Long-Term Effects of Hallucinogens See page 5. Research Report Series from the director: Hallucinogens and dissociative drugs — which have street names like acid, angel dust, and vitamin K — distort the way a user perceives time, motion, colors, sounds, and self. These drugs can disrupt a person’s ability to think and communicate rationally, or even to recognize reality, sometimes resulting in bizarre or dangerous behavior. Hallucinogens such as LSD, psilocybin, HALLUCINOGENS AND peyote, DMT, and ayahuasca cause emotions to swing wildly and real-world DISSOCIATIVE DRUGS sensations to appear unreal, sometimes frightening. Dissociative drugs like PCP, ketamine, dextromethorphan, and Salvia Including LSD, Psilocybin, Peyote, DMT, Ayahuasca, divinorum may make a user feel out of PCP, Ketamine, Dextromethorphan, and Salvia control and disconnected from their body and environment. What Are In addition to their short-term effects on perception and mood, hallucinogenic Hallucinogens and drugs are associated with psychotic- Dissociative Drugs? like episodes that can occur long after a person has taken the drug, and dissociative drugs can cause respiratory Hallucinogens are a class of drugs that cause hallucinations—profound distortions depression, heart rate abnormalities, and in a person’s perceptions of reality. Hallucinogens can be found in some plants and a withdrawal syndrome. The good news is mushrooms (or their extracts) or can be man-made, and they are commonly divided that use of hallucinogenic and dissociative into two broad categories: classic hallucinogens (such as LSD) and dissociative drugs (such drugs among U.S. high school students, as PCP). When under the influence of either type of drug, people often report rapid, intense in general, has remained relatively low in emotional swings and seeing images, hearing sounds, and feeling sensations that seem real recent years. However, the introduction but are not. of new hallucinogenic and dissociative While the exact mechanisms by which hallucinogens and dissociative drugs cause drugs is of particular concern. their effects are not yet clearly understood, research suggests that they work at least partially by temporarily disrupting communication between neurotransmitter systems throughout NIDA research is developing a clearer the brain and spinal cord that regulate mood, sensory perception, sleep, hunger, body picture of the dangers of hallucinogenic and dissociative drugs. We have compiled temperature, sexual behavior, and muscle control. the scientific information in this report to inform readers and hopefully prevent the use of these drugs. Nora D. Volkow, M.D. Director National Institute on Drug Abuse Psilocybin mushrooms, LSD, and Salvia divinorum are commonly used hallucinogenic and dissociative compounds. U.S. Department of Health and Human Services | National Institutes of Health Common Hallucinogens and Research Report Series Dissociative Drugs Classic Hallucinogens* LSD (d-lysergic acid Peyote (Mescaline)— prevents the normal breakdown of diethylamide)—also also known as buttons, DMT in the digestive tract. Ayahuasca known as acid, blotter, cactus, and mesc— tea has traditionally been used for healing doses, hits, microdots, is a small, spineless and religious purposes in indigenous sugar cubes, trips, tabs, or window cactus with mescaline as its main South American cultures, mainly in the panes—is one of the most potent mood- ingredient. It has been used by Amazon region. and perception-altering hallucinogenic natives in northern Mexico and the drugs. It is a clear or white, odorless, southwestern United States as a part Dissociative Drugs water-soluble material synthesized from of religious ceremonies. The top, or lysergic acid, a compound derived from “crown,” of the peyote cactus has PCP (Phencyclidine)—also a rye fungus. LSD is initially produced disc-shaped buttons that are cut out, known as ozone, rocket fuel, in crystalline form, which can then dried, and usually chewed or soaked love boat, hog, embalming be used to produce tablets known as in water to produce an intoxicating fluid, or superweed—was “microdots” or thin squares of gelatin liquid. Because the extract is so bitter, originally developed in the 1950s as a called “window panes.” It can also be some users prepare a tea by boiling general anesthetic for surgery. While it can diluted with water or alcohol and sold the plant for several hours. Mescaline be found in a variety of forms, including in liquid form. The most common form, can also be produced through tablets or capsules, it is usually sold as however, is LSD-soaked paper punched chemical synthesis. a liquid or powder. PCP can be snorted, into small individual squares, known smoked, injected, or swallowed. It is DMT (Dimeth- as “blotters.” sometimes smoked after being sprinkled yltryptamine)—also on marijuana, tobacco, or parsley. Psilocybin known as Dimitri—is a (4-phosphoryloxy- powerful hallucinogenic Ketamine—also known N, N-dimethyl- chemical found naturally occurring in as K, Special K, or cat tryptamine)—also some Amazonian plant species (see Valium—is a dissociative known as magic mushrooms, shrooms, “Ayahuasca”) and also synthesized in currently used as an boomers, or little smoke—is extracted the laboratory. Synthetic DMT usually anesthetic for humans as well as animals. from certain types of mushrooms found takes the form of a white crystalline Much of the ketamine sold on the street in tropical and subtropical regions of powder and is typically vaporized or has been diverted from veterinary South America, Mexico, and the United smoked in a pipe. offices. Although it is manufactured States. In the past, psilocybin was Ayahuasca—also as an injectable liquid, ketamine is ingested during religious ceremonies by known as hoasca, generally evaporated to form a powder indigenous cultures from Mexico and aya, and yagé—is a that is snorted or compressed into pills for Central America. Psilocybin can either hallucinogenic brew illicit use. Because ketamine is odorless be dried or fresh and eaten raw, mixed made from one of several Amazonian and tasteless and has amnesia-inducing with food, or brewed into a tea, and plants containing DMT (the primary properties, it is sometimes added to drinks produces similar effects to LSD. psychoactive ingredient) along with a to facilitate sexual assault. vine containing a natural alkaloid that *In this report, the term “hallucinogen” will refer to the classic hallucinogenic drugs LSD and Psilocybin. 2 NIDA Research Report Series Past-Year Use of Hallucinogenic and Dissociative DXM (Dextromethorphan)— also known as robo—is Drugs Among 12th-Grade Students a cough suppressant and 8.0 expectorant ingredient in Salvia some over-the-counter (OTC) cold and %) 6.0 LSD cough medications that are often abused h ( PCP nt by adolescents and young adults. The o M most common sources of abused DXM st a 4.0 P are “extra-strength” cough syrup, which e h typically contains around 15 milligrams n t e i of DXM per teaspoon, and pills and s 2.0 U gel capsules, which typically contain 15 milligrams of DXM per pill. OTC 0.0 medications that contain DXM often also 2007 2008 2009 2010 2011 2012 2013 2014 contain antihistamines and decongestants. Source: Monitoring the Future National Survey Results on Drug Use, 2014 Overview Salvia divinorum—also known as diviner’s sage, While regular use of hallucinogenic Why Do Maria Pastora, Sally-D, and dissociative drugs in general has People Take or magic mint—is a remained relatively low in recent years, psychoactive plant common to southern one study reported that the United States Hallucinogenic Mexico and Central and South America. ranks first among 36 nations in the or Dissociative Salvia is typically ingested by chewing proportion of high school students ever Drugs? fresh leaves or by drinking their extracted using LSD or other hallucinogens in juices. The dried leaves of salvia can also their lifetime (6 percent versus 2 percent Hallucinogenic and dissociative drugs be smoked or vaporized and inhaled. in Europe) (Hibell, 2012). have been used for a variety of reasons Additionally, tourism to the Amazon (Bogenschutz, 2012; Bonson, 2001). for the purpose of using ayahuasca has Historically, hallucinogenic plants have How Widespread become increasingly popular among been used for religious rituals to induce Is the Abuse of Americans and Europeans in recent states of detachment from reality and Hallucinogens and years, and ayahuasca use has also been precipitate “visions” thought to provide reported in major cities in Brazil and mystical insight or enable contact Dissociative Drugs? abroad (Barbosa, 2012; McKenna, with a spirit world or “higher power.” According to the 2013 National Survey on 2004). Although DMT is a schedule More recently, people report using Drug Use and Health, 229,000 Americans I drug, plants containing DMT are hallucinogenic drugs for more social or ages 12 and older reported current (past- not scheduled, and there is ambiguity recreational purposes, including to have month) use of LSD and 33,000 reported over ayahuasca’s legal status in the fun, help them deal with stress, or enable current use of PCP (Substance Abuse and United States (McKenna, 2004). Two them to enter into what they perceive Mental Health Services Administration, U.S. Brazilian churches have obtained as a more enlightened sense of thinking 2013). Among high school seniors, salvia permission to import and use these or being. Hallucinogens have also been was significantly more popular than plants in their ceremonies. investigated as therapeutic agents to treat diseases associated with perceptual LSD or PCP when it was added to the distortions, such as schizophrenia, Monitoring the Future survey in 2009. obsessive-compulsive disorder, bipolar Past-year use was reported to be 5.9 disorder, and dementia. Anecdotal reports percent for salvia, 2.7 percent for LSD, and small studies have suggested that and 1.3 percent for PCP. Fortunately, rates ayahuasca may be a potential treatment have dropped significantly for saliva—to for substance use disorders and other 1.8 percent in 2014—with LSD and PCP mental health issues, but no large- use dropping slightly (Johnston, 2014). scale research has verified its efficacy (Barbosa, 2012). 3 NIDA Research Report Series are often unpredictable and may vary How Do with the amount ingested and the Hallucinogens user’s personality, mood, expectations, (LSD, Psilocybin, and surroundings. The effects of hallucinogens like LSD can be described Peyote, DMT, and as drug-induced psychosis—distortion Ayahuasca) Affect or disorganization of a person’s capacity the Brain and Body? to recognize reality, think rationally, or communicate with others. Users How Do Hallucinogens refer to LSD and other hallucinogenic Work? experiences as “trips” and to acute adverse or unpleasant experiences as Classic hallucinogens are thought to Short-Term “bad trips.” On some trips, users produce their perception-altering effects General Effects experience sensations that are by acting on neural circuits in the brain of Hallucinogens enjoyable and mentally stimulating that use the neurotransmitter serotonin and that produce a sense of heightened Sensory Effects (Passie, 2008; Nichols, 2004; Schindler, understanding. Bad trips, however, • Hallucinations, including 2012; Lee, 2012). Specifically, some of seeing, hearing, touching, or include terrifying thoughts and their most prominent effects occur in smelling things in a distorted the prefrontal cortex—an area involved nightmarish feelings of anxiety and way or perceiving things that despair that include fears do not exist in mood, cognition, and perception—as of losing control, insanity, or death. • Intensified feelings and well as other regions important in sensory experiences (brighter Like LSD and psilocybin, DMT regulating arousal and physiological colors, sharper sounds) produces its effects through action at responses to stress and panic. • Mixed senses (“seeing” serotonin (5-HT) receptors in the brain What Are the Short- sounds or “hearing” colors) (Strassman, 1996). Some research has Term Effects of • Changes in sense or suggested that DMT occurs naturally perception of time (time Hallucinogens? in the human brain in small quantities, goes by slowly) Ingesting hallucinogenic drugs can cause leading to the hypothesis that release of Physical Effects users to see images, hear sounds, and endogenous DMT may be involved in • Increased energy and feel sensations that seem real but do not reports of alien abductions, spontaneous heart rate exist. Their effects typically begin within mystical experiences, and near- • Nausea 20 to 90 minutes of ingestion and can death experiences, but this remains last as long as 12 hours. Experiences controversial (Barker, 2012). Specific short-term effects of LSD, psilocybin, peyote, DMT, and ayahuasca include: LSD Psilocybin DMT • Increased blood pressure, heart • Feelings of relaxation (similar to • Increased heart rate rate, and body temperature effects of low doses of marijuana) • Agitation • Dizziness and sleeplessness • Nervousness, paranoia, and • Hallucinations frequently involving • Loss of appetite, dry mouth, panic reactions radically altered environments as and sweating • Introspective/spiritual experiences well as body and spatial distortions • Numbness, weakness, and tremors • Misidentification of poisonousmushrooms Ayahuasca • Impulsiveness and rapid emotional resembling psilocybin could lead to • Increased blood pressure shifts that can range from fear to unintentional, potentially fatal poisoning • Severe vomiting (induced by the tea) euphoria, with transitions so rapid Peyote • Profoundly altered state of awareness that the user may seem to experience • Increased body temperature and and perceptions of otherworldly imagery several emotions simultaneously heart rate • Uncoordinated movements (ataxia) • Profound sweating • Flushing 4 NIDA Research Report Series What Are the Long- especially among those using the brew Term Effects of for religious activities. Hallucinogens? Overall, two long-term effects— persistent psychosis and HPPD—have LSD users quickly develop a high degree been associated with use of classic of tolerance to the drug’s effects, such hallucinogens (see sidebar). Although that repeated use requires increasingly occurrence of either is rare, it is also larger doses to produce similar effects. unpredictable and may happen more Use of hallucinogenic drugs also often than previously thought, and produces tolerance to other drugs in this sometimes both conditions occur class, including psilocybin and peyote. together. While the exact causes are not Use of classic hallucinogens does not, known, both conditions are more often however, produce tolerance to drugs that Long-Term Effects seen in individuals with a history of do not act directly on the same brain of Hallucinogens psychological problems but can happen cell receptors. In other words, there is to anyone, even after a single exposure. Persistent psychosis no cross-tolerance to drugs that act on There is no established treatment for • Visual disturbances other neurotransmitter systems, such HPPD, in which flashbacks may occur • Disorganized thinking as marijuana, amphetamines, or PCP, spontaneously and repeatedly although • Paranoia among others. Furthermore, tolerance for less intensely than their initial occurrence. • Mood disturbances hallucinogenic drugs is short-lived—it is Some antidepressant and antipsychotic lost if the user stops taking the drugs for Hallucinogen Persisting drugs can be prescribed to help improve several days—and physical withdrawal Perception Disorder (HPPD) mood and treat psychoses, however. symptoms are not typically experienced • Hallucinations Psychotherapy may also help patients when chronic use is stopped. • Other visual disturbances cope with fear or confusion associated The long-term residual (such as seeing halos or trails with visual disturbances or other psychological and cognitive effects attached to moving objects) consequences of long-term LSD use. of peyote remain poorly understood. • Symptoms sometimes More research on the causes, incidence, mistaken for neurological Although one study found no evidence and long-term effects of both disorders is disorders (such as stroke of psychological or cognitive deficits being conducted. or brain tumor) among Native Americans who use peyote regularly in a religious setting, those What Are the findings may not generalize to those who Effects of Common repeatedly abuse the drug for recreational Dissociative role in cognition (including learning and purposes (Halpern, 2005). Peyote users may also experience hallucinogen Drugs on the memory), emotion, and the perception of pain (the latter via activation of pain- persisting perception disorder (HPPD)— Brain and Body? regulating cells outside of the brain). also often referred to as flashbacks. The PCP also alters the actions of dopamine, active ingredient mescaline has also been How Do Dissociative a neurotransmitter responsible for the associated, in at least one report, to Drugs Work? euphoria and “rush” associated with fetal abnormalities (Gilmore, 2001). Laboratory studies suggest that many abused drugs. Long-term effects of DMT use dissociative drugs, including PCP, Salvia divinorum works differently. and abuse and addiction liability are ketamine, and DXM, cause their effects While classified as a dissociative drug, currently unknown. Unlike most other by disrupting the actions of the brain salvia causes its effects by activating hallucinogens, DMT does not appear to chemical glutamate at certain types of the kappa opioid receptor on nerve induce tolerance (Winstock, 2013). receptors—called N-methyl-D-aspartate cells (Cunningham, 2011; MacLean, As with some other hallucinogens, (NMDA) receptors—on nerve cells 2013). These receptors differ from those there is little information to suggest throughout the brain (Morgan, 2012; activated by the more commonly known that ayahuasca use creates lasting Morris, 2005). Glutamate plays a major opioids such as heroin and morphine. physiological or neurological deficits, 5 NIDA Research Report Series What Are the Short-Term Effects of Dissociative Drugs? Dissociative drugs can produce visual and auditory distortions and a sense of floating and dissociation (feeling detached from reality) in users. Use of dissociative drugs can also cause anxiety, memory loss, and impaired motor function, including body tremors and numbness. These effects, which depend on the amount of the drug taken, are also unpredictable—typically beginning within minutes of ingestion and lasting for several hours, although some users report feeling the drug’s effects for days. See text box for general effects of dissociative drugs. General Common Effects of Dissociative Drugs Low to Moderate Doses High Doses Numbness Hallucinations Disorientation, confusion, and loss of coordination Memory loss Dizziness, nausea, vomiting Physical distress, including dangerous changes in blood pressure, heart rate, respiration, and body temperature Changes in sensory perceptions (such as sight, sound, shapes, time, and body image) Marked psychological distress, including feelings of extreme panic, fear, anxiety, paranoia, invulnerability, exaggerated Hallucinations strength, and aggression Feelings of detachment from self and environment Use with high doses of alcohol or other central nervous system depressants can lead to respiratory distress or Increase in blood pressure, heart rate, respiration, arrest, resulting in death and body temperature In addition to these general experiencing terrifying feelings of 15 to 30 milligrams), can lead to effects, different dissociative drugs almost complete sensory detachment serious side effects when abused. can produce a variety of distinct and likened to a near-death experience For example, use of DXM at doses dangerous effects. For example, at (called a “K-hole,” similar to a bad from 200 to 1,500 milligrams can moderate to high doses, PCP can LSD trip). Salvia users report intense produce dissociative effects similar cause a user to have seizures or but short-lived effects—up to 30 to PCP and ketamine and increase severe muscle contractions, become minutes—including emotional mood the risk of serious central nervous aggressive or violent, or even swings ranging from sadness to system and cardiovascular effects experience psychotic symptoms uncontrolled laughter. such as respiratory distress, similar to schizophrenia. At moderate DXM, which is safe and seizures, and increased heart rate to high doses, ketamine can cause effective as a cough suppressant from the antihistamines found in sedation, immobility, and amnesia. At and expectorant when used at cough medicines. high doses, ketamine users also report recommended doses (typically What Are the Long-Term Effects of Dissociative Drugs? While the long-term use of most dissociative drugs has not been investigated systematically, research shows that repeated use of PCP can lead to tolerance and the development of a substance use disorder that includes a withdrawal syndrome (including craving for the drug, headaches, and sweating) when drug use is stopped. Other effects of long-term PCP use include persistent speech difficulties, memory loss, depression, suicidal thoughts, anxiety, and social withdrawal that may persist for a year or more after chronic use stops. 6 NIDA Research Report Series Glossary References Central Nervous System: The brain Barbosa PC, Mizumoto S, Bogenschutz MacLean KA, Johnson MW, Reissig CJ, and spinal cord. MP, Strassman RJ. Health status of Prisinzano TE, Griffiths RR. Dose-related ayahuasca users. Drug Test Anal. 2012; effects of salvinorin A in humans: Cerebral cortex: The region of the 4(7-8):601-609. dissociative, hallucinogenic, and brain responsible for cognitive memory effects. Psychopharmacology functions including reasoning, mood, Barker SA, McIlhenny EH, (Berl). 2013;226(2):381-392. and perception of stimuli. Strassman R. A critical review of reportsof endogenous psychedelic McKenna, DJ. Clinical investigations of Dissociative: a type of compound, N, N-dimethyltryptamines in humans: the therapeutic potential of ayahuasca: such as phencyclidine or ketamine, 1955-2010. Drug Test Anal. 2012; rationale and regulatory challenges. that produces an anesthetic effect Jul-Aug;4(7-8):617-35. Pharmacol Ther. 2004;102(2):111-129. characterized by a feeling of being detached from the physical self. Bogenschutz MP, Pommy JM. Morgan CJ, Curran HV, Independent Therapeutic mechanisms of classic Scientific Committee on Drugs. DXM: A common street name for hallucinogens in the treatment of Ketamine use: a review. Addiction. dextromethorphan. addictions: from indirect evidence to 2012;107(1):27-38. testable hypotheses. Drug Test Anal. Flashback: A sudden but temporary 2012;4(7-8):543-555. Morris BJ, Cochran SM, and Pratt JA. recurrence of aspects of a drug PCP: from pharmacology to modelling experience (including sights, sounds, Bonson KR. Hallucinogenic drugs. schizophrenia. Curr Opin Pharmacol. and feelings) that may occur days, In: Encyclopedia of Life Sciences. 2005;5(1):101-106. weeks, or even more than a year after United Kingdom: Nature Publishing hallucinogenic drug use. Group; 2001. Nichols DE. Hallucinogens. Pharmacol Ther. 2004; 101(2):131-181. Glutamate: An excitatory Bouso JC, González D, Fondevila S, neurotransmitter found throughout et al. Personality, psychopathology, Passie T, Halpern JH, Stichtenoth the brain that influences the reward life attitudes and neuropsychological DO, Emrich HM, Hintzen A. The system and is involved in learning performance among ritual users of pharmacology of lysergic acid and memory, among other functions. Ayahuasca: a longitudinal study. PLoS diethylamide: a review. CNS One. 2012;7(8). Neurosci Ther. 2008;14(4):295-314. Hallucinogen: A drug that produces hallucinations—distortions in Cunningham CW, Rothman RB, Schindler EA, Dave KD, Smolock EM, perception of sights and sounds—and Prisinzano TE. Neuropharmacology of Aloyo VJ, Harvey JA. Serotonergic disturbances in emotion, judgment, the naturally occurring kappa-opioid and dopaminergic distinctions in and memory. hallucinogen salvinorin A. Pharmacol the behavioral pharmacology of Rev. 2011;63(2):316-347. (+/-)-1-(2,5-dimethoxy-4-iodophenyl)-2- HPPD: Hallucinogen persisting aminopropane (DOI) and lysergic acid perception disorder; the spontaneous Gilmore HT. Peyote use diethylamide (LSD). Pharmacol Biochem and sometimes continuous recurrence during pregnancy. S D J Med. Behav. 2012;101(1): 69-76. of perceptual effects of LSD long after 2001;54(1):27-29. an individual has ingested the drug. Strassman RJ. Human Halpern JH, Sherwood AR, Hudson psychopharmacology of N,N- Kappa opioid receptor: A receptor on JI, Yurgelun-Todd D, Pope HG Jr. dimethyltryptamine. Behav Brain Res. nerve cells that is activated by certain Psychological and cognitive effects 1996;73(1-2):121-124. opioid-like compounds produced in of long-term peyote use among the body. These receptors differ from Native Americans. Biol Psychiatry. Substance Abuse and Mental Health those activated by the more commonly 2005;58(8):624-631. Services Administration. Results from known opioids, such as heroin and the 2013 National Survey on Drug morphine. Hibell B, Guttormsson U, Ahlström S, et Use and Health: Summary of National al. The 2011 ESPAD Report: Substance Findings. Rockville, MD: Substance Neurotransmitter: A chemical Use Among Students in 36 European Abuse and Mental Health Services compound that acts as a messenger Countries. Stockholm, Sweden: The Administration; 2014. HHS Publication to carry signals from one nerve cell Swedish Council for Information on No. (SMA) 14-4887. NSDUH Series to another. Alcohol and Other Drugs (CAN); 2012. H-49. NMDA receptors: N-methyl-D-aspartate Johnston LD, O’Malley PM, Bachman Winstock AR, Kaar S, Borschmann receptors, a type of glutamate receptor JG, Schulenberg JE. Monitoring the R. Dimethyltryptamine (DMT): that is important for learning and Future national results on drug use: prevalence, user characteristics and memory; it is the target of drugs such 1975-2014. Overview of key findings abuse liability in a large global sample. as PCP and ketamine. on Adolescent Drug Use. Ann Arbor, J Psychopharmacol. 2014;28(1):49-54. MI: Institute for Social Research, The Persistent psychosis: Unpredictable University of Michigan; 2014. and long-lasting visual disturbances, dramatic mood swings, and Lee HM, and Roth BL. Hallucinogen hallucinations experienced by some actions on human brain revealed. LSD users after they have discontinued Proc Natl Acad Sci U S A. 2012; use of the drug. 109(6):1820-1821. Serotonin: A neurotransmitter involved in a broad range of effects on perception, movement, and emotions. Serotonin and its receptors are the targets of most hallucinogens. 7 NIDA Research Report Series Where can I get further information about hallucinogens? To learn more about hallucinogens NIDA’s website includes: For Physician Information and other drugs of abuse, • Information on drugs of abuse visit the NIDA website at and related health consequences www.drugabuse.gov or www.drugabuse.gov/nidamed contact the DrugPubs Research • NIDA publications, news, Dissemination Center at and events Other Websites 877-NIDA-NIH (877-643-2644; • Resources for health care Information on hallucingens TTY/TDD: 240-645-0228). professionals, educators, and dissociative drugs is also available through: and patients and families • Funding information (including • Substance Abuse and Mental program announcements and Health Services Administration: deadlines) www.samhsa.gov • International activities • Drug Enforcement Administration: • Links to related websites www.deadiversion.usdoj.gov (access to websites of many • Monitoring the Future: other organizations in the field) www.monitoringthefuture.org/ • Information in Spanish (en español) • The Partnership at Drug Free.org: NIDA Websites and Webpages www.drugfree.org/drug-guide www.drugabuse.gov www.teens.drugabuse.gov www.easyread.drugabuse.gov www.drugabuse.gov/drugs-abuse/ hallucinogens www.drugabuse.gov/publications/ term/160/DrugFacts www.hiv.drugabuse.gov/ www.researchstudies.drugabuse.gov/ www.irp.drugabuse.gov/ NIH Publication Number 15-4209 • Revised February 2015 This publication is in the public domain and may be used or reproduced in its entirety without permission from NIDA. Citation of the source is appreciated. 8 NIDA Research Report Series