A psychoactive substance is a chemical substance—other than a nutrient or essential dietary ingredient—that alters brain function to produce temporary changes in sensation, perception, mood, consciousness, cognition, and behavior.
Psychoactive substances have been used by humans for a variety of purposes since recorded history. For example, they may be used as medicine, as recreational substances for their euphoric effects and novelty value, as entheogens for ritual or spiritual purposes, or as scientific research probes for studying the brain and mind. The latter two have particular relevance for practitioners of psychonautics.
The Psychoactive Substance Index (PSI) is designed to catalog and provide relevant, accurate, and unbiased information for any and all mind-altering substances known to humankind, with a special focus on those with potential applications as mind-expanding tools.
The individual articles detail not just the history, chemistry, pharmacology, toxicity, and legality of each substance, but also its user-reported subjective effects (i.e. phenomenology). This is achieved in accordance with a standardized system of definitions and terminologies proposed in the Subjective Effect Index (SEI).
Please see our summary index to view conveniently condensed versions of each article.
Note: This list should only include substances that have a documented history of human use. Do not include substances that are merely theoretical or lack reliable user experience reports and data!