An entheogen is a psychoactive substance used specifically to induce spiritual or mystical experiences, typically within a religious, ceremonial, or shamanic context. The term was coined in 1979 by a group of scholars including Carl Ruck, Jonathan Ott, and R. Gordon Wasson to replace words like “hallucinogen” and “psychedelic,” which they felt carried too much cultural baggage from the 1960s counterculture. Built from Greek roots meaning roughly “generating the divine within,” the word emphasizes the sacred intent behind using these substances rather than their chemical effects alone.
How “Entheogen” Differs From “Psychedelic”
The word “psychedelic,” coined in 1957, translates loosely to “mind-manifesting.” It describes what these substances do to your perception: they reveal or amplify mental content. “Entheogen” reframes the same experience through a spiritual lens, highlighting encounters with what users describe as internal or external spiritual entities, feelings of oneness, or a sense of direct contact with the sacred. The chemistry is often identical. Psilocybin mushrooms are a psychedelic in a clinical trial and an entheogen in an Indigenous ceremony. The distinction lives in the intention and context surrounding use, not in the molecule itself.
This isn’t just semantic hairsplitting. The framing shapes how people prepare for and interpret the experience. Researchers studying these substances increasingly recognize that personal mindset and social environment profoundly influence outcomes, which is one reason the ceremonial framework around entheogens has persisted for thousands of years.
Plants and Substances Classified as Entheogens
Most entheogens come from plants or fungi, though a few come from animal sources. The major categories include:
- Psilocybin mushrooms (known to the Aztec as teonanácatl, meaning “flesh of the gods”): contain psilocybin, which your body converts into psilocin, the compound that actually produces psychoactive effects. A typical experience lasts four to six hours.
- Peyote (Lophophora williamsii): a small cactus native to Mexico and the southwestern United States, used for its mescaline content. Related cacti in the Trichocereus family, such as San Pedro, also contain mescaline.
- Ayahuasca: a brew made from two Amazonian plants. One (Banisteriopsis caapi) contains compounds that prevent your gut from breaking down DMT, the hallucinogenic ingredient supplied by the second plant (Psychotria viridis). Neither plant works the same way alone.
- Morning glory seeds (Turbina corymbosa, known in Mesoamerica as ololiuhqui): contain ergine, a compound structurally related to LSD but much milder.
- Salvia divinorum: a mint-family plant from Oaxaca, Mexico, with an unusual mechanism of action distinct from most other entheogens.
- Toad secretions: the skin of certain Bufo species contains psychoactive compounds. Archaeological evidence shows Olmec cultures used these substances over 3,000 years ago.
Less commonly grouped under the entheogen label are ibogaine (from the West African iboga shrub), cannabis in certain Rastafari and Hindu traditions, and even tobacco when used ceremonially by Indigenous peoples of the Americas. The wild tobacco species Nicotiana rustica, far stronger than commercial tobacco, was one of many plants used for its psychoactive properties across Mesoamerica.
Thousands of Years of Ceremonial Use
Entheogen use is not a modern phenomenon. In pre-Columbian Mesoamerica, the Olmec, Zapotec, Maya, and Aztec civilizations all incorporated psychoactive plants into healing rituals and religious ceremonies. The Maya drank balché, a fermented mixture of honey and plant extracts, in group ceremonies. The Aztec consumed psilocybin mushrooms and morning glory seeds in carefully structured rituals overseen by spiritual specialists. Jimson weed, water lily, and wild tobacco rounded out a pharmacopoeia that spanned centuries and multiple civilizations.
These weren’t casual or recreational practices. Access to entheogens was typically controlled by shamans, priests, or healers who managed dosing, guided the experience, and interpreted its meaning. That structure served a function similar to what modern researchers now call “set and setting,” the combination of psychological preparation and physical environment that shapes how a psychedelic experience unfolds.
How Entheogens Affect the Brain
Most classical entheogens, including psilocybin, DMT, and mescaline, work primarily by activating a specific type of serotonin receptor in the brain. This activation increases the excitability of neurons in the outer layers of the cortex, which is why these substances produce such vivid changes in perception, emotion, and sense of self.
One of the most consistent findings from brain imaging studies is that these substances disrupt something called the default mode network, a group of interconnected brain regions that are most active when you’re not focused on any particular task. This network handles things like daydreaming, self-reflection, and maintaining your sense of personal identity over time. Under the influence of psilocybin or similar substances, the usual communication patterns within this network break down while connections between brain regions that don’t normally talk to each other increase dramatically.
This rewiring may explain the characteristic features of entheogenic experiences: the dissolution of ego boundaries, the sense that time has stopped, feelings of unity with something larger than yourself. People having a positive experience typically report euphoria, connectedness, and a feeling of deep meaning. Those having a difficult experience can feel intense fear, anxiety, and distress. Long-term ayahuasca use has even been associated with measurable physical changes in brain structure, with certain regions growing thicker and others thinner over time.
Clinical Research on Entheogenic Substances
The spiritual framing of entheogens has historically kept them at arm’s length from Western medicine, but that gap is narrowing. Clinical trials are now investigating several of these substances for serious mental health conditions.
One of the most striking results comes from research on ibogaine, a psychoactive compound derived from an African shrub long used in Bwiti spiritual traditions. In a Stanford Medicine study of 30 military veterans with traumatic brain injuries, participants saw their disability scores drop from 30.2 (mild to moderate disability) to 5.1 (no disability) one month after treatment. PTSD symptoms dropped by 88%, depression symptoms by 87%, and anxiety symptoms by 81%. Most of the participants had also met criteria for PTSD, anxiety disorders, or alcohol use disorder at the start of the study.
Psilocybin has shown promising results in trials for treatment-resistant depression, end-of-life anxiety in cancer patients, and addiction. These clinical protocols deliberately incorporate elements that resemble traditional entheogenic practice: careful preparation, a guided experience in a comfortable environment, and structured follow-up sessions to help participants integrate what they experienced.
Safety Risks and Interactions
Entheogens are pharmacologically active substances with real risks, particularly for people with certain pre-existing conditions. Because these compounds act on the serotonin system, they can interact dangerously with common psychiatric medications, including SSRIs, SNRIs, tricyclic antidepressants, and MAO inhibitors. Some of these combinations raise the risk of serotonin toxicity, a potentially life-threatening condition where excess serotonin causes rapid heart rate, high blood pressure, muscle rigidity, and seizures.
Cardiovascular safety is another concern that researchers are still working to understand. The current evidence on psychedelic safety was largely gathered from healthy volunteers, and it does not necessarily extend to people with heart conditions. Psilocybin in particular strongly activates a serotonin receptor subtype associated with heart valve changes, which raises questions about the safety of repeated low-dose (“microdose”) use over long periods.
Psychological risks are equally important. While the physiological toxicity of most classical entheogens is relatively low compared to many common drugs, the intensity of the experience itself can be destabilizing, especially for individuals with a personal or family history of psychotic disorders. This is one reason traditional cultures surrounded these substances with elaborate preparation, experienced guides, and specific ritual contexts rather than treating them as something to be consumed casually.