Psychiatry experts call for an end to placebo-controlled clinical trials in psychedelic therapies, arguing they lack validity, pose ethical risks, and fail to reflect clinical realities
Rethinking placebos in psychedelic therapies for psychiatric illness
A growing number of psychiatrists and researchers are urging a reconsideration of placebo-controlled trials in the field of psychedelic-assisted therapies. In a recent letter published in The British Journal of Psychiatry (July 2025), Amy Lehrner and colleagues argue that clinging to outdated models of clinical trials is not only scientifically imprecise but ethically problematic when it comes to psychedelic treatments. Here’s why traditional placebo designs are falling short—and what alternatives could provide more rigorous, meaningful data for both science and patient care.
Why the placebo model is breaking down in psychedelic research
For decades, randomized placebo-controlled trials (RCTs) have been considered the gold standard in medicine. However, when it comes to psychedelic-assisted psychotherapy, this methodology is reaching its limits—not because researchers are less rigorous, but because the nature of the treatment itself has radically changed.
One of the core problems is that there is no realistic placebo for psychedelics. Substances like psilocybin, LSD or MDMA induce profound, unmistakable effects on perception, mood, and consciousness. This makes it nearly impossible to maintain the “blinding” of clinical trials—meaning neither participants nor therapists can remain unaware of who received the active substance and who didn’t. This undermines the internal validity of such studies, rendering their conclusions questionable.
Even when so-called active placebos are used—such as low doses of psychedelics or mild stimulants—they typically fail to replicate the experiential impact of the full dose. Participants can usually guess correctly what group they are in, which creates expectation bias. And if psychotherapy is involved—which it almost always is in these treatments—the problem is doubled. You can’t simulate therapy without offering some therapeutic interaction. So placebo groups end up receiving a different type and quality of care.
A complex treatment that can’t be isolated in a Petri dish
Psychedelic-assisted therapies are more than just pharmacological interventions; they are complex, synergistic processes that unfold within a psychological, relational, and environmental framework. This is especially true in MDMA-assisted therapy for PTSD, and implicitly so in psilocybin trials, where the drug is accompanied by intensive psychological support.
Attempting to dissect this integrated treatment into separate components—drug versus context—misses the point. Even advocates of placebo-controlled trials admit that the “active component” may be an emergent property of a complex system involving the drug, therapeutic alliance, set and setting, and patient expectations. Studying psychedelics as if they were SSRIs or traditional antidepressants misrepresents what these treatments are and how they work. The result? Misleading or incomplete conclusions that fail to reflect real-world therapeutic dynamics.
Ethical issues beyond methodology
Beyond methodological limitations, placebo-controlled psychedelic trials raise serious ethical concerns. Assigning patients with severe psychiatric disorders to placebo groups may exacerbate their suffering—especially when alternative or promising treatments exist. This challenges the principle of clinical equipoise, which holds that no participant in a study should knowingly receive inferior care without strong justification.
Many of the patients in psychedelic studies are people who have exhausted existing options and are desperate for relief. Excluding them from potentially beneficial treatments, or misleading them into thinking they may receive them, isn’t just scientifically questionable—it’s clinically unjust.
Moreover, exposing participants to intense preparation for a psychedelic session, only to give them an inactive placebo, can cause emotional harm. In such cases, the patient undergoes the stress and expectation of a transformative experience without the therapeutic effect, which can worsen symptoms like hopelessness and anxiety.
Regulatory agencies in other fields—such as oncology—have recognized these issues and now recommend alternative trial designs when blinding is unfeasible or unethical. It’s time to apply that same logic to psychiatric research involving psychedelics.
Alternatives to the placebo: rigorous and realistic
Criticizing placebo-based designs doesn’t mean abandoning scientific rigor. On the contrary, researchers are calling for more innovative, clinically relevant methodologies that better match the nature of psychedelic treatments. Here are some of the most promising alternatives:
Active comparator trials
Instead of comparing psychedelics to an inert placebo, compare them to standard treatments. For example, assess psilocybin-assisted therapy against conventional antidepressants plus psychotherapy. This allows researchers to answer real-world questions: Is the psychedelic approach more effective, or at least non-inferior? These trials yield data that is more meaningful for patients, clinicians, and policymakers alike.
Adaptive trial designs
Adaptive designs allow researchers to make adjustments during the trial—such as modifying dose, frequency, or dropout criteria—based on interim data. This increases efficiency, personalizes treatment, and minimizes risk. These designs are already widely used in oncology and cardiovascular medicine.
Embracing expectancy as a variable
Instead of treating expectation as statistical noise, incorporate it as a meaningful variable. For instance, some participants could be primed to expect greater benefits, while others receive neutral messaging. This helps researchers understand how expectancy moderates therapeutic outcomes, and how best to integrate it into clinical protocols.
Bayesian models and historical controls
Bayesian methodologies use existing data to supplement or even replace control groups, reducing the need for large placebo arms. For example, if previous open-label studies consistently show positive outcomes, those can serve as a benchmark. Similarly, benchmarking studies can set predefined thresholds of improvement or side effects based on historical data.
Pragmatic clinical trials
Unlike explanatory trials with narrow inclusion criteria and artificial settings, pragmatic trials test treatments in real-world conditions. This means including diverse patients and using routine clinical environments, producing results that are more generalizable and useful for health systems.
Registries, platform trials and machine learning
Finally, registry-based studies and master protocols offer flexible, scalable frameworks for evaluating psychedelic therapies. Researchers can track large cohorts, compare multiple interventions, and use machine learning to detect patterns or personalize treatments. Digital health tools, wearables, and mobile apps can provide continuous, objective data that enrich our understanding beyond what a traditional trial can offer.
A new paradigm for 21st-century therapies
The debate over placebos in psychedelic research reflects a deeper tension between tradition and innovation in clinical science. On the one hand, randomized placebo-controlled trials have served us well. On the other, we now face a new class of treatments that defy the assumptions underpinning those methods.
As Lehrner and colleagues argue, clinging to placebo designs in this context is “a doomed attempt to reduce a complex treatment and mislabel that reduction as rigor.” Worse, it risks generating irrelevant data while delaying the translation of effective therapies into clinical practice.
If we want to know whether psychedelic-assisted therapies are safe, effective, and suitable for public health systems, we need to update our tools. Funders, regulators, and scientists must stop chaining the future of psychedelic research to obsolete frameworks and embrace alternative methodologies that maintain scientific integrity while enhancing ethical and ecological validity.
Ultimately, the path forward is not less rigorous—but more intelligently rigorous. Real scientific progress will come not from blinding ourselves to complexity, but from looking it squarely in the face and learning how to study it properly.
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Raúl del Pino is a prominent psychonaut, writer, and authority on psychoactive substances, particularly psychedelics.
He founded www.psiconautica.org in 1996, the first Spanish-language website dedicated to drugs, focusing on Altered States of Consciousness and Transpersonal Psychology. He is the author of the books Contemporary Guide to the Psychedelic Journey and MDMA, Sex, and Tantra. Raúl combines scientific rigor with personal introspection, exploring the relationship between psychoactives, sexuality, and spiritual practices. His work makes a significant contribution to the understanding and responsible use of psychoactive substances.