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CompletedNCT07910838Updated Nov 2, 2026

Single-dose Effects of Ayahuasca Compared to Esketamine on Experimentally Induced Pain

An Early Phase 1 interventional study of Ayahuasca and Esketamine 0.2 mg/kg in Healthy Adult Participants, sponsored by University of Sao Paulo. Completed at 1 site in Brazil. Open to participants aged 18 Years to 50 Years, including healthy volunteers. Per ClinicalTrials.gov, last updated 2026-11-02.

Sponsored by University of Sao Paulo · Early Phase 1, Interventional, and Other

From the registry’s dates

  • Registered 3 years 4 months after the study started (first participant enrolled Jun 2023, registered Oct 2026).
Updated Nov 2, 2026Newly registeredGo to Updates ↓
Phase
Early Phase 1
Study type
Interventional
Enrollment
20
Allocation
Randomized
Ages
18 Years to 50 Years
Sex
All
01

Study summary

This was a randomized, parallel, double-blind clinical trial with healthy volunteers

02

Conditions studied

  • Healthy Adult Participants
03

In context

Lead sponsor

University of Sao Paulo is the lead sponsor of 1,035 studies on the registry; 95 are open to participants now.

Of its 8 completed or terminated interventional studies of FDA-regulated products, 0 (0%) have results posted.

Browse University of Sao Paulo studies →

Counted across the registry records on this site, refreshed daily.

04

Who can participate

Ages eligible
18 Years to 50 Years
Sexes eligible
All
Accepts healthy volunteers
Yes

Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.

Inclusion criteria

- healthy volunteers

Exclusion criteria

Exclusion Criteria:

  • included history of cardiovascular, liver, or neurological diseases;
  • pain disorders and/or reports of chronic or acute pain (self-reported);
  • a score >10 on the Patient Health Questionnaire (PHQ-9) and Generalized Anxiety Disorder-7 (GAD-7) scales;
  • any psychiatric diagnosis evaluated through the International Neuropsychiatric Interview (M.I.N.I; );
  • pregnant or breastfeeding women;
  • previous experience (> 2 lifetime uses) with ayahuasca;
  • use of psychoactive medications (antidepressants, mood stabilizers, anxiolytics, and antipsychotics);
  • use of other drugs (psychostimulants, maximum of 20 lifetime uses; hallucinogens, maximum of 10 lifetime uses).
  • In addition, participants could not have experienced any kind of pain in the last seven days, as identified through a pre-existing pain condition checklist questionnaire. -
Terms in these criteria, in plain language(1)

Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.

DSM diagnostic criteria

The American Psychiatric Association’s manual of mental health diagnoses. DSM-5 (2013, revised as DSM-5-TR in 2022) replaced DSM-IV, and some studies still name the older edition. “Meets DSM criteria for …” means diagnosed by that edition’s diagnostic criteria, usually by a clinician in an interview.

05

Study design

Phase
Early Phase 1
Primary purpose
Other
Allocation
Randomized
Intervention model
Parallel assignment
Masking
Double (Participant, Investigator)
Enrollment
20 participants (actual)

Study arms

  • Experimental
    Ayahuasca

    experimental

    Drug: Ayahuasca

  • Active comparator
    esketamine

    Drug: Esketamine 0.2 mg/kg

Interventions

06

What researchers measure

Primary outcomes

  1. Subjective pain

    Pain intensity measured with a visual analogue scale (pain visual analogue scale with scores ranging from 0 to 10, where higher scores mean more pain)

    Time frame: 0 to 4 hours post-drug

  2. Pain tolerance

    Pain tolerance measured in Celcius

    Time frame: 0 to 4 hours

07

Study locations

1 site
  • Hospital das Clínicas da FMRP-USP
    Ribeirão Preto, São Paulo 1421360, Brazil
08

Timeline

1 registry update since Sep 25, 2026
ElapsedEstimatedEstimated, not yet reached

Ran from Jun 2023 to primary completion in Jul 2025, 25 months.

How these figures are worked out, and which studies are left out of them.

Registered
Oct 14, 2026
First posted
Nov 2, 2026
StartActual
Jun 1, 2023
Primary completionActual
Jul 30, 2025
CompletionActual
Jul 30, 2025
Last update
Nov 2, 2026
What these dates mean
Start.
When the first participant enrolled; while estimated, when the study expects to open to recruitment.
Primary completion.
When the last participant was examined or treated to collect data for the study's main question, its primary outcome. A study that stopped early gives the date its data collection stopped.
Completion.
When the last participant's last visit took place, for every outcome, secondary ones and side effects included: the end of the study. Often later than primary completion, sometimes the same day.
Actual and Est.
Actual means the registry says the date has happened. Est. (estimated) is a date the sponsor plans or expects. It can still move, and the sponsor is expected to change it to actual once it has passed.
Registered
First appeared on the registry. No changes since
Nov 2, 2026
Show all 1 update
  1. Nov 2, 2026
    First appeared on the registry

From the registry record's own update history. This site started tracking changes on Sep 25, 2026; for anything earlier, see the record history on ClinicalTrials.gov ↗

09

Registry details

Key details

Study ID
NCT07910838
Lead sponsor
University of Sao Paulo
Responsible party
Rafael Guimarães dos Santos (Associate Professor, University of Sao Paulo) — Principal investigator
First posted
Nov 2, 2026
Start date
Jun 1, 2023
Primary completion
Jul 30, 2025
Completion
Jul 30, 2025
Last update
Nov 2, 2026

Oversight

Data monitoring committee
No
FDA-regulated drug
No
FDA-regulated device
No
View the source record on ClinicalTrials.gov ↗

Not currently enrolling

This study is completed, as verified in Oct 2026. You cannot join it, but the record below documents what was studied.

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Discussion

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