What counts as a psychedelic?
Psychedelics have long captured human interest, inspired spiritual exploration, and prompted scientific inquiry. But the question “What counts as a psychedelic?” is not as straightforward as it might seem. In casual conversation, we might call something a psychedelic if it creates colorful visual distortions, shifts in perception, or even mystical experiences. In a more technical sense, many researchers rely on specific pharmacological criteria (often tied to receptor binding) to determine which substances qualify as psychedelics. Here, we will explore two common ways of classifying and discussing psychedelics: one centered on chemical interactions in the brain, the other oriented toward the subjective experiences they produce.
1. By Pharmacological Action: 5-HT2A Receptor Agonists
One of the leading scientific frameworks for classifying “classic” psychedelics is their effect on serotonin 5-HT2A receptors in the brain. These receptors, part of the larger serotonin receptor family, are key to regulating mood, cognition, and perception. Substances that bind to (or “agonize”) these 5-HT2A receptors are widely recognized as producing what we typically understand to be a “psychedelic” experience.
LSD (Lysergic Acid Diethylamide): Often referenced in discussions of psychedelics, LSD is a potent 5-HT2A agonist. It is known for intensifying sensory input, altering thought patterns, and creating vivid visual effects.
Psilocybin (Found in ‘Magic Mushrooms’): Psilocybin is converted in the body to psilocin, which interacts strongly with 5-HT2A receptors. Users commonly report perceptual changes, emotional introspection, and altered sense of time.
DMT (Dimethyltryptamine): Found naturally in some plant species, DMT is also a strong 5-HT2A agonist and is known for producing extremely intense, short-lived visionary states.
Mescaline (Found in Peyote & San Pedro Cacti): Although chemically different from LSD and psilocybin, mescaline also acts on 5-HT2A receptors, leading to visual changes, shifts in bodily sensation, and—in many cases—feelings of euphoria.
These examples help highlight why many scientists rely on the 5-HT2A classification to define psychedelics: in all these cases, the substance primarily activates the same receptor subtype, shaping a range of perceptual and cognitive effects that are similar enough to fit under a single banner.
2. By the Nature of the Experience: Subjective Effects
Another way to approach the definition of psychedelics is to focus on the experiences they induce rather than on their pharmacological mechanisms alone. From this vantage point, any substance or practice that brings about significant alterations in perception, cognition, or consciousness might be considered “psychedelic.” This broader perspective sometimes includes not only classic serotonergic compounds but also other substances and experiences known for inducing altered states of consciousness.
a) Sensory and Visual Changes
Psychedelics are often identified by their signature sensory effects: vibrant colors, wave-like visual distortions, or synesthesia (where senses overlap, such as “seeing” sounds). Within this category, anything that causes profound shifts in how we see, hear, or feel the world could be considered psychedelic.
b) Mystical and Spiritual Dimensions
Many people who use psychedelics describe transcendental or mystical experiences: a sense of unity, ego dissolution, or profound insight. Substances as varied as LSD, ayahuasca (a DMT-containing brew), and even certain breathwork practices can bring about a sense of spiritual awakening or cosmic perspective. From this point of view, “psychedelic” means more than just chemical action—it indicates a doorway to deeper introspection or perceived higher awareness.
c) Emotional and Psychological Exploration
Psychedelics can also facilitate deep emotional introspection. Therapy models that incorporate psychedelics (under regulated conditions) often emphasize how these substances may allow individuals to revisit unresolved traumas, reframe self-limiting beliefs, or forge better connections to inner states. While this might still relate to the 5-HT2A receptor, the classification here centers on the therapeutic and transformative experience.
3. Where the Lines Blur
Although the 5-HT2A receptor agonist concept helps form a neat category of “classic” psychedelics, the lines can blur when we look at real-world use and subjective experiences. Some substances might not be classical psychedelics in the pharmacological sense but still induce effects that people describe as “psychedelic.” For instance:
Dissociatives like ketamine act primarily on NMDA receptors. While they are typically classified outside the “classic” psychedelic category, they produce strong alterations in perception and cognition that some might call “psychedelic” in a looser sense.
Empathogens like MDMA (Ecstasy) increase serotonin levels but interact with different receptor mechanisms and are primarily associated with feelings of empathy and emotional warmth. Some might include them in the “psychedelic” sphere, while others argue they are more properly termed “entactogens.”
4. Why Definitions Matter
Defining “psychedelic” has more than academic significance—it shapes public policy, guides scientific research, and informs therapeutic approaches. Understanding whether a substance has potential benefits for treating depression, anxiety, or PTSD often hinges on consensus around definitions, because that influences how clinical trials are structured and how results are interpreted.
Policy and Regulation: Governments use classification systems to regulate drugs. Strict definitions can either hinder or facilitate research based on how a substance is scheduled.
Medical and Therapeutic Research: The expanding field of psychedelic-assisted therapy relies on precise definitions for integrating these substances into clinical settings. Understanding that LSD and psilocybin are both “classic psychedelics” means researchers can build on each other’s work and compare results more meaningfully.
Cultural and Social Context: In popular culture, the term “psychedelic” often carries a set of associations tied to creativity, counterculture, or spiritual exploration. Being aware of the technical definitions can help clarify what we mean when we use that term.
Conclusion
Whether we define psychedelics primarily through their pharmacological action at 5-HT2A receptors or by the experiential states they evoke, the concept of “what counts as a psychedelic” can be approached in multiple ways. For some, it’s a strict, receptor-based definition that includes LSD, psilocybin, DMT, and mescaline at its core. For others, it’s an expansive notion of any substance or practice that triggers altered states of consciousness, potentially including dissociatives or empathogens.
In the end, both definitions have their merits. Pharmacological classification provides clarity for scientific study and medical applications, while focusing on the subjective experience highlights the profound and diverse ways that human consciousness can be altered. Understanding both perspectives allows for a richer dialogue—one that can pave the way for better research, improved therapeutic tools, and a deeper appreciation of the intricate interplay between mind, brain, and the many ways we alter our perceptions.