A psychoactive drug, psychopharmaceutical, mind-altering drug, consciousness-altering drug, psychoactive substance, or psychotropic substance is a chemical substance that alters psychological functioning by modulating central nervous system (CNS) activity. Psychoactive and psychotropic drugs both affect the brain, with psychotropics sometimes referring to psychiatric drugs or high-abuse substances. Novel psychoactive substances are designer drugs made to mimic illegal ones and bypass laws.
Psychoactive drug use dates back to prehistory for medicinal, recreational, or religious purposes, with evidence of widespread cultural use. Many animals intentionally consume psychoactive substances, and some traditional legends suggest animals first introduced humans to their use. Psychoactive substances are used across cultures for purposes ranging from medicinal and therapeutic treatment of mental disorders and pain, to performance enhancement. Their effects are influenced by the drug itself, the environment, and individual factors. Psychoactive drugs are categorized by their pharmacological effects into types such as anxiolytics (reduce anxiety), entactogens (enhance empathy), stimulants (increase CNS activity), depressants (decrease CNS activity), and hallucinogens (alter perception and emotions). Psychoactive drugs are administered through various routes—including oral ingestion, injection, rectal use, and inhalation—with the method and efficiency differing by drug.
Psychoactive drugs alter brain function by interacting with neurotransmitter systems—either enhancing or inhibiting activity—which can affect mood, perception, cognition, behavior, and potentially lead to dependence or long-term neural adaptations such as sensitization or tolerance. Addiction and dependence involve psychological and physical reliance on psychoactive substances, with treatments ranging from psychotherapy and medication to emerging psychedelic therapies; global prevalence is highest for alcohol, cannabis, and opioid use disorders.
The legality of psychoactive drugs has long been controversial, shaped by international treaties like the 1961 Single Convention on Narcotic Drugs and national laws such as the United States Controlled Substances Act. Distinctions are made between recreational and medical use. Enforcement varies across countries. While the 20th century saw global criminalization, recent shifts favor harm reduction and regulation over prohibition. Widely used psychoactive drugs include typically legal recreational substances like caffeine, alcohol, and nicotine; prescription-only medications such as SSRIs, opioids, and benzodiazepines; and typically illegal drugs like cannabis, cocaine, and psychedelics.
History
Psychoactive drug use can be traced to prehistory. Archaeological evidence of the use of psychoactive substances, mostly plants, dates back at least 10,000 years; historical evidence indicates cultural use 5,000 years ago. There is evidence of the chewing of coca leaves, for example, in Peruvian society 8,000 years ago.Early Holocene coca chewing in northern Peru Volume: 84 Number: 326 Page: 939–953
Psychoactive substances have been used medicinally and to alter consciousness. Consciousness altering may be a primary drive, akin to the need to satiate thirst, hunger, or sexual desire. This may be manifest in the long history of drug use, and even in children's desire for spinning, swinging, or sliding, suggesting that the drive to alter one's state of mind is universal.
In The Hasheesh Eater (1857), American author Fitz Hugh Ludlow was one of the first to describe in modern terms the desire to change one's consciousness through drug use:
During the 20th century, the majority of countries initially responded to the use of recreational drugs by prohibiting production, distribution, or use through criminalization. A notable example occurred with Prohibition in the United States, where early in the century alcohol was made illegal for 13 years. In recent decades, an emerging perspective among governments and law enforcement holds that illicit drug use cannot be stopped through prohibition. One organization holding that view, Law Enforcement Against Prohibition (LEAP), concluded that "[in] fighting a war on drugs the government has increased the problems of society and made them far worse. A system of regulation rather than prohibition is a less harmful, more ethical and a more effective public policy."
In some countries and localities, there has been a move away from prohibition and towards harm reduction, where the use of illicit drugs is neither condoned nor promoted, but services and support are provided to ensure users have adequate factual information readily available and to minimize, or eliminate, negative effects of their use. Such is the case with Portugal's drug policy of decriminalization and harm reduction, with a primary goal of reducing the adverse health effects of drug use.
Terminology Psychoactive and psychotropic are often used interchangeably in general and academic sources, to describe substances that act on the brain to alter cognition and perception; some sources make a distinction between the terms. One narrower definition of psychotropic refers to drugs used to treat mental disorders, such as anxiolytic sedatives, antidepressants, antimanic agents, and neuroleptics. Another usage of psychotropic refers to substances determined to pose "high abuse liability", including stimulants, hallucinogens, opioids, and sedatives/hypnotics including alcohol. In international drug control, psychotropic substances refers to the substances specified in the Convention on Psychotropic Substances, which does not include narcotics.
The term "drug" has become a skunked term. "Drugs" can have a negative connotation, often associated with illegal substances like cocaine or heroin, despite the fact that the terms "drug" and "medicine" are sometimes used interchangeably.
Novel psychoactive substances (NPS), also known as "designer drugs" are a category of psychoactive drugs (substances) that are designed to mimic the effects of often illegal drugs, usually in efforts to circumvent existing drug laws.
Types Psychoactive drugs are divided according to their pharmacological effects. Common subtypes include:
Anxiolytics are medicinally used to reduce the symptoms of anxiety, and sometimes insomnia. Examples: benzodiazepines such as Xanax and Valium; barbiturates
Entactogens alter emotional state, often resulting in an increased sense of empathy, closeness, and emotional communication. Example: MDMA (ecstasy), MDA, 6-APB, AMT
Stimulants increase activity, or arousal, of the central nervous system. They can enhance alertness, attention, cognition, mood and physical performance. Some stimulants are used medicinally to treat individuals with ADHD and narcolepsy. Examples: amphetamine, caffeine, cocaine, nicotine
Depressants reduce, or depress, activity and stimulation in the central nervous system. This category encompasses a spectrum of substances with sedative, soporific, and anesthetic properties, and include sedatives, hypnotics, and opioids. Examples: ethanol (alcohol), opioids such as morphine, fentanyl, and codeine, barbiturates, benzodiazepines, GHB
Hallucinogens, including psychedelics, dissociatives and deliriants, encompass substances that produce distinct alterations in perception, sensation of space and time, and emotional state. Examples, psychedelics: psilocybin, LSD, DMT, mescaline Examples, dissociatives: dextromethorphan, salvinorin A, ketamine Examples, deliriants: scopolamine, diphenhydramine
Uses
The ways in which psychoactive substances are used vary widely between cultures. Some substances may have controlled or illegal uses, others may have shamanic purposes, and others are used medicinally. Examples include social drinking, nootropic supplements, and sleep aids. Caffeine is the world's most widely consumed psychoactive substance, and is legal and unregulated in nearly all jurisdictions; in North America, 90% of adults consume caffeine daily.
Mental disorders
Psychiatric medications are psychoactive drugs prescribed for the management of mental and emotional disorders, or to aid in overcoming challenging behavior. There are six major classes of psychiatric medications: Antidepressants treat disorders such as clinical depression, dysthymia, anxiety, eating disorders, and borderline personality disorder. Stimulants, used to treat disorders such as attention deficit hyperactivity disorder and narcolepsy, and for weight reduction. Antipsychotics, used to treat psychotic symptoms, such as those associated with schizophrenia or severe mania, or as adjuncts to relieve clinical depression. Mood stabilizers, used to treat bipolar disorder and schizoaffective disorder. Anxiolytics, used to treat anxiety disorders. Depressants, used as hypnotics, sedatives, and anesthetics, depending upon dosage.
In addition, several psychoactive substances are currently employed to treat various addictions. These include acamprosate or naltrexone in the treatment of alcoholism, or methadone or buprenorphine maintenance therapy in the case of opioid addiction.
Exposure to psychoactive drugs can cause changes to the brain that counteract or augment some of their effects; these changes may be beneficial or harmful. However, there is a significant amount of evidence that the relapse rate of mental disorders negatively corresponds with the length of properly followed treatment regimens (that is, relapse rate substantially declines over time), and to a much greater degree than placebo.
Military
Drugs used by militaries
Militaries worldwide have used or are using various psychoactive drugs to treat pain and to improve performance of soldiers by suppressing hunger, increasing the ability to sustain effort without food, increasing and lengthening wakefulness and concentration, suppressing fear, reducing empathy, and improving reflexes and memory-recall among other things.
Both military and civilian American intelligence officials are known to have used psychoactive drugs while interrogating captives apprehended in its "war on terror". In July 2012 Jason Leopold and Jeffrey Kaye, psychologists and human rights workers, had a Freedom of Information Act request fulfilled that confirmed that the use of psychoactive drugs during interrogation was a long-standing practice. Captives and former captives had been reporting medical staff collaborating with interrogators to drug captives with powerful psychoactive drugs prior to interrogation since the very first captives release. In May 2003 recently released Pakistani captive Sha Mohammed Alikhel described the routine use of psychoactive drugs. He said that Jihan Wali, a captive kept in a nearby cell, was rendered catatonic through the use of these drugs.
Alcohol has a long association of military use, and has been called "liquid courage" for its role in preparing troops for battle, anaesthetize injured soldiers, and celebrate military victories. It has also served as a coping mechanism for combat stress reactions and a means of decompression from combat to everyday life. However, this reliance on alcohol can have negative consequences for physical and mental health.
The first documented case of a soldier overdosing on methamphetamine during combat, was the Finnish corporal Aimo Koivunen, a soldier who fought in the Winter War and the Continuation War.
Psychochemical warfare
Psychoactive drugs have been used in military applications as non-lethal weapons.
Pain management