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Drugs of Abuse

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On this page, we provide a brief and introductory description of drugs and their effects according to the following 6-part classification system (Inaba and Cohen, 1993):

  • Opiates and Opioids

  • Sedative-Hypnotics

  • Stimulants

  • Hallucinogens

  • Marijuana or Cannabis

  • Inhalants

Visitors should bear in mind that drug effects are not as simple to understand as might first appear from a brief description. Every drug's biochemical effect interacts with a person's psychological expectations for using the drug and the social setting within which the use occurs. For example, alcohol is a central nervous system depressant. However, alcohol use can be stimulating, quieting, or consciousness altering, depending upon the dose and the social setting within which alcohol is used.

Opiates (including opioids), sedatives, and most inhalants are "downers." Stimulants are "uppers." Marijuana and hallucinogens are best thought of as "all-arounders" because of their mixed effects. The following brief descriptions of these drug classes provide an introduction to the most common psychoactive drugs of abuse.

Opiates & Opioids

The term opioid refers to natural and synthetic substances with morphine-like activity. Opiate refers to a subclass of opioids consisting of alkaloid compounds extracted from opium, including morphine, codeine, and semisynthetic derivatives of the poppy plant. The term endorphin refers to another subclass of opioids consisting of endogenous peptides that produce pain relief, including enkephalins, dynorphins, and beta-endorphins. Opioids have analgesic and central nervous system (CNS) depressant effects, as well as the potential to cause euphoria. Morphine is the prototypical opioid. Heroin is a derivative of morphine and is the most commonly abused opioid. Opioid dependence or addiction is defined as continued use of opioids despite significant opioid-induced problems; these problems may be cognitive, behavioral, or physiological. Repeated drug use results in opioid tolerance (requiring escalating doses to achieve the same effect), withdrawal symptoms, and compulsive drug taking.

Opium is the crude substance derived from the opium poppy; it has been used by people since as early as 4000 BC. Morphine was purified from opium early in the nineteenth century and widely used for analgesia during the United States Civil War. Heroin and morphine were key ingredients in many patent medicines in North America during the late 1800s.

The popularity of heroin as a drug of abuse reached a peak in the 1960s, but declined somewhat during the 1970s and 1980s due to greater awareness of the risks of overdose and the increased popularity of cocaine. The chemical name for heroin is diacetylmorphine. Street names include dope, horse, smack, and tar.


Sedatives include alcohol, barbiturates, and an array of non-barbiturate drugs (e.g., benzodiazapines). Drugs from this class depress the central nervous system and can induce sleep. Often people use drugs from this class to provide relief from feelings of tension and anxiety. In an adequate dose, sedatives can cause slurring of speech and a staggered gait. Sedatives can produce a dangerous withdrawal syndrome (DTs).

Alcohol is the most commonly used sedative. People have used alcohol safely and enjoyably for thousands of years, and it continues to occupy an important place in many religious ceremonies and social celebrations. In addition, it now appears that moderate alcohol use can provide certain health benefits, particularly with regard to coronary heart disease. Yet, alcohol consumption is also associated with serious risks. Drinking too much alcohol is a significant cause of accidents and injuries and can lead to liver disease, certain types of stroke, abnormally high blood pressure (hypertension), various cancers, and birth defects, among other adverse effects. Thus, understanding the possible risks and benefits is essential in helping you make an informed decision about alcohol use and its potential effects on your health, safety, and well-being, as well as that of your family and community.


Stimulants or psychostimulant drugs are "uppers." These drugs have the ability to: (1) increase mental alertness and focus; (2) enhance physical energy; (3) cause excitation by influencing brain chemicals (e.g., noradrenalin, norepinephrine, dopamine); and (4) produce euphoria or a sense of well-being initially and at low dosages (Kauffman et al., 1984). Stimulant drugs that are used non-medically include nicotine, caffeine, cocaine and amphetamines. Stimulants can be natural, refined, or synthetic. When classifying drugs by their biological effects (as opposed to classification systems based on legal status), we observe that nicotine, caffeine, and cocaine represent refined forms of the tobacco leaf, coffee bean, and coca leaf, respectively. Chronic stimulant users may experience a wide range of shifting emotions, irritation, outbursts of anger, violent or assaultive behavior, paranoia, delusional thinking, visual and auditory hallucinations, or any combination of these symptoms.

Amphetamines and cocaine are the most prevalent stimulants abused. Cocaine is a short-acting local anesthetic with marked stimulant effects. Cocaine HCl is the most common form of cocaine used for illicit or therapeutic purposes. It is processed from the leaves of the coca plant. It is most commonly used by insufflation (snorting) but also can be injected intravenously. Alkaloid forms of cocaine can be made by different techniques to produce "crack," which is suitable for smoking and results in a very rapid attainment of high blood levels and sometimes extreme paranoid behavior. Amphetamines come in a variety of commercial and illicit preparations that can be used orally, intranasally, smoked, or injected. Methamphetamine is a more potent form of amphetamine used for therapeutic and illicit purposes. The free-based form of methamphetamine hydrochloride (HCl) is highly pure and smokable, and is known on the street as "ice."

"Designer drugs" are synthetic derivatives of federally controlled substances, created by slightly altering the molecular structure of existing drugs and produced illegally in clandestine laboratories for illicit use. There are at least six amphetamine designer drugs available on the illicit market today (Hoecker, 2003). The most popular of these is methylenedioxymethamphetamine (MDMA), known on the street as "Ecstasy." Most of these drugs have some psychoactive properties and cause visual disturbances, but are not true hallucinogens like lysergic acid diethylamide (LSD). MDMA may be associated with severe acute toxicity, including fulminant hyperthermia, seizures, disseminated intravascular coagulation, rhabdomyolysis, acute renal failure, and hepatotoxicity (Henry, J., et al, 1992). It may also cause acute rises in systolic and diastolic blood pressure, heart rate, and myocardial oxygen consumption (Lester, et al, 2000).

According to estimates by the National Institute on Drug Abuse (NIDA), only 10 to 15 percent of those who initially try stimulants (specifically cocaine) intranasally become abusers. No set of characteristics has been identified that predict whether a recreational user will become chemically dependent.


The most commonly used hallucinogens are lysergic acid diethylamide (LSD), mescaline, and psilocybin. Hallucinogen abuse dropped off precipitously in the mid and late 1970s and remained at low levels during the 1980s. Hallucinogenic drugs alter sensations and perceptions and tend to stimulate a shift in the perception of reality. These changes range from mild to wild. Sensation is the raw information from sensory organs that our nervous system sends to the brain. For example, when we see or hear something, receptor cells from our eyes or ears send a message to the brain. Perception is the result of how the brain assembles this sensory information into recognizable experiences.

Clinical features of hallucinogen intoxication include pupillary dilation, tachycardia, sweating, palpitations, blurred vision, tremors, and incoordination. Patients may also experience psychological symptoms such as anxiety, depression, paranoia, hallucinations, intensification of perception, impaired judgment, ideas of reference (getting messages from the television or radio), depersonalization ("I am not real"), derealization ("The environment is not real"), synesthesias ("See the sounds, taste the colors"), and impaired social or occupational functioning.

The quality of the LSD-induced psychedelic state, or "trip," is influenced by the mood and environment of the user at the time of induction (set and setting). A "bad trip" can be caused by fear, anxiety, or anger at the time the drug is taken. The most significant characteristic of a bad trip is fear; 99 percent of all bad trips can be handled without medication by a friend, nurse, aide, or physician. It may be difficult at times to distinguish between a bad trip and an acute psychotic reaction.

Marijuana (Cannabis)

The term "marijuana" refers to the dried material (leaves, stems, seeds) of the hemp plant, Cannabis sativa; this is the form used most commonly in the United States. The term "hashish" refers to dried resin made from hemp flowers. "Hash oil" is a liquid extracted from the plant material, and this form is the most potent. The active ingredient in all forms of marijuana is delta-9-tetrahydrocannabinol (THC) (Adams, 1942). The most common route of administration for marijuana is smoking, either as a rolled cigarette ("joint" or "blunt") or through a pipe ("bhong"). It can be taken orally, which results in a slower onset but longer duration of action. It is rarely used intravenously due to the risk of complications from injection of undissolved plant material. THC and other cannabinoids are rapidly absorbed from the lungs and bind to endogenous cannabinoid receptors in the central nervous system. This binding is responsible for the psychoactive properties that users seek (Weaver, 2003). Two endogenous cannabinoid receptors have been identified in the central nervous system (Onaivi, et al, 1996) (Stella, N., et al, 1997).

Marijuana is a psychostimulant that has properties of both stimulants and hallucinogens. Stimulants energize the central nervous system while hallucinogens can disorient sensory information and perception. In spite of marijuana's stimulating properties, marijuana users often report feeling more relaxed and less stimulated, though they also report stimulation of perceptual experiences. There are three species of marijuana-producing plants: Cannabis sativa, Cannabis indica and Cannabis ruderalis. Of these, the Cannabis sativa plant is the most psychoactive and the most popular. Drug users often grind up the leaves and flowers of Cannabis sativa into drinks or food; however, they are more likely to dry marijuana and smoke it. The pure resin from the plant, known as hashish, also can be smoked, eaten, or drunk. The coarse fibers of the plant known as hemp can be used for paper, clothing, rope, and other products. Marijuana that is taken orally (e.g., "hash brownies") takes about 30-60 minutes before users feel its effects. The delay in subjective effect is dependent upon what is in the user's stomach at the time of ingestion. Smoking marijuana stimulates psychoactive effects more rapidly, usually between 30 seconds to a few minutes. As with other drugs, the nature of the marijuana using experience depends upon the potency of the plant, the expectations of the user, and the social setting within which the drug is used.


Inhalants are toxic vapors that can be sniffed of "huffed." This form of drug abuse should be of special interest to middle school educators because these drugs are most likely to be abused by middle school aged students. Inhalants are cheap, act quickly upon the nervous system, and are easy to obtain. Inhalants are found readily in the household, and can be in gas or liquid form. The most common types of inhalants include: (1) organic solvents (e.g., gasoline, paints and glues) and organic sprays (e.g., hairspray, deodorants); (2) volatile nitrites such as amyl nitrite and room odorizers; and (3) anesthetics such as whip cream propellant, chloroform, or nitrous oxide. Inhalants are popular drugs for users seeking quick delirium, disorientation and intoxication.

The American Academy of Pediatrics encourages pediatricians to increase their awareness of the clinical features and complications of inhalant abuse and to promote education about the health hazards of inhalants to children, adolescents, parents, teachers, and vendors of volatile substances (American Academy of Pediatrics, 1996). In addition, the Massachusetts Department of Public Health has developed a suggested action plan for prevention of inhalant abuse (

References and Suggested Readings

Adams, R. Marijuana. Bulletin of the New York Academy of Medicine 1942; 18:705.

Inhalant abuse. American Academy of Pediatrics, Committee on Substance Abuse and Committee on Native American Child Health. Pediatrics 1996; 97:420.

The Columbia Electronic Encyclopedia The Columbia Electronic Encyclopedia Copyright 2003, Columbia University Press. Licensed from Lernout & Hauspie Speech Products N.V. All rights reserved.

Effective medical treatment of opiate addiction. National Consensus Development Panel on Effective Medical Treatment of Opiate Addiction. Journal of the American Medical Association 1998; 280:1936.

Grinspoon, L. & Bakalar, J.B. (1990). Drug abuse and dependence. The Harvard Medical School Mental Health Review Monograph, 1-26.

Henry, JA, Jeffreys, KJ, Dawling, S. Toxicity and deaths from 3,4-methylenedioxymethamphetamine ("ecstasy"). Lancet 1992; 340:384.

Hoecker, CC. Designer drugs in adults. In: UpToDate, Rose, BD (Ed), UpToDate, Wellesley, MA, 2004.

Hyman, S. E. (1994). Why does the brain prefer opium to broccoli? Harvard Review of Psychiatry, 2(1), 43-46.

Inaba, D.S. & Cohen, W.E. (1993). Uppers, downers, all-arounders: Physical and mental effects of psychoactive drugs (2nd edition). Ashland: CNS Productions.

Kauffman, J.F., Shaffer, H.J., & Burglass, M.E. (1984). The biological basics: drugs and their effects. In T.Bratter, S. Davidson & G. Forrest (Eds.)Current treatment of substance abuse and alcoholism. New York: MacMillan Publishing.

Lester, SJ, Baggott, M, Welm, S, et al. Cardiovascular effects of 3,4-methylenedioxymethamphetamine. A double-blind, placebo-controlled trial. Ann Intern Med 2000; 133:969.

Onaivi, ES, Chakrabarti, A, Chaudhuri, G. Cannabinoid receptor genes. Prog Neurobiol 1996; 48:275.

Stella, N, Schweitzer, P, Piomelli, D. A second endogenous cannabinoid that modulates long-term potentiation. Nature 1997; 388:773.

Weaver, M. Marijuana. In: UpToDate, Rose, BD (Ed), UpToDate, Wellesley, MA, 2004.

Weil, A. & Rosen, W. (1993). From chocolate to morphine: Everything you need to know about mind-altering drugs (Rev. Ed.). Boston: Houghton Mifflin Company.

Winger, G., Hofmann, F.G., & Woods, J.H. (1992). A handbook on drug and alcohol abuse: The biomedical aspects (3rd edition). New York: Oxford University Press.



Division on Addiction. All Rights Reserved. Last Updated:  January 23, 2014