Clinical TrialAyahuascaPlaceboCompleted

Ayahuasca vs. Placebo for Social Anxiety Disorder: A Randomized, Double-Blind, Placebo-Controlled Pilot

Randomized, double-blind, placebo-controlled, parallel-group pilot (University of São Paulo, Brazil; conducted September 2015 – July 2019) of a single oral dose of ayahuasca (2 mL/kg; prepared by a Santo Daime church and stored refrigerated; alkaloid concentrations verified by UPLC-MS) versus placebo (2 mL/kg; mineral water, glycerin, propylene glycol, methylparaben; organoleptic match) in 17 undergraduate volunteers (15 women) meeting DSM-5 Social Anxiety Disorder criteria confirmed by SCID-5-CV (SPIN ≥19 or excessive social fear on screening). From 894 screened, 17 met criteria and were randomised: 9 to ayahuasca, 8 to placebo. Key exclusions: current SAD treatment, major medical or other psychiatric disorders (except comorbid anxiety), psychoactive medications, recurrent illicit drug use, prior ayahuasca use (>2 lifetime hallucinogen uses), pregnancy/lactation. Primary outcome: Self-Statements During Public Speaking Scale (SSPS) state version during a Simulated Public Speaking Test (SPST; anticipatory, preparation and speech phases) administered 300–355 minutes post-dose. Secondary outcomes: Visual Analogue Mood Scale (VAMS; anxiety, sedation, cognitive impairment, discomfort factors) at 11 time points from baseline to 355 minutes; Bodily Symptoms Scale (BSS); Beck Anxiety Inventory (BAI; baseline, 240 min, follow-ups); Recognition of Emotions in Facial Expressions (REFE) task; cardiovascular measures. Follow-up at days 7, 14, and 21. Analysis: two-way repeated-measures ANOVA (time × group), Bonferroni correction, α=0.05, η² effect sizes. No formal sample size calculation (pilot feasibility study). All 17 completed the experimental session and three follow-ups; equipment failure reduced some outcome analyses to 14 participants (7 per group). No trial registry number reported.

Target Enrollment
17 participants
Study Type
Phase II interventional
Design
Randomized, double Blind

Study Arms & Interventions

Ayahuasca

experimental

Single dose of ayahuasca administered in a 200 mL brownish/opaque glass bottle.

Interventions

  • Ayahuasca2 mL/kg
    via oral• single dose• 1 doses total

    The dose was chosen based on previous work to elicit psychotropic effects. The batch contained DMT, harmine, THH, and harmaline.

Placebo

placebo

Nonpsychoactive substance with similar organoleptic properties (color, taste, smell) to ayahuasca, administered in a 200 mL brownish/opaque glass bottle.

Interventions

  • Placebo2 mL/kg
    via oral• single dose• 1 doses total

    Prepared with mineral water (500 mL), glycerin 5%, propylene glycol 5%, and methylparaben 0.1% to mimic the nauseous and bitter taste of ayahuasca.

Primary Results(1 publication)

Participants

N = 17Mean age: 24.9 across armsG. et al. 2021 →

SSPS

Score at Timepoint

Ayahuasca35 (±5.292) [31.08, 38.92]Day 0.221·G. et al. 2021 →
Placebo25 (±5.292) [21.08, 28.92]Day 0.221·G. et al. 2021 →

Adverse Events (from all publications)

Arm / GroupnAny TEAESevereSeriousDiscont.
Ayahuascaexperimental917(188.9%)—0(0.0%)0(0.0%)
Placeboplacebo80(0.0%)—0(0.0%)0(0.0%)

* The text reports specific counts for adverse effects: gastrointestinal discomfort and nausea (n=4), vomiting (n=3), drowsiness (n=2), confusion (n=2), headache (n=2), diarrhea (n=1), fear (n=1), distress (n=1), and dissociation/depersonalization (n=1). Summing these unique reported effects/participants is not explicitly provided as a single 'teaeAny_n' total, but the text states 'no serious adverse events or dropouts were observed'. Note: The analysis was performed on 14 volunteers (7 per group) due to equipment issues, but the safety/tolerability section describes the full group of 17 volunteers.

* The text explicitly states: 'In the placebo group, no adverse events were reported.'

Study Details

  • Status
    Completed
  • Phase
    Phase II
  • Type
    interventional
  • Design
    Randomizeddouble Blind
  • Target Enrollment17 participants
  • Timeline
    Start: 2015-09-01
    End: 2019-07-01
  • Compounds
    AyahuascaPlacebo

Related Publications

Ayahuasca Improves Self-perception of Speech Performance in Subjects With Social Anxiety Disorder: A Pilot, Proof-of-Concept, Randomized, Placebo-Controlled Trial

Published
Authors
Dos Santos, R. G., Osório, F. L., Rocha, J. M., Rossi, G. N., Bouso, J. C., Rodrigues, L. S., Silveira, G., Yonamine, M., Hallak, J. E.

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