Mescaline is a naturally occurring psychoactive compound belonging to the phenethylamine class of alkaloids. It is structurally distinct from other common psychedelics like psilocybin and LSD, which are tryptamines. Archaeological evidence suggests its consumption in traditional ceremonies dates back over 6,000 years. This history points to its profound cultural and spiritual significance for indigenous peoples in the Americas, who incorporated mescaline-containing plants into their religious and healing practices.
Natural and Synthetic Origins
Mescaline is biosynthesized naturally within several species of cacti, which serve as the traditional sources for the compound. The most well-known natural source is the slow-growing Peyote cactus, Lophophora williamsii, native to the Chihuahuan Desert of southern Texas and northern Mexico. The mescaline concentration in the dried crown, or “button,” of Peyote is relatively high, typically ranging between 1.8% to 5.5% of the dry weight of the plant tissue.
Another significant natural source is the San Pedro cactus, Echinopsis pachanoi, which is a fast-growing columnar species found in the Andes Mountains. The mescaline content in San Pedro is generally lower than in Peyote, though it contains a wider range of other psychoactive alkaloids. Traditional harvesting of Peyote involves cutting the crown above the root, allowing the plant to regrow, while San Pedro is typically consumed by boiling slices of the stem into a liquid or tea.
Mescaline was the first psychedelic substance to be chemically synthesized in a laboratory setting, first achieved in 1919 by Austrian chemist Ernst Späth. Synthetic mescaline is a white crystalline powder often produced illicitly through various chemical pathways.
Subjective and Physiological Effects
Mescaline exerts its psychoactive effects primarily by acting as an agonist on the serotonin 5-HT2A receptor in the brain. This receptor activation is thought to be the main mechanism responsible for the altered states of consciousness induced by classic psychedelics. Mescaline also binds to a variety of other receptors, including other serotonin receptor subtypes and noradrenaline and dopamine receptors, which may contribute to its distinct profile of effects.
The subjective experience from a moderate oral dose of synthetic mescaline (around 300 to 500 mg) typically begins with an onset period of 45 minutes to over an hour, with peak effects occurring between two and four hours after ingestion. The duration of the full psychedelic experience is notably long compared to other classic psychedelics, often lasting between 8 and 14 hours. The experience is characterized by profound alterations in perception, emotion, and thought.
Users frequently report vivid visual phenomena, which may include intense, intricate, and geometric patterns, both with eyes open and closed. These visual effects are often accompanied by synesthesia, a crossing of sensory modalities where sounds may be “seen” or colors “heard.” Emotional responses can vary widely, often including feelings of euphoria, deep introspection, and a sense of transcendence. Challenging experiences involving anxiety or paranoia, sometimes referred to as a “bad trip,” can also occur.
Physiological responses to mescaline are common, particularly in the initial phase of the experience. The ingestion of mescaline-containing cactus material is frequently associated with pronounced nausea and vomiting. Mescaline also stimulates the sympathetic nervous system, causing measurable changes such as an increase in heart rate, elevated blood pressure, and pupil dilation. Nausea and vomiting tend to be more frequent with the consumption of the raw cactus material compared to pure synthetic mescaline.
Current Regulatory Landscape
In the United States, mescaline is classified federally as a Schedule I controlled substance under the Controlled Substances Act (CSA). This classification signifies the substance has a high potential for abuse and no currently accepted medical use in treatment in the U.S. The pure compound, mescaline, as well as the Peyote cactus (Lophophora williamsii), are explicitly listed as Schedule I substances.
A significant legal exception exists for the ceremonial use of Peyote by the Native American Church (NAC). This exemption is codified in federal law through the American Indian Religious Freedom Act Amendments of 1994 (AIRFAA). The amendments protect the traditional, ceremonial use, possession, and transportation of Peyote by members of federally recognized Indian tribes. This legislative action followed a 1990 Supreme Court ruling that had previously weakened constitutional protections for religious use of Peyote.
The legal status of other mescaline-containing cacti, such as the San Pedro cactus (Echinopsis pachanoi), differs from Peyote. While the pure mescaline compound extracted from any source is illegal, the San Pedro cactus itself is not specifically scheduled under the CSA. Since San Pedro is widely sold as an ornamental plant, its possession and cultivation is generally tolerated, provided there is no intent to extract the controlled compound or prepare it for human consumption.