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HLT 214 - Substance Use and Abuse - Textbook

Chapter 9. Hallucinogens

Learning Objectives

At the conclusion of this chapter, students will be able to:

  • List the names of common classic hallucinogens. 
  • Give examples of common dissociative drugs.
  • Describe the ways of use/routes of administration of hallucinogens.
  • Describe  how hallucinogens affect the brain and behavior.
  • Describe short term and long-term effects of hallucinogens.
  • Describe the ways of use/routes of administration of hallucinogens.



Humans have been ingesting mind-altering substances for thousands of years. Hallucinogenic plants have been used for religious rituals to induce states of detachment from reality and precipitate “visions” thought to provide supernatural access higher power in the spirit world. More recently, people use hallucinogenic drugs for more social or recreational purposes, including to have fun,  and cope with stress, or to enter into a more enlightened state of being. An example of a hallucinogenic substance is LSD. LSD is commonly known as "acid," but its scientific name lysergic acid diethylamide. The drug was first synthesized from a chemical called ergotamine in 1938 by Albert Hofmann, a chemist working for Sandoz Pharmaceutical.  LSD was popularized in the 1960s by individuals such as psychologist Timothy Leary, who encouraged American students to “turn on, tune in, and drop out.” This created an entire counterculture of drug abuse and spread the drug from America to the United Kingdom and the rest of Europe.  Use of LSD declined in the 1980s but picked up again in the 1990s. For a few years after 1998 LSD had become more widely used at dance clubs and all-night raves by older teens and young adults. Use dropped significantly since early 2000’s.1

Use and Abuse of Hallucinogens

Hallucinogens can be found in some plants and mushrooms (or their extracts) or can be man-made, and they are commonly divided into two broad categories: classic hallucinogens and dissociative drugs. 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 and psilocybin cause emotions to swing wildly and real-world sensations to appear unreal, sometimes frightening. Dissociative drugs like PCP, ketamine, DXM, and Salvia divinorum may make a user feel out of control and disconnected from their body and environment.2,3

Short-Term General Effects of Hallucinogens

Sensory Effects:

• Hallucinations, including seeing, hearing, touching, or smelling things in a distorted way or perceiving things that do not exist

• Intensified feelings and sensory experiences (brighter colors, sharper sounds)

• Mixed senses (“seeing” sounds or “hearing” colors)

• Changes in sense or perception of time (time goes by slowly)

Physical Effects:

• Increased energy and heart rate

• Nausea 

Long-Term Effects of Hallucinogens

Persistent psychosis

• Visual disturbances

• Disorganized thinking

• Paranoia • Mood disturbances

Hallucinogen Persisting Perception Disorder (HPPD)

• Hallucinations

• Other visual disturbances (such as seeing halos or trails attached to moving objects)

• Symptoms sometimes mistaken for neurological disorders (such as stroke or brain tumor)

How Do Hallucinogens Work?

Classic hallucinogens are thought to produce their perception-altering effects by acting on neural circuits in the brain that use the neurotransmitter serotonin. Specifically, some of their most prominent effects occur in the prefrontal cortex—an area involved in mood, cognition, and perception—as well as other regions important in regulating arousal and physiological responses to stress and panic.

How Do Dissociative Drugs Work?

Laboratory studies suggest that dissociative drugs, including PCP, ketamine, and DXM, cause their effects by disrupting the actions of the brain chemical glutamate at certain types of receptors—called N-methyl-D-aspartate (NMDA) receptors—on nerve cells throughout the brain. Glutamate plays a major role in cognition (including learning and memory), emotion, and the perception of pain (the latter via activation of pain-regulating cells outside of the brain). PCP also alters the actions of dopamine, a neurotransmitter responsible for the euphoria and “rush” associated with many abused drugs. Salvia divinorum works differently. While classified as a dissociative drug, salvia causes its effects by activating a specific type of opioid receptor (the kappa opioid receptor) on nerve cells. These receptors differ from those activated by the more commonly known opioids such as heroin and morphine.3

Chapter Review and Discussion Questions


  1. How do hallucinogens affect the brain?
  2. Describe the short term and long-term effects of the use of hallucinogens.
  3. Hallucinogen users refer to the experiences brought on by these drugs as "trips." Describe a “bad trip.”
  4. Describe the two broad categories of hallucinogens and give examples for each.
  5. What are club drugs? Describe them and give examples of club drugs.