Another important factor was the emotional tone of the ceremony. Participants who described their ayahuasca experience as spiritually meaningful tended to report fewer depression-like effects and better mental health overall. On the other hand, those who reported experiencing extreme fear during the ceremony were more likely to experience a range of adverse mental states, and this fear was linked to worse mental health later on. The authors suggest that fear during ceremonies may reflect a lack of psychological safety or inadequate support from facilitators, and that additional preparation and aftercare could reduce these risks.
Interestingly, although women were more likely to report adverse effects in earlier analyses of the same dataset, gender was not associated with worse mental health outcomes in the current study. This finding suggests that women may have protective social factors or coping strategies that buffer against the negative impact of challenging experiences. It also points to the need for more gender-sensitive research on psychedelic use, as most existing studies do not break down outcomes by gender.
“The main takeaway is that many of the so-called ‘adverse effects’ of ayahuasca—especially perceptual changes like visual distortions—may not be inherently harmful and can even be associated with better mental health,” Bouso said. “Experiences of fear or emotional disconnection, especially among individuals with prior mental health issues or in non-traditional contexts, are more likely to correlate with negative outcomes. Context, preparation, and support are key in determining whether these effects lead to growth or distress.”
The researchers emphasize that their study does not establish cause-and-effect relationships. Because the data were self-reported and collected retrospectively, it is possible that people’s memories or interpretations of their experiences were influenced by other factors. The non-random sampling method also limits how generalizable the findings are to all ayahuasca users.
“Our study can’t prove causality,” Bouso said. “The data depend on participants’ memory and subjective interpretation of past experiences, which may be influenced by personal beliefs. The sample is also self-selected and not representative of all ayahuasca users. ”
Nevertheless, the size and diversity of the sample make it one of the most comprehensive analyses to date of how ayahuasca-related experiences relate to mental health.
Regarding the long-term goals for this line of research, Bouso said that “we want to deepen our understanding of how individual vulnerabilities (like previous mental health diagnoses) and non-pharmacological factors (such as ceremony context, guidance, and integration support) shape outcomes. This knowledge is vital for designing harm reduction strategies, informing policy, and eventually creating regulatory frameworks that ensure safety and accessibility while respecting the cultural origins of these practices.”
The study, “A new insight into ayahuasca’s adverse effects: Reanalysis and perspectives on its mediating role in mental health from the Global Ayahuasca Survey (GAS),” was authored by Óscar Andión, José Carlos Bouso, Jerome J. Sarris, Luís Fernando Tófoli, Emérita Satiro Opaleye, and Daniel Perkins.
