How Hallucinogens Affect the Body

The category of drugs known as hallucinogens covers a wide range of s­­­ubstances.1 The effects of hallucinogens on the body affect the way a person’s mind and nervous system take in stimulation from the environment. Hallucinogens also reportedly change the way people process “their own thoughts and feelings.”1

In this Article:

What Are Hallucinogens?

The U.S. National Institute on Drug Abuse (NIDA) separates hallucinogens into two categories based on their effects: classic hallucinogens and dissociative drugs. NIDA describes hallucinations as an experience that leads people to sense or perceive things that do not exist in reality. Dissociation describes a set of experiences where people feel detached or separate from themselves or their environment.1

Hallucinogens can come from natural sources, including some plants and fungus (e.g., mushrooms). Other hallucinogens can come from manmade or synthetic formulas.1

Some common hallucinogens include:1, 2, 3


Mixed senses and an altered perception of time are common hallucinogen side effects.

The risks associated with these substances differ depending on the type of hallucinogen used.3 Using some of these substances can lead to addiction, tolerance, withdrawal, or a combination of these symptoms.1,2

What Are the Physical Effects of Hallucinogen Use?

Some of the most prevalent physical effects of hallucinogens relate to the functioning of the brain and central nervous system.1 Hallucinogens can alter chemicals in your brain and influence your perception and other systems in your body. These effects can include:1

  • Mood changes
  • Sleep disturbance
  • Changes in appetite
  • Changes in body temperature
  • Changes in sexual functioning
  • Changes to muscle control in the intestines
  • Changes in learning ability
  • Changes in memory

Although the short- and long-term effects of hallucinogens on the body vary depending on the type of hallucinogen used, there are some general effects caused by this class of drugs.

General short-term effects of all hallucinogens include:1

  • Higher heart rate
  • Nausea
  • Changes to the perception of the passage of time
  • Changes to the perception of senses and physical sensations

Short-Term Effects of Classic Hallucinogens

LSD, psilocybin, peyote, DMT, and ayahuasca are categorized as “classic hallucinogens.”1 The short-term effects of these hallucinogens include:1, 2

  • Dry mouth
  • Tremors
  • Agitation
  • Increased rate of breathing
  • Loss of appetite
  • Raised body temperature
  • Raised blood pressure
  • Increased sweating
  • Flush skin
  • Feelings of panic
  • Loss of physical coordination
  • Feeling relaxed

If you use “classic hallucinogens,” you may experience changes in your brain functioning that can potentially lead to the development of psychosis.1 While NIDA summarizes the effects of psychosis as “disordered thinking detached from reality,” the experience of psychosis can involve two different experiences known as hallucinations and delusions.1, 3

Hallucinations can include seeing, hearing, smelling, feeling, and tasting things that do not exist in reality.3 Delusions describe changes to thoughts and beliefs that also do not reflect reality. One type of delusional experience associated with “classic hallucinogens” is paranoia or an “extreme and unreasonable distrust of others.”1, 3

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Short-Term Effects of Dissociative Hallucinogens

PCP, ketamine, DXM, and salvia are all examples of dissociative substances.1 The short-term effects associated with dissociative hallucinogens depend on the amount of the substance taken and may include:1

  • Loss of coordination
  • Disorientation
  • Raised blood pressure
  • Increased heart rate
  • Higher body temperature
  • Feeling numb
  • Difficulty breathing
  • Difficulty moving
  • Changes in mood
  • Anxiety
  • Symptoms of panic
  • Memory problems
  • Seizures
  • Symptoms of psychosis

Long-Term Effects of Hallucinogens

NIDA divides the long-term effects of “classic hallucinogens” into two categories. The first category of long-term effects is persistent psychosis—a set of psychotic symptoms that continue for an extended period of time following hallucinogen use.1

The second category is hallucinogen persisting perception disorder.1 Sometimes referred to as “flashbacks,” this disorder can occur even after you have stopped using hallucinogens, sometimes years following the last use.1, 3 This disorder refers to the return of perceptual disturbances, like hallucinations, that occur after you stop using hallucinogens.1, 3

The use of dissociative hallucinogens, such as PCP, can cause several long-term physiological effects, including addiction.1 Other long-term effects from this type of hallucinogen include:1

  • Anxiety
  • Depression
  • Weight loss
  • Problems with speech
  • Suicidal ideation

What Are Other Risks Associated with Hallucinogen Use?

Because hallucinogens distort a person’s perception of reality, the use of this type of drug can lead to bizarre or dangerous behavior.2 Due to changes in perception and sensations, you may take more risks than normal while using hallucinogens.1

Beyond the behavioral risks associated with using these substances, there’s also the risk of consuming contaminated hallucinogens.1 When consuming drugs purchased from illicit sources, you may ingest other chemicals or substances you did not expect. Hallucinogens may come mixed or “cut” with other substances, resulting in accidental poisoning.1

Hallucinogen Tolerance, Dependence, Addiction, and Withdrawal

Using some types of hallucinogens, such as LSD, over time can result in your body developing tolerance, where you need a larger amount of a substance to get a desired outcome.3, 4

Misusing some hallucinogens can cause you to develop dependence or an addiction.3, 5 People who become addicted to PCP may need to continue using it to function normally.5 This dependence can cause withdrawal symptoms when you attempt to stop using PCP.

Withdrawal effects of PCP include:5

  • Feelings of anxiety
  • Tension
  • Confusion
  • Irritable mood
  • Hallucinations
  • Seizures
  • Reduced body weight
  • Higher body temperature

Misuse of MDMA can also potentially develop into.6 The effects of MDMA resemble those of both hallucinogens and stimulants. Potential withdrawal symptoms that can occur when detoxing from MDMA include:6

  • Depressed mood
  • Difficulty concentrating
  • Changes in appetite
  • Loss of energy

The use of certain hallucinogens can be dangerous and even life-threatening.1, 2 When taken in large doses, PCP can cause organ failure, heart problems, muscle problems, and death.5 The raised body temperature associated with MDMA use can also lead to organ or heart failure and increase your risk of developing life-threatening physical health problems.6

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What Are Treatments for Hallucinogen Use?

If you are affected by hallucinogen use, misuse, or addiction, substance use treatment can offer a path to recovery.4, 5

Starting with withdrawal management, substance use treatment professionals can help you safely remove addictive hallucinogens from your system.7 Detox services can take place in hospitals, residential treatment centers, and outpatient programs that are appropriate for the severity of your symptoms and need.

Certain hallucinogen intoxication and withdrawal symptoms can complicate the detoxification process.1, 3, 7 Suicidal ideation, aggressive behavior, and symptoms of psychosis can make inpatient hospitalization a safer alternative to residential or outpatient withdrawal management services.7

An assessment from a qualified treatment professional can offer an accurate diagnosis and assessment of your needs in treatment.7 Following detox, you can begin the level of care that makes you feel empowered and motivated in your recovery, as well as offers the services proven to provide more positive recovery outcomes for individuals with your diagnosis, background, and other needs.

Services offered by treatment programs vary depending on their approach to recovery and available resources.7 Services available in substance use treatment programs include:7

  • Individual counseling
  • Family therapy
  • Medication management
  • Physical healthcare for medical conditions
  • Holistic interventions
  • Skills training
  • Stress management
  • Group therapy
  • Peer-led and mutual support groups

Case management services at any level of care can help you navigate any logistics, personal challenges, or barriers to help you fully engage in the treatment process.7

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  1. National Institute on Drug Abuse. (2019). Hallucinogens DrugFacts.
  2. National Institute on Drug Abuse. (2015). Hallucinogens and dissociative drugs: Research report.
  3. American Psychiatric Association (2013). Diagnostic and statistical manual of mental disorders (5th ed.).
  4. U.S. National Library of Medicine. (2021, June 10). Substance use – LSD.
  5. U.S. National Library of Medicine. (2021, June 10). Substance use – phencyclidine (PCP).
  6. National Institute on Drug Abuse. (2020). MDMA (Ecstasy/Molly) DrugFacts
  7. Miller, W. R., Forcehimes, A. A., & Zweben, A. (2019). Treating addiction: A guide for professionals. The Guilford Press.

the Take-Away

Hallucinogens have strong effects on the body and mind, causing delusions and even psychosis. Long-term use of hallucinogens can lead to addiction and serious mental health issues.