Hallucinogens and Drug Abuse

Hallucinogens represent a class of drugs with psychoactive effects that produce significant changes in a person’s thinking processes (cognition) and a significant alteration of perceptual experiences. Perceptions refer to the subjective interpretation of environmental stimulation. Stimulation occurs as a result of energy being transmitted to the sensory areas in the brain via a number of sensory organs in the body, and perception refers to the subjective interpretation of analyzing this sensory stimulation.


effects of hallucinogens on the brain

Perception of environmental stimuli is altered in individuals who use hallucinogens. The National Institute on Drug Abuse (NIDA) lists a number of different types of hallucinogenic drugs. Drugs like marijuana (cannabis products) are often considered to be hallucinogenic drugs by lay individuals; however, the perceptual distortions produced by drugs like cannabis are not as severe and extreme as the alterations of perception that are produced by drugs in the hallucinogenic class.

Many different types of drugs produce the perception that one’s senses are enhanced, and this is also a common feature of hallucinogens. However, hallucinogenic drugs will typically produce hallucinations, or alterations of perception that do not exist in reality. For instance, the hallucinogen LSD will often produce visual and auditory hallucinations, such as seeing or hearing things that do not really exist. Hallucinogens can also produce other types of hallucinations, such as tactile hallucinations and olfactory hallucinations.

Many hallucinogenic drugs produce synesthesias, the perception that one’s senses are mixed. Often, individuals under the influence of these drugs may believe that they can see sounds, hear colors, etc. In addition, hallucinogenic drugs often produce significant distortions of one’s perception of time, space, and other aspects of reality, such as perception of the self or the nature of the world. These distortions are sometimes referred to as dissociative effects. Many advocates of the use of hallucinogenic drugs claim that these drugs expand one’s consciousness, and certain hallucinogenic drugs are used by specific religious sects for this experience. In some instances, the use of these substances by certain groups of individuals, such as Native Americans, is legal whereas the possession of these substances is not legal for others (e.g., the legal use of peyote for some groups).

Outside of specific groups being allowed to legally use certain substances in religious ceremonies, the classification of these substances by the United States Drug Enforcement Administration (DEA) indicates that the federal government assumes that most hallucinogens do not have any medicinal utility and are drugs that have a high risk to be abused and to result in psychological or physical dependence; the DEA generally classifies hallucinogens as Schedule I controlled substances. In spite of this classification, several hallucinogens have empirical evidence that they may indeed have medicinal uses (e.g., the use of LSD in the treatment of anxiety and other psychological issues).

Who Abuses Hallucinogenic Drugs?

According to the latest data collected by the Substance Abuse and Mental Health Services Administration (SAMHSA), an estimated 1.2 million individuals over the age of 12 years old reported using hallucinogenic drugs in 2015. SAMHSA combines all hallucinogens into one singular category. The breakdown of hallucinogen use in the United States by age group follows:

  • About 121,000 adolescents ages 12-17 years old reported being current users of hallucinogens in 2015.
  • Approximately 636,000 individuals 18-25 years old reported being current users of hallucinogens in 2015.
  • About 482,000 individuals over the age of 25 reported being current users of hallucinogens in 2015.
  • These figures suggest that nearly two-thirds of individuals reporting current hallucinogenic drug use are under the age of 26.

The mechanism of action for hallucinogenic drugs includes a number of different neurotransmitters, but most of the drugs have a significant effect on the neurotransmitter serotonin. The major organizations that investigate and track substance use/abuse in the United States, such as NIDA and SAMHSA, typically refer to the classical distinction of hallucinogenic drugs as falling into one of two broad subcategories: classic hallucinogenic drugs and dissociative hallucinogenic drugs. These subcategories divide hallucinogens by their primary effects.

More On Hallucinogens and Abuse

  • Risks of Mushroom Abuse and Its Effects on the Body
  • Mixing Mescaline and Alcohol: What Are the Risks?
  • What Is Mescaline, and What Are the Effects of Use?
  • Hallucinogens and the Effects on the Body


Drugs in the subcategory of classic hallucinogens are more likely to produce enhanced sensory abilities, alterations in one’s sense of the passage of time (most often, as time passing significantly more slowly), alterations in the perception of space (objects appearing larger or smaller), and the experience of hallucinations (most often, visual and auditory hallucinations). This class of hallucinogenic drugs does not typically produce significant dissociative effects, although in some individuals, these experiences may occur. There are several different classic hallucinogenic drugs that are familiar to most people.


Lysergic acid diethylamide (LSD) is perhaps the most well-known hallucinogenic drug. It is a synthetic drug that was developed in the 1930s in an effort to find medicines that could assist in childbirth. LSD had no utility for this effect, and its hallucinogenic effects were discovered by accident when the researcher who developed it decided to investigate any other potential uses it may have several years after its original formulation. The researcher accidentally ingested some of the drug and began to experience hallucinations. He later tested the drug on his colleagues and got similar results. LSD was considered to have significant medical uses for the treatment of individuals with psychiatric disorders. The drug became a significant part of the countercultural movement in the 1960s and 1970s, and it was propagated as a mind-expanding substance; however, it eventually lost favor, and the drug was banned and classified as a Schedule I controlled substance by the DEA.

LSD is a very potent substance. Users take very small doses that are typically ingested orally in pill form or as a liquid form that is placed on ingestible paper. The most common doses that individuals use are 100-200 micromilligrams, but the effects of LSD are quite long-lasting and may continue for 10-12 hours even in these small doses. The effects of taking LSD include:

  • Euphoria
  • An intensification of emotions
  • Distortions of the passage of time
  • A heightened perception of senses (e.g., colors seem brighter, sounds seem more acute, etc.)
  • Visual hallucinations or hallucinations of other sensory modalities

The subjective effects of LSD are often related to the particular situation in which the drug is used. For instance, an individual who is depressed or nervous may experience extreme depression or even panic attacks; an individual who is uncertain about the drug or has certain fears regarding losing control may feel hopeless and out of control; a person who is happy may begin to feel even happier, etc.

Interestingly, the evidence that high doses of LSD can result in fatalities is scant, and the vast majority of fatalities that are associated with LSD use indicate that these individuals also used other dangerous drugs in combination with LSD. Nonetheless, there are some significant risks to LSD that include the potential for engaging in risky or even self-harming behaviors as a result of a loss of reality, having “bad trips” that can be extremely distressing, and the development of a specific substance-related disorder known as hallucinogen persisting perception disorder. This disorder consists of a number of “flashbacks” that are similar to the effects of being on LSD when the individual has not taken the drug. This disorder may also appear in individuals who use other hallucinogenic drugs, but it is more common with LSD use. A very small proportion of individuals develop this disorder, and its treatment is based on the specific symptoms experienced.

Psilocybin Mushrooms

The hallucinogenic substance that is contained in a number of different types of mushrooms is psilocybin (4-phosphoryloxy-N, N-dimethyltryptamine). These mushrooms are commonly referred to as “psychedelic mushrooms” or “magic mushrooms,” and they are often grown in areas of Central and South America or in the southern portions of the United States. The mushrooms are most often dried and eaten, but in some cases, they may be ground up and used in beverages. Use of psilocybin typically produces:

  • Mild dissociative effects
  • Feelings of euphoria
  • Dilated pupils
  • Accelerated heart rate
  • Increased blood pressure
  • Tremors or shakiness
  • Distortions in the passage of time
  • Issues with physical coordination
  • Visual hallucinations (can occur across all senses)


Mescaline is a substance that can be naturally found in the cactus peyote that grows in areas of Central America and the United States. Mescaline can also be produced synthetically. Peyote is typically dried and chewed, or used in beverages; in some cases, it can even be dried and smoked). Artificially manufactured mescaline is often taken in the form of pills or as a liquid.

Certain Native American religious sects are still allowed to legally use peyote in their religious services in the US. Despite its classification by the DEA, there is little evidence to indicate that taking high doses of peyote can result in fatalities or other serious issues, although as with any hallucinogenic drug, issues can occur due to poor judgment, depression and suicidality, and accidents while under the influence of the drug.

The effects of taking mescaline are relatively long-lasting and often include:

  • Synesthesia
  • Hallucinations
  • Nausea
  • Chills or fever
  • Extreme perspiration
  • Accelerated heart rate
  • Increased blood pressure
  • Dilated pupils
  • Mood swings
  • Extreme anxiety
  • Heightened sensory experiences
  • Alterations in the perception of the passing of time

Dissociative Hallucinogenic Drugs

Substances in the subcategory of dissociative hallucinogenic drugs are more likely to produce significant alterations of reality (dissociative experiences) in addition to the other hallucinogenic effects that occur with classic hallucinogens. Dissociative experiences can be classified as either being related to feelings of:

  • Derealization: the perception that the environment is not real or that an individual is somehow outside of the environment (or reality)
  • Depersonalization: the feeling that one is leaving one’s body or that one is not real

Several drugs are considered to be dissociative hallucinogenic drugs.


N, N-Dimethyltryptamine (DMT) is a dissociative hallucinogenic substance that is extracted from the leaves and shoots of the tropical vine ayahuasca that grows in Central America and South America. DMT can be used in a powder or pill form. It can also be used as a tea or chewed from the ground leaves of the plant. The effects of DMT include:

  • Improved attention at low doses but distractibility at higher doses
  • Enhance perceptual experiences
  • Hallucinations
  • Alterations of mood states
  • Alterations in the perception of the passage of time
  • Dissociative effects
  • Increases in body temperature, heart rate, blood pressure, and breathing
  • Nausea and vomiting


Phencyclidine (PCP) was originally developed to be used as an anesthetic drug, but its use was discontinued due to a number of potentially dangerous side effects. It is often more readily recognized as a dangerous substance by its street name, angel dust, and has justifiably received a reputation of being a very potentially dangerous substance. It has differential effects depending on the amount taken:

  • At lower doses, the effects often appear to be similar to alcohol intoxication, including:
    1. Issues with balance and motor coordination
    2. Slurred speech
    3. Bloodshot eyes
    4. Giddiness

    Individuals under the influence of low doses of PCP will experience hallucinations and dissociative effects. They may even become aggressive and believe they are invincible.

  • People using moderate doses of PCP will experience many of the above effects but will often appear to be more heavily sedated and may even become unconscious.
  • People taking high doses of PCP will initially experience the effects that occur at lower doses but in a more intensified state and also risk the development of seizures and coma.

Chronic use of PCP has been demonstrated to be associated with irreversible brain damage in a number of research studies that have investigated its effects in laboratory animals and in chronic users of the drug.


Ketamine is a dissociative hallucinogenic drug that was developed to be used as an analgesic drug (for the treatment of pain) and as an anesthetic. The use of the drug was associated with a number of serious side effects, and it is only used as an anesthetic in special cases currently.

In the 1990s and the early part of the 2000s, ketamine was popular with adolescents and young adults who attended parties or clubs, but its use has significantly decreased in recent times. Ketamine is also a drug that has received some attention as potentially being useful in the treatment of clinical depression.

Ketamine has an unusual mechanism of action compared to other hallucinogenic drugs as it exerts a significant antagonistic effect on the excitatory neurotransmitter NMDA (N-methyl-d-aspirate). Using ketamine results in:

  • Sedation and even confusion at lower to moderate doses (often referred to as a type of hypnotic state)
  • Hallucinations and a comatose state at high doses
  • Significant dissociative effects that can include both derealization and depersonalization
  • A reduction in the subjective experience of pain
  • Autonomic nervous system effects that include significant increases in body temperature, blood pressure, and heart rate
  • Cognitive impairments that can occur when one is under the influence of the drug, such as significant memory loss for things that happen while under the influence of the drug, as well as significant issues with attention and memory long after use has stopped


abuse of hallucinogens like ketamine and pcp

The majority of research regarding use of hallucinogenic drugs indicates that most of the drugs in this class have a relatively low potential for abuse and even for the development of physical dependence. Most of the drugs do result in the development of tolerance in individuals who chronically use them, but the withdrawal syndrome associated with discontinuation is not well documented for the majority of hallucinogenic drugs except for ketamine and PCP. In cases where withdrawal symptoms are reported, they are primarily issues with depression, anxiety, irritability, and other psychological symptoms. They are not considered to be potentially life-threatening in the same way that other withdrawal symptoms are (e.g., the withdrawal syndrome for benzodiazepines and alcohol), except in cases where individuals may become suicidal or be prone to accidents or poor judgment.

Any substance can be a substance of abuse when it is used in a manner that results in an individual experiencing significant distress or functional impairment in life. Hallucinogenic drugs do have specific diagnostic criteria to determine if individuals who use them have developed some form of substance use disorder. Separate criteria for a PCP use disorder and for other hallucinogenic substances are listed by the American Psychiatric Association (APA), indicating that there are specific issues related to PCP use that are not believed to relate to the use of other hallucinogenic drugs.

In terms of a clinical diagnosis, a substance use disorder may be present when a person:

  • Experiences significant problems with functioning due to substance use
  • Has frequent cravings to use the substance
  • Spends significant amounts of time using the drug or trying to get the drug
  • Gives up important activities or personal responsibilities as a result of using the drug
  • Frequently uses the drug in situations where it is dangerous to do so
  • Develops significant tolerance to the drug

Anyone who uses any hallucinogenic substance and experiences issues associated with use should suspect that they may have an abuse issue and should seek formal medical detox program for drug misuse and tailored treatments.

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