Direct Comparison of Altered States of Consciousness Induced by LSD, Psilocybin, and DMT in Healthy Participants (LPD)

This randomised, placebo-controlled, triple-blind Phase I crossover trial (n=24) will compare the acute and subacute effects of LSD (150µg), psilocybin (30mg), and DMT (up to 2 mg/min intravenous infusion) in healthy adults, with all sessions standardised using ketanserin (20 mg IV) to end the psychedelic experience after three hours.

Conducted by University Hospital Basel in Switzerland, this trial is designed to determine whether these three classic psychedelics produce qualitatively similar altered states of consciousness when effect duration is controlled. Previous comparative studies have struggled with blinding due to differing drug durations. This study aims to overcome that by administering ketanserin—a 5-HT2A receptor blocker—midway through each session to uniformly end the effects of all substances.

Participants will undergo four sessions (LSD, psilocybin, DMT, and placebo) in random order, with extensive physiological and psychological measurements taken during and after each dose. These include questionnaires assessing altered states of consciousness, mystical-type experiences, emotional breakthroughs, and blood sampling for hormone and drug plasma levels. The study will help clarify the similarities and differences in subjective and biological effects between these commonly studied psychedelics, while also evaluating the feasibility of using DMT in longer, therapeutically structured sessions.

Topic Healthy Subjects
Compound LSD Psilocybin DMT Placebo
Country Switzerland
Visit trial
Status Recruiting
Results Published No
Start date 01 April 2025
End date 01 August 2026
Phase Phase I
Design Blinded
Type Interventional
Generation First
Participants 24
Sex All
Age 25- 99
Therapy No

Trial Details

The primary objective of this study is to determine whether equivalent moderately high doses of LSD, psilocybin, and DMT produce qualitatively similar peak effects when the effect duration is standardized with ketanserin. A DMT infusion mimicking oral LSD and psilocybin administrations will be tested, as well as intravenously administered ketanserin.

Trial Number NCT06899334

Sponsors & Collaborators

University of Basel
The University of Basel Department of Biomedicine hosts the Liechti Lab research group, headed by Matthias Liechti.

Data attribution

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