A drug is any

chemical substance A chemical substance is a form of matter having constant chemical composition and characteristic properties. Some references add that chemical substance cannot be separated into its constituent elements by physical separation methods, i.e., wi ...

that causes a change in an organism's

physiology Physiology (; ) is the scientific study of functions and mechanisms in a living system. As a sub-discipline of biology, physiology focuses on how organisms, organ systems, individual organs, cells, and biomolecules carry out the chemical ...

psychology Psychology is the scientific study of mind and behavior. Psychology includes the study of conscious and unconscious phenomena, including feelings and thoughts. It is an academic discipline of immense scope, crossing the boundaries betwe ...

when consumed. Drugs are typically distinguished from

food Food is any substance consumed by an organism for nutritional support. Food is usually of plant, animal, or fungal origin, and contains essential nutrients, such as carbohydrates, fats, proteins, vitamins, or minerals. The substance is inge ...

and substances that provide nutritional support. Consumption of drugs can be via

inhalation Inhalation (or Inspiration) happens when air or other gases enter the lungs. Inhalation of air Inhalation of air, as part of the cycle of breathing, is a vital process for all human life. The process is autonomic (though there are exceptions ...

injection Injection or injected may refer to: Science and technology * Injective function, a mathematical function mapping distinct arguments to distinct values * Injection (medicine), insertion of liquid into the body with a syringe * Injection, in broadca ...

smoking Smoking is a practice in which a substance is burned and the resulting smoke is typically breathed in to be tasted and absorbed into the bloodstream. Most commonly, the substance used is the dried leaves of the tobacco plant, which have bee ...

ingestion Ingestion is the consumption of a substance by an organism. In animals, it normally is accomplished by taking in a substance through the mouth into the gastrointestinal tract, such as through eating or drinking. In single-celled organisms ingest ...

absorption Absorption may refer to: Chemistry and biology * Absorption (biology), digestion **Absorption (small intestine) *Absorption (chemistry), diffusion of particles of gas or liquid into liquid or solid materials *Absorption (skin), a route by which ...

via a

patch Patch or Patches may refer to: Arts, entertainment and media * Patch Johnson, a fictional character from ''Days of Our Lives'' * Patch (''My Little Pony''), a toy * "Patches" (Dickey Lee song), 1962 * "Patches" (Chairmen of the Board song) ...

on the skin,

suppository A suppository is a dosage form used to deliver medications by insertion into a body orifice where it dissolves or melts to exert local or systemic effects. There are three types of suppositories, each to insert into a different sections: rectal su ...

, or dissolution under the tongue. In

pharmacology Pharmacology is a branch of medicine, biology and pharmaceutical sciences concerned with drug or medication action, where a drug may be defined as any artificial, natural, or endogenous (from within the body) molecule which exerts a biochemica ...

, a drug is a chemical substance, typically of known structure, which, when administered to a living organism, produces a biological effect. A

pharmaceutical drug A medication (also called medicament, medicine, pharmaceutical drug, medicinal drug or simply drug) is a drug used to diagnose, cure, treat, or prevent disease. Drug therapy (pharmacotherapy) is an important part of the medical field and re ...

, also called a medication or medicine, is a chemical substance used to treat,

cure A cure is a substance or procedure that ends a medical condition, such as a medication, a surgical operation, a change in lifestyle or even a philosophical mindset that helps end a person's sufferings; or the state of being healed, or cured. The ...

prevent Prevention may refer to: Health and medicine * Preventive healthcare, measures to prevent diseases or injuries rather than curing them or treating their symptoms General safety * Crime prevention, the attempt to reduce deter crime and crimin ...

, or

diagnose Diagnosis is the identification of the nature and cause of a certain phenomenon. Diagnosis is used in many different disciplines, with variations in the use of logic, analytics, and experience, to determine " cause and effect". In systems enginee ...

disease A disease is a particular abnormal condition that negatively affects the structure or function of all or part of an organism, and that is not immediately due to any external injury. Diseases are often known to be medical conditions that a ...

or to promote

well-being Well-being, or wellbeing, also known as wellness, prudential value or quality of life, refers to what is intrinsically valuable relative ''to'' someone. So the well-being of a person is what is ultimately good ''for'' this person, what is in th ...

. Traditionally drugs were obtained through extraction from

medicinal plants Medicinal plants, also called medicinal herbs, have been discovered and used in traditional medicine practices since prehistoric times. Plants synthesize hundreds of chemical compounds for various functions, including defense and protection ag ...

, but more recently also by

organic synthesis Organic synthesis is a special branch of chemical synthesis and is concerned with the intentional construction of organic compounds. Organic molecules are often more complex than inorganic compounds, and their synthesis has developed into one o ...

. Pharmaceutical drugs may be used for a limited duration, or on a regular basis for chronic disorders. Pharmaceutical drugs are often classified into

drug class A drug class is a set of medications and other compounds that have a similar chemical structures, the same mechanism of action (i.e. binding to the same biological target), a related mode of action, and/or are used to treat the same disease. In ...

es—groups of related drugs that have similar

chemical structure A chemical structure determination includes a chemist's specifying the molecular geometry and, when feasible and necessary, the electronic structure of the target molecule or other solid. Molecular geometry refers to the spatial arrangement of at ...

s, the same

mechanism of action In pharmacology, the term mechanism of action (MOA) refers to the specific biochemical interaction through which a drug substance produces its pharmacological effect. A mechanism of action usually includes mention of the specific molecular targe ...

(binding to the same

biological target A biological target is anything within a living organism to which some other entity (like an endogenous ligand or a drug) is directed and/or binds, resulting in a change in its behavior or function. Examples of common classes of biological targets ...

), a related

mode of action A mode of action (MoA) describes a functional or anatomical change, resulting from the exposure of a living organism to a substance. In comparison, a mechanism of action (MOA) describes such changes at the molecular level. A mode of action is impor ...

, and that are used to treat the same disease. The

Anatomical Therapeutic Chemical Classification System The Anatomical Therapeutic Chemical (ATC) Classification System is a drug classification system that classifies the active ingredients of drugs according to the organ or system on which they act and their therapeutic, pharmacological and chemical ...

(ATC), the most widely used drug classification system, assigns drugs a unique

ATC code The Anatomical Therapeutic Chemical (ATC) Classification System is a drug classification system that classifies the active ingredients of drugs according to the organ or system on which they act and their therapeutic, pharmacological and chemical ...

, which is an alphanumeric code that assigns it to specific drug classes within the ATC system. Another major classification system is the

Biopharmaceutics Classification System The Biopharmaceutics Classification System is a system to differentiate the drugs on the basis of their solubility and permeability. This system restricts the prediction using the parameters solubility and intestinal permeability. The solubility ...

. This classifies drugs according to their solubility and permeability or

properties.

Psychoactive drug A psychoactive drug, psychopharmaceutical, psychoactive agent or psychotropic drug is a chemical substance, that changes functions of the nervous system, and results in alterations in perception, mood, consciousness, cognition or behavior. ...

s are chemical substances that affect the function of the

central nervous system The central nervous system (CNS) is the part of the nervous system consisting primarily of the brain and spinal cord. The CNS is so named because the brain integrates the received information and coordinates and influences the activity of all par ...

, altering

perception Perception () is the organization, identification, and interpretation of sensory information in order to represent and understand the presented information or environment. All perception involves signals that go through the nervous system ...

, mood or

consciousness Consciousness, at its simplest, is sentience and awareness of internal and external existence. However, the lack of definitions has led to millennia of analyses, explanations and debates by philosophers, theologians, linguisticians, and scien ...

. These drugs are divided into different groups like:

stimulant Stimulants (also often referred to as psychostimulants or colloquially as uppers) is an overarching term that covers many drugs including those that increase activity of the central nervous system and the body, drugs that are pleasurable and inv ...

depressant A depressant, or central depressant, is a drug that lowers neurotransmission levels, which is to depress or reduce arousal or stimulation, in various areas of the brain. Depressants are also colloquially referred to as downers as they lower the ...

antidepressant Antidepressants are a class of medication used to treat major depressive disorder, anxiety disorders, chronic pain conditions, and to help manage addictions. Common side-effects of antidepressants include dry mouth, weight gain, dizziness, hea ...

anxiolytic An anxiolytic (; also antipanic or antianxiety agent) is a medication or other intervention that reduces anxiety. This effect is in contrast to anxiogenic agents which increase anxiety. Anxiolytic medications are used for the treatment of anxi ...

antipsychotic Antipsychotics, also known as neuroleptics, are a class of Psychiatric medication, psychotropic medication primarily used to manage psychosis (including delusions, hallucinations, paranoia or disordered thought), principally in schizophrenia but ...

s, and

hallucinogen Hallucinogens are a large, diverse class of psychoactive drugs that can produce altered states of consciousness characterized by major alterations in thought, mood, and perception as well as other changes. Most hallucinogens can be categorized ...

s. These psychoactive drugs have been proven useful in treating wide range of

medical conditions A disease is a particular abnormal condition that negatively affects the structure or function (biology), function of all or part of an organism, and that is not immediately due to any external injury. Diseases are often known to be medica ...

including

mental disorder A mental disorder, also referred to as a mental illness or psychiatric disorder, is a behavioral or mental pattern that causes significant distress or impairment of personal functioning. Such features may be persistent, relapsing and remitti ...

s around the world. The most widely used drugs in the world include

caffeine Caffeine is a central nervous system (CNS) stimulant of the methylxanthine class. It is mainly used recreationally as a cognitive enhancer, increasing alertness and attentional performance. Caffeine acts by blocking binding of adenosine t ...

nicotine Nicotine is a natural product, naturally produced alkaloid in the nightshade family of plants (most predominantly in tobacco and ''Duboisia hopwoodii'') and is widely used recreational drug use, recreationally as a stimulant and anxiolytic. As ...

and

alcohol Alcohol most commonly refers to: * Alcohol (chemistry), an organic compound in which a hydroxyl group is bound to a carbon atom * Alcohol (drug), an intoxicant found in alcoholic drinks Alcohol may also refer to: Chemicals * Ethanol, one of sev ...

, which are also considered

recreational drugs Recreation is an activity of leisure, leisure being discretionary time. The "need to do something for recreation" is an essential element of human biology and psychology. Recreational activities are often done for enjoyment, amusement, or pleasur ...

, since they are used for pleasure rather than medicinal purposes. All drugs can have potential

side effect In medicine, a side effect is an effect, whether therapeutic or adverse, that is secondary to the one intended; although the term is predominantly employed to describe adverse effects, it can also apply to beneficial, but unintended, consequence ...

s."MHRA Side Effects of Medicines."
''MHRA Side Effects of Medicines'', Abuse of several psychoactive drugs can cause

addiction Addiction is a neuropsychological disorder characterized by a persistent and intense urge to engage in certain behaviors, one of which is the usage of a drug, despite substantial harm and other negative consequences. Repetitive drug use o ...

and/or

physical dependence Physical dependence is a physical condition caused by chronic use of a tolerance-forming drug, in which abrupt or gradual drug withdrawal causes unpleasant physical symptoms. Physical dependence can develop from low-dose therapeutic use of certai ...

. Excessive use of stimulants can promote

stimulant psychosis Stimulant psychosis is a mental disorder characterized by psychotic symptoms (such as hallucinations, paranoid ideation, delusions, disorganized thinking, grossly disorganized behaviour) which involves and typically occurs following an overdose or ...

. Many recreational drugs are illicit and international treaties such as the

Single Convention on Narcotic Drugs The Single Convention on Narcotic Drugs, 1961 (Single Convention, 1961 Convention, or C61) is an international treaty that controls activities (cultivation, production, supply, trade, transport) of specific narcotic drugs and lays down a syst ...

exist for the purpose of their

prohibition Prohibition is the act or practice of forbidding something by law; more particularly the term refers to the banning of the manufacture, storage (whether in barrels or in bottles), transportation, sale, possession, and consumption of alcoholic ...

Etymology

In English, the noun "drug" is thought to originate from Old French "drogue", possibly deriving from "droge (vate)" from Middle Dutch meaning "dry (barrels)", referring to medicinal plants preserved as dry matter in barrels.

Medication

A ''medication'' or ''medicine'' is a

drug A drug is any chemical substance that causes a change in an organism's physiology or psychology when consumed. Drugs are typically distinguished from food and substances that provide nutritional support. Consumption of drugs can be via insuffla ...

taken to cure or ameliorate any symptoms of an

illness A disease is a particular abnormal condition that negatively affects the structure or function of all or part of an organism, and that is not immediately due to any external injury. Diseases are often known to be medical conditions that ar ...

or medical condition. The use may also be as

preventive medicine Preventive healthcare, or prophylaxis, consists of measures taken for the purposes of disease prevention.Hugh R. Leavell and E. Gurney Clark as "the science and art of preventing disease, prolonging life, and promoting physical and mental hea ...

that has future benefits but does not treat any existing or pre-existing diseases or symptoms. Dispensing of medication is often regulated by

government A government is the system or group of people governing an organized community, generally a state. In the case of its broad associative definition, government normally consists of legislature, executive, and judiciary. Government is a ...

s into three categories—''

over-the-counter Over-the-counter (OTC) drugs are medicines sold directly to a consumer without a requirement for a prescription from a healthcare professional, as opposed to prescription drugs, which may be supplied only to consumers possessing a valid prescr ...

'' medications, which are available in

pharmacies Pharmacy is the science and practice of discovering, producing, preparing, dispensing, reviewing and monitoring medications, aiming to ensure the safe, effective, and affordable use of medicines. It is a miscellaneous science as it links healt ...

and supermarkets without special restrictions; ''

behind-the-counter Over-the-counter (OTC) drugs are medicines sold directly to a consumer without a requirement for a prescription from a healthcare professional, as opposed to prescription drugs, which may be supplied only to consumers possessing a valid prescr ...

'' medicines, which are dispensed by a

pharmacist A pharmacist, also known as a chemist (Commonwealth English) or a druggist (North American and, archaically, Commonwealth English), is a healthcare professional who prepares, controls and distributes medicines and provides advice and instructi ...

without needing a doctor's prescription, and '' prescription only medicines'', which must be prescribed by a licensed

medical professional A health professional, healthcare professional, or healthcare worker (sometimes abbreviated HCW) is a provider of health care treatment and advice based on formal training and experience. The field includes those who work as a nurse, physician (suc ...

, usually a

physician A physician (American English), medical practitioner (Commonwealth English), medical doctor, or simply doctor, is a health professional who practices medicine, which is concerned with promoting, maintaining or restoring health through th ...

. In the United Kingdom, behind-the-counter medicines are called

pharmacy medicine The regulation of therapeutic goods, defined as drugs and therapeutic devices, varies by jurisdiction. In some countries, such as the United States, they are regulated at the national level by a single agency. In other jurisdictions they are reg ...

s which can only be sold in registered pharmacies, by or under the supervision of a pharmacist. These medications are designated by the letter P on the label. The range of medicines available without a prescription varies from country to country. Medications are typically produced by

pharmaceutical companies The pharmaceutical industry discovers, develops, produces, and markets drugs or pharmaceutical drugs for use as medications to be administered to patients (or self-administered), with the aim to cure them, vaccinate them, or alleviate symptoms. ...

and are often

patent A patent is a type of intellectual property that gives its owner the legal right to exclude others from making, using, or selling an invention for a limited period of time in exchange for publishing an enabling disclosure of the invention."A p ...

ed to give the developer exclusive rights to produce them. Those that are not patented (or with expired patents) are called

generic drug A generic drug is a pharmaceutical drug that contains the same chemical substance as a drug that was originally protected by chemical patents. Generic drugs are allowed for sale after the patents on the original drugs expire. Because the active ch ...

s since they can be produced by other companies without restrictions or licenses from the patent holder. Pharmaceutical drugs are usually categorised into

es. A group of drugs will share a similar

, or have the same

, the same related

or target the same illness or related illnesses. The

(ATC), the most widely used drug classification system, assigns drugs a unique

, which is an alphanumeric code that assigns it to specific drug classes within the ATC system. Another major classification system is the

. This groups drugs according to their solubility and permeability or

properties.

Spiritual and religious use

Some religions, particularly

ethnic religion In religious studies, an ethnic religion is a religion or belief associated with a particular ethnic group. Ethnic religions are often distinguished from universal religions, such as Christianity or Islam, in which gaining converts is a pri ...

s, are based completely on the use of certain drugs, known as

entheogens Entheogens are psychoactive substances that induce alterations in perception, mood, consciousness, cognition, or behavior for the purposes of engendering spiritual development or otherwiseRätsch, Christian, ''The Encyclopedia of Psychoacti ...

, which are mostly

s,—

psychedelics Psychedelics are a subclass of hallucinogenic drugs whose primary effect is to trigger non-ordinary states of consciousness (known as psychedelic experiences or "trips").Pollan, Michael (2018). ''How to Change Your Mind: What the New Science of ...

dissociative Dissociatives, colloquially dissos, are a subclass of hallucinogens which distort perception of sight and sound and produce feelings of detachment – dissociation – from the environment and/or self. Although many kinds of drugs are capable of ...

s, or

deliriant Deliriants are a subclass of hallucinogen. The term was coined in the early 1980s to distinguish these drugs from psychedelics and dissociatives such as LSD and ketamine, respectively, due to their primary effect of causing delirium, as opposed t ...

s. Some drugs used as entheogens include

kava Kava or kava kava (''Piper methysticum'': Latin 'pepper' and Latinized Greek 'intoxicating') is a crop of the Pacific Islands. The name ''kava'' is from Tongan and Marquesan, meaning 'bitter'; other names for kava include ''ʻawa'' (Hawaiʻi), ...

which can act as a

, a

sedative A sedative or tranquilliser is a substance that induces sedation by reducing irritability or excitement. They are CNS depressants and interact with brain activity causing its deceleration. Various kinds of sedatives can be distinguished, but t ...

, a

euphoriant Euphoria ( ) is the experience (or affect) of pleasure or excitement and intense feelings of well-being and happiness. Certain natural rewards and social activities, such as aerobic exercise, laughter, listening to or making music and danci ...

and an

anesthetic An anesthetic (American English) or anaesthetic (British English; see spelling differences) is a drug used to induce anesthesia ⁠— ⁠in other words, to result in a temporary loss of sensation or awareness. They may be divided into two ...

. The roots of the kava plant are used to produce a drink which is consumed throughout the cultures of the Pacific Ocean. Some

shamans Shamanism is a religious practice that involves a practitioner (shaman) interacting with what they believe to be a spirit world through altered states of consciousness, such as trance. The goal of this is usually to direct spirits or spiritu ...

from different cultures use entheogens, defined as "generating the divine within" to achieve

religious ecstasy Religious ecstasy is a type of altered state of consciousness characterized by greatly reduced external awareness and expanded interior mental and spiritual awareness, frequently accompanied by visions and emotional (and sometimes physical) eup ...

. Amazonian shamans use

ayahuasca AyahuascaPronounced as in the UK and in the US. Also occasionally known in English as ''ayaguasca'' (Spanish-derived), ''aioasca'' (Brazilian Portuguese-derived), or as ''yagé'', pronounced or . Etymologically, all forms but ''yagé'' descen ...

(yagé) a hallucinogenic brew for this purpose.

Mazatec shamans The Mazatec Shamans are known for their ritual use of psilocybin mushrooms, psychoactive morning glory seeds, and ''Salvia divinorum''. María Sabina was one of the best known of the Mazatec Shamans. Her healing psilocybin mushroom ceremonies, call ...

have a long and continuous tradition of religious use of ''

Salvia divinorum ''Salvia divinorum'' (Latin: "sage of the diviners"; also called ska maría pastora, seer's sage, yerba de la pastora, magic mint or simply salvia) is a plant species with transient psychoactive properties when its leaves are consumed by che ...

'' a

psychoactive A psychoactive drug, psychopharmaceutical, psychoactive agent or psychotropic drug is a chemical substance, that changes functions of the nervous system, and results in alterations in perception, mood, consciousness, cognition or behavior. Th ...

plant. Its use is to facilitate visionary states of consciousness during spiritual healing sessions. Valdés, Díaz & Paul 1983, p. 287.

Silene undulata ''Silene undulata'' ( xh, iindlela zimhlophe—"white ways/paths", also known as ''Silene capensis'', and African dream root) is a plant native to the Eastern Cape of South Africa. Cultivation In cultivation, ''S. undulata'' is an easily grown ...

is regarded by the

Xhosa people The Xhosa people, or Xhosa language, Xhosa-speaking people (; ) are African people who are direct kinsmen of Tswana people, Sotho people and Twa people, yet are narrowly sub grouped by European as Nguni people, Nguni ethnic group whose traditi ...

as a sacred plant and used as an entheogen. Its roots are traditionally used to induce vivid (and according to the Xhosa, prophetic)

lucid dreams A lucid dream is a type of dream in which the dreamer becomes aware that they are dreaming while dreaming. During a lucid dream, the dreamer may gain some amount of control over the dream characters, narrative, or environment; however, this is n ...

during the initiation process of

, classifying it a naturally occurring

oneirogen An oneirogen, from the Greek ὄνειρος ''óneiros'' meaning "dream" and ''gen'' "to create", is that which produces or enhances dreamlike states of consciousness. This is characterized by an immersive dream state similar to REM sleep, which ...

similar to the more well-known dream herb ''

Calea ternifolia ''Calea ternifolia'' ( syn. ''Calea zacatechichi'') is a species of flowering plant in the aster family, Asteraceae. It is native to Mexico and Central America. Its English language common names include bitter-grass, Mexican calea, and dream herb ...

''.

Peyote The peyote (; ''Lophophora williamsii'' ) is a small, spineless cactus which contains psychoactive alkaloids, particularly mescaline. ''Peyote'' is a Spanish word derived from the Nahuatl (), meaning "caterpillar cocoon", from a root , "to gl ...

, a small spineless

cactus A cactus (, or less commonly, cactus) is a member of the plant family Cactaceae, a family comprising about 127 genera with some 1750 known species of the order Caryophyllales. The word ''cactus'' derives, through Latin, from the Ancient Greek ...

, has been a major source of psychedelic

mescaline Mescaline or mescalin (3,4,5-trimethoxyphenethylamine) is a naturally occurring psychedelic protoalkaloid of the substituted phenethylamine class, known for its hallucinogenic effects comparable to those of LSD and psilocybin. Biological sou ...

and has probably been used by Native Americans for at least five thousand years. Most mescaline is now obtained from a few species of columnar cacti in particular from San Pedro and not from the vulnerable peyote. The

entheogenic use of cannabis Cannabis has served as an entheogen—a chemical substance used in religious or spiritual contexts—in the Indian subcontinent since the Vedic period dating back to approximately 1500 BCE, but perhaps as far back as 2000 BCE. It was introduce ...

has also been widely practised for centuries.

Rastafari Rastafari, sometimes called Rastafarianism, is a religion that developed in Jamaica during the 1930s. It is classified as both a new religious movement and a social movement by scholars of religion. There is no central authority in control of ...

use

marijuana Cannabis, also known as marijuana among other names, is a psychoactive drug from the cannabis plant. Native to Central or South Asia, the cannabis plant has been used as a drug for both recreational and entheogenic purposes and in various tra ...

(ganja) as a

sacrament A sacrament is a Christianity, Christian Rite (Christianity), rite that is recognized as being particularly important and significant. There are various views on the existence and meaning of such rites. Many Christians consider the sacraments ...

in their religious ceremonies. Psychedelic mushrooms (

psilocybin mushroom Psilocybin mushrooms, commonly known as magic mushrooms, are a polyphyletic informal group of mushroom, fungi that contain psilocybin which turns into psilocin upon ingestion. Biological genera containing psilocybin mushrooms include ''Psilocyb ...

s), commonly called ''magic mushrooms'' or ''shrooms'' have also long been used as entheogens.

Smart drugs and designer drugs

Nootropic Nootropics ( , or ) (colloquial: smart drugs and cognitive enhancers, similar to adaptogens) are a wide range of natural or synthetic supplements or drugs and other substances that are claimed to improve cognitive function or to promote re ...

s, also commonly referred to as "smart drugs", are drugs that are claimed to improve human cognitive abilities. Nootropics are used to improve memory, concentration, thought, mood, and learning. An increasingly used nootropic among students, also known as a ''study drug'', is

methylphenidate Methylphenidate, sold under the brand names Ritalin and Concerta among others, is the most widely prescribed central nervous system (CNS) stimulant medication used to treat attention deficit hyperactivity disorder (ADHD) and, to a lesser extent, ...

branded commonly as ''Ritalin'' and used for the treatment of

attention deficit hyperactivity disorder Attention deficit hyperactivity disorder (ADHD) is a neurodevelopmental disorder characterised by excessive amounts of inattention, hyperactivity, and impulsivity that are pervasive, impairing in multiple contexts, and otherwise age-inap ...

(ADHD) and

narcolepsy Narcolepsy is a long-term neurological disorder that involves a decreased ability to regulate sleep–wake cycles. Symptoms often include periods of excessive daytime sleepiness and brief involuntary sleep episodes. About 70% of those affec ...

. At high doses methylphenidate can become highly addictive. Serious addiction can lead to

psychosis Psychosis is a condition of the mind that results in difficulties determining what is real and what is not real. Symptoms may include delusions and hallucinations, among other features. Additional symptoms are incoherent speech and behavior ...

anxiety Anxiety is an emotion which is characterized by an unpleasant state of inner turmoil and includes feelings of dread over anticipated events. Anxiety is different than fear in that the former is defined as the anticipation of a future threat wh ...

and heart problems, and the use of this drug is related to a rise in suicides, and overdoses. Evidence for use outside of student settings is limited but suggests that it is commonplace. Intravenous use of methylphenidate can lead to emphysematous damage to the lungs, known as ''

Ritalin lung Emphysema, or pulmonary emphysema, is a lower respiratory tract disease, characterised by air-filled spaces ( pneumatoses) in the lungs, that can vary in size and may be very large. The spaces are caused by the breakdown of the walls of the alve ...

''. Other drugs known as

designer drug A designer drug is a structural or functional analog of a controlled substance that has been designed to mimic the pharmacological effects of the original drug, while avoiding classification as illegal and/or detection in standard drug tests. Des ...

s are produced. An early example of what today would be labelled a 'designer drug' was

LSD Lysergic acid diethylamide (LSD), also known colloquially as acid, is a potent psychedelic drug. Effects typically include intensified thoughts, emotions, and sensory perception. At sufficiently high dosages LSD manifests primarily mental, vi ...

, which was synthesised from

ergot Ergot ( ) or ergot fungi refers to a group of fungi of the genus ''Claviceps''. The most prominent member of this group is ''Claviceps purpurea'' ("rye ergot fungus"). This fungus grows on rye and related plants, and produces alkaloids that ca ...

. Other examples include analogs of

performance-enhancing drugs Performance-enhancing substances, also known as performance-enhancing drugs (PEDs), are substances that are used to improve any form of activity performance in humans. A well-known example of cheating in sports involves doping in sport, where bann ...

such as designer

steroids A steroid is a biologically active organic compound with four rings arranged in a specific molecular configuration. Steroids have two principal biological functions: as important components of cell membranes that alter membrane fluidity; and a ...

taken to improve physical capabilities and these are sometimes used (legally or not) for this purpose, often by professional athletes. Other designer drugs mimic the effects of psychoactive drugs. Since the late 1990s there has been the identification of many of these synthesised drugs. In Japan and the United Kingdom this has spurred the addition of many designer drugs into a newer class of controlled substances known as a

temporary class drug A temporary class drug is a relatively new status for controlled drugs, which has been adopted in some jurisdictions, notably New Zealand and the United Kingdom, to attempt to bring newly synthesised designer drugs under legal control. The control ...

Synthetic cannabinoid Synthetic cannabinoids are a class of designer drug molecules that bind to the same receptors to which cannabinoids (THC, CBD and many others) in cannabis plants attach. These novel psychoactive substances should not be confused with synthetic ...

s have been produced for a longer period of time and are used in the designer drug synthetic cannabis.

Recreational drug use

Recreational drug use Recreational drug use indicates the use of one or more psychoactive drugs to induce an altered state of consciousness either for pleasure or for some other casual purpose or pastime by modifying the perceptions and emotions of the user. When a ...

is the use of a drug (legal, controlled, or illegal) with the primary intention of altering the state of consciousness through alteration of the central nervous system in order to create positive emotions and feelings. The hallucinogen

is a psychoactive drug commonly used as a recreational drug.

Ketamine Ketamine is a dissociative anesthetic used medically for induction and maintenance of anesthesia. It is also used as a recreational drug. It is one of the safest anesthetics, as, in contrast with opiates, ether, and propofol, it suppresses ne ...

is a drug used for

anesthesia Anesthesia is a state of controlled, temporary loss of sensation or awareness that is induced for medical or veterinary purposes. It may include some or all of analgesia (relief from or prevention of pain), paralysis (muscle relaxation), ...

, and is also used as a recreational drug, both in powder and liquid form, for its hallucinogenic and dissociative effects. Some national laws prohibit the use of different recreational drugs; and medicinal drugs that have the potential for recreational use are often heavily regulated. However, there are many recreational drugs that are legal in many jurisdictions and widely culturally accepted.

Cannabis ''Cannabis'' () is a genus of flowering plants in the family Cannabaceae. The number of species within the genus is disputed. Three species may be recognized: ''Cannabis sativa'', '' C. indica'', and '' C. ruderalis''. Alternatively ...

is the most commonly consumed controlled recreational drug in the world (as of 2012). Its use in many countries is illegal but is legally used in several countries usually with the proviso that it can only be used for personal use. It can be used in the ''leaf'' form of

''(grass)'', or in the resin form of

hashish Hashish ( ar, حشيش, ()), also known as hash, "dry herb, hay" is a drug made by compressing and processing parts of the cannabis plant, typically focusing on flowering buds (female flowers) containing the most trichomes. European Monitorin ...

. Marijuana is a more mild form of cannabis than hashish. There may be an age restriction on the consumption and purchase of legal recreational drugs. Some recreational drugs that are legal and accepted in many places include

tobacco Tobacco is the common name of several plants in the genus '' Nicotiana'' of the family Solanaceae, and the general term for any product prepared from the cured leaves of these plants. More than 70 species of tobacco are known, but the ...

betel nut The betel (''Piper betle'') is a vine of the family Piperaceae, which includes pepper and kava. The betel plant is native to Southeast Asia. It is an evergreen, dioecious perennial, with glossy heart-shaped leaves and white catkins. Betel plan ...

, and

products, and in some areas of the world the legal use of drugs such as

khat Khat or qat ( ''ch’at''; Oromo: ''Jimaa'', so, qaad, khaad, khat or chat, ar, القات ''al-qāt'') is a flowering plant native to eastern and southern Africa. Khat contains the alkaloid cathinone, a stimulant, which is said to cause e ...

is common. There are a number of legal intoxicants commonly called ''legal highs'' that are used recreationally. The most widely used of these is alcohol.

Administration of drugs

All drugs, can be administered via a number of routes, and many can be administered by more than one.

Control of drugs

There are numerous governmental offices in many countries that deal with the control and oversee of drug manufacture and use, and the implementation of various drug laws. The

is an international

treaty A treaty is a formal, legally binding written agreement between actors in international law. It is usually made by and between sovereign states, but can include international organizations An international organization or international o ...

brought about in 1961 to prohibit the use of narcotics save for those used in

medical research Medical research (or biomedical research), also known as experimental medicine, encompasses a wide array of research, extending from "basic research" (also called ''bench science'' or ''bench research''), – involving fundamental scientif ...

and treatment. In 1971, a second treaty the

Convention on Psychotropic Substances The Convention on Psychotropic Substances of 1971 is a United Nations treaty designed to control psychoactive drugs such as #Amphetamine-type stimulants, amphetamine-type stimulants, barbiturates, benzodiazepines, and Psychedelic drug, psychede ...

had to be introduced to deal with newer recreational psychoactive and psychedelic drugs. The

legal status of Salvia divinorum '' Salvia divinorum'', a psychoactive plant, is legal in most countries. Exceptions, countries where there is some form of control, include Australia, Belgium, Brazil, Canada, Denmark, Estonia, Finland, Germany, Iceland, Ireland, Italy, Japa ...

varies in many countries and even in states within the United States. Where it is legislated against the degree of prohibition also varies. The

Food and Drug Administration The United States Food and Drug Administration (FDA or US FDA) is a List of United States federal agencies, federal agency of the United States Department of Health and Human Services, Department of Health and Human Services. The FDA is respon ...

(FDA) in the United States is a federal agency responsible for protecting and promoting

public health Public health is "the science and art of preventing disease, prolonging life and promoting health through the organized efforts and informed choices of society, organizations, public and private, communities and individuals". Analyzing the det ...

through the

regulation Regulation is the management of complex systems according to a set of rules and trends. In systems theory, these types of rules exist in various fields of biology and society, but the term has slightly different meanings according to context. For ...

and supervision of

food safety Food safety (or food hygiene) is used as a scientific method/discipline describing handling, preparation, and storage of food in ways that prevent food-borne illness. The occurrence of two or more cases of a similar illness resulting from t ...

tobacco products Tobacco is the agricultural product of the leaves of plants in the genus ''Nicotiana'', commonly termed ''tobacco plants''. All species of ''Nicotiana'' contain the addictive drug nicotine—a psychostimulant alkaloid found in all parts of the ...

dietary supplement A dietary supplement is a manufactured product intended to supplement one's diet by taking a pill, capsule, tablet, powder, or liquid. A supplement can provide nutrients either extracted from food sources or that are synthetic in order ...

s, prescription and

medications A medication (also called medicament, medicine, pharmaceutical drug, medicinal drug or simply drug) is a drug used to diagnose, cure, treat, or prevent disease. Drug therapy (pharmacotherapy) is an important part of the medical field and rel ...

vaccine A vaccine is a biological Dosage form, preparation that provides active acquired immunity to a particular infectious disease, infectious or cancer, malignant disease. The safety and effectiveness of vaccines has been widely studied and verifie ...

biopharmaceutical A biopharmaceutical, also known as a biological medical product, or biologic, is any pharmaceutical drug product manufactured in, extracted from, or semisynthesized from biological sources. Different from totally synthesized pharmaceuticals, t ...

blood transfusion Blood transfusion is the process of transferring blood products into a person's circulation intravenously. Transfusions are used for various medical conditions to replace lost components of the blood. Early transfusions used whole blood, but mo ...

medical device A medical device is any device intended to be used for medical purposes. Significant potential for hazards are inherent when using a device for medical purposes and thus medical devices must be proved safe and effective with reasonable assura ...

electromagnetic radiation In physics, electromagnetic radiation (EMR) consists of waves of the electromagnetic field, electromagnetic (EM) field, which propagate through space and carry momentum and electromagnetic radiant energy. It includes radio waves, microwaves, inf ...

emitting devices,

cosmetics Cosmetics are constituted mixtures of chemical compounds derived from either natural sources, or synthetically created ones. Cosmetics have various purposes. Those designed for personal care and skin care can be used to cleanse or protect ...

, animal foods and

veterinary drugs An animal drug (also veterinary drug) refers to a drug intended for use in the diagnosis, cure, mitigation, treatment, or prevention of disease in animals. Regulation United States The U.S. Food and Drug Administration (FDA) has the broad mandat ...

. In India, the

Narcotics Control Bureau The Narcotics Control Bureau ( NCB) is an Indian central law enforcement and intelligence agency under the Ministry of Home Affairs, Government of India. The agency is tasked with combating drug trafficking and the use of illegal substance ...

(abbr. NCB), an Indian federal law enforcement and

intelligence Intelligence has been defined in many ways: the capacity for abstraction, logic, understanding, self-awareness, learning, emotional knowledge, reasoning, planning, creativity, critical thinking, and problem-solving. More generally, it can b ...

agency under the

Ministry of Home Affairs An interior ministry (sometimes called a ministry of internal affairs or ministry of home affairs) is a government department that is responsible for internal affairs. Lists of current ministries of internal affairs Named "ministry" * Ministry ...

Government of India The Government of India (ISO: ; often abbreviated as GoI), known as the Union Government or Central Government but often simply as the Centre, is the national government of the Republic of India, a federal democracy located in South Asia, c ...

is tasked with combating

drug trafficking A drug is any chemical substance that causes a change in an organism's physiology or psychology when consumed. Drugs are typically distinguished from food and substances that provide nutritional support. Consumption of drugs can be via insuffla ...

and assisting international use of illegal substances under the provisions of Narcotic Drugs and Psychotropic Substances Act.

References

External links

DrugBank
a database of 13,400 drugs and 5,100 protein drug targets
"Drugs"
BBC Radio 4 discussion with Richard Davenport-Hines, Sadie Plant and Mike Jay (''In Our Time'', May 23, 2002) {{Authority control