A single dose of ayahuasca did not alter the recognition of emotions in facial expressions compared with placebo in healthy volunteers. The drug was well tolerated, producing nausea, gastrointestinal discomfort, and vomiting, with some reports of visual effects, tranquility, and well-being, and few reports of transient anxiety or confusion. No significant effects appeared on cardiovascular measures or brain-derived neurotrophic factor levels. A significant time-dependent deterioration of alkaloids, especially dimethyltryptamine, was observed. The absence of effects on emotion recognition may stem from the dose used, alkaloid degradation, learning effects, or the sample's high educational level.
In a small preliminary trial, ayahuasca—with or without a 600 mg dose of cannabidiol (CBD) given 90 minutes beforehand—did not produce interactive effects on emotion recognition or empathy tasks. Both groups showed faster reaction times on these tasks and reported reduced anxiety, sedation, and discomfort, but there were no differences between the group that received CBD and the one that did not. Ayahuasca was well tolerated, causing mainly nausea and gastrointestinal discomfort, with no clinically significant changes in heart or liver measures. The safety of the combination suggests that both drugs could be tested in larger trials for anxiety disorders.