Acute Effects of Different Psychedelics and Their Interaction with Other Medications

Acute Effects of Different Psychedelics and Their Interaction with Other Medications

by Prof. Dr. med. Matthias Liechti

Life & Natural Systems Medicine & Health MKGPharmacologyMKGWPsychopharmacology
🎙 Prof. Dr. med. Matthias Liechti 👥 7K 📅 August 24, 2025 ⏱ 28 min 👁 139 📄 expert opinion 🧭 2026-08-16
Available in: English (current) Français

Keywords

LSDpsilocybinMDMASSRIdrug interactions

Summary

In this talk from the INSIGHT 2023 conference, Prof. Matthias Liechti presents findings from controlled studies at the University Hospital of Basel on the acute dose-dependent effects of psychedelics (LSD, psilocybin, MDMA, mescaline, DMT) in healthy subjects. He emphasizes that positive acute subjective effects (e.g., oceanic boundlessness, mystical experiences) predict better therapeutic outcomes in depression and anxiety, while anxiety-inducing experiences do not. He discusses dose equivalences (e.g., 100 µg LSD ≈ 20 mg psilocybin ≈ 500 mg mescaline) and notes that LSD has a longer duration than psilocybin. Regarding drug interactions, he reports that SSRIs do not reduce the positive effects of psilocybin but may reduce anxiety, and thus recommends continuing SSRIs during psilocybin therapy. For LSD, he advises caution with CYP2D6 poor metabolizers and potential dose reduction. For MDMA, SSRIs reduce its subjective effects, so pausing them is recommended. He also discusses pharmacogenetics (CYP2D6) affecting LSD and MDMA kinetics, and notes that MDMA’s effects last only ~6 hours despite a long half-life, questioning the need for booster doses. He concludes with practical dosing recommendations and highlights the Swiss program treating ~500 patients with psychedelics.

185 words

Critical Evaluation

Value of the Information & Strength of the Argument

The talk provides high-value information from rigorous controlled studies, offering evidence-based dosing guidelines and interaction data. The argumentation is solid, based on quantitative data and clinical observations, with clear explanations of pharmacological mechanisms. The speaker acknowledges limitations and distinguishes between evidence-based and anecdotal recommendations, enhancing credibility.

Scientific Rigor, Source Quality, Title Accuracy

The scientific rigor is high, with references to controlled studies and clinical programs. The speaker cites specific studies (e.g., by Roland Griffiths, Robin Carhart-Harris) and mentions the Swiss program. The title accurately reflects the content. No comments were provided, so no analysis of public trends is included.

108 words

Title / Content Match

The title accurately reflects the content, focusing on acute effects and drug interactions of psychedelics.

Quality & Reliability

9/10

Presentation by a leading clinical pharmacologist with extensive controlled studies; data from peer-reviewed research and clinical programs; transparent about limitations and anecdotal evidence.

Key Moments

Markers derived by PSI from the transcript: the creator did not define chapters.

Cited Sources

Concurring Sources

Contribution & Novelties

The talk provides a comprehensive synthesis of acute effects and interactions of psychedelics, with practical dosing recommendations based on controlled studies. It highlights the importance of positive subjective experiences for therapeutic outcomes and offers evidence-based guidance on managing SSRIs and other medications.

Pour aller plus loin :

70 words

Radar Profile

The profile shows high scores across all dimensions, indicating a well-balanced and reliable presentation with substantial information, strong scientific quality, and appropriate technical depth.

Reliability 9/10