What are Hallucinogens (Psychedelic Drugs)?

Assortment of Hallucinogens | La Hacienda

Hallucinogens are a varied class of substances that change a person’s perception of their environment as well as their thoughts and sensations. They target specific brain centers to alter the brain’s interpretation of sensory input. 

The National Institute on Drug Abuse says there are two categories of hallucinogens: classic (such as LSD) and dissociative (such as PCP). Both types can produce hallucinations, or sensations and images that appear real but are not.

Dissociative drugs can also cause a sensation of being out of control or removed from body and environment.

The chemical structures of many hallucinogens are similar to those of natural neurotransmitters such as serotonin, which plays a role in the control of behavioral, perceptual and regulatory systems. 

Most hallucinogens have great potential for abuse, have no accepted medical use in treatment, and are not proven safe for use without medical supervision. As such. they are classified as Schedule I drugs under the Controlled Substances Act.

History of Hallucinogens

Many ancient cultures used naturally occurring hallucinogens as part of religious practices. The Olmec civilization in South America, dating back to 12,000 BCE, buried their priests with Bufo Toads which produce a number of psychoactive substances on their skin.

The first synthetic hallucinogen, LSD (d-lysergic acid diethylamide) was created in 1938 in a Swiss laboratory. Scientists were looking for substances that would be useful in the treatment of alcoholism and mental disorders but ended up with a drug hundreds of times more powerful than the existing natural psychedelic drugs.

Hallucinogens achieved their widest popularity during the 1960s and early ’70s, when the hallucinogenic drug LSD and hallucinogenic mushrooms were significant to the “hippie” subculture. They diminished in popularity thereafter, but hallucinogens still have a following in some parts of the world and achieved renewed popularity as a “club drug” during the 1990s when LSD and Ecstasy were popular with American and European youth.

Classic Hallucinogens

LSD and Mushrooms as Examples of Hallucinogenic Substances | La Hacienda

Common Classic Hallucinogens

LSD/Acid – A powerful mind-altering drug, LSD is clear or white and odorless . It is created from lysergic acid, which is found in a fungus that grows on rye and other grains. Its potency is so great that low doses produce psychedelic effects.

Psilocybin — Psilocybin originates from a type of mushroom found in tropical and subtropical regions. They are popularly called magic mushrooms.

Mescaline — Mescaline is the main active ingredient of the peyote cactus, a small, spineless cactus. It can also be produced synthetically. While some medical professionals believe that mescaline can be effective in treating depression and alcoholism, federal agencies say its negative effects outweigh its positives.

Short-Term Effects of Classic Hallucinogens

These drugs can cause users to see images, hear sounds, and feel sensations that do not exist. The effects generally begin within 20 to 90 minutes and can last as long as 12 hours in some cases (LSD) or as short as 15 minutes in others (synthetic DMT). Hallucinogen users refer to the experiences brought on by these substances as “trips.” If the experience is unpleasant, users sometimes call it a “bad trip.”

Usually there are no sedative effects with these substances and users remember what happened. 

Hallucinogens are a diverse group of drugs, but share some specific short-term effects, including:

  • Increased blood pressure
  • Faster breathing
  • Higher body temperature
  • Appetite loss
  • Dry mouth
  • Sleeping problems
  • Spiritual experiences
  • Relaxation
  • Uncoordinated movements
  • Excessive sweating
  • Panic
  • Paranoia
  • Detachment from reality
  • Bizarre actions

Long-Term Effects of Classic Hallucinogens

Two long-term effects have been associated with use of this class of drugs, although such outcomes don’t occur often.

Persistent Psychosis

This is a series of continuing mental problems including visual disturbances, disorganized thinking, paranoia, and unexpected mood changes.

Hallucinogen Persisting Perception Disorder (HPPD)

HPPD involves reoccurring specific drug-related experiences such as hallucinations or other optical issues. These “flashbacks” often happen suddenly and may occur from within a few days to more than a year after drug use. They are sometimes mistaken for other medical issues such as stroke.

A history of mental illness may promote HPPD, but anyone can have the disorder, even if they used hallucinogens just once.

Behavioral therapies can help people deal with fear or confusion associated with visual issues that come with HPPD.

Dissociative Hallucinogens

Assorted Dissociative Drugs or Other Hallucinogens | La Hacienda

Common Dissociative Drugs

PCP — PCP (Phencyclidine) was developed in the 1950s as a general anesthetic for surgery, but due to serious side effects, it is no longer used for this purpose. It can be found in a variety of forms, including tablets or capsules; however, liquid and white crystal powder are most common

Ketamine — Ketamine is used as a surgery anesthetic for humans and animals. Much of the ketamine sold illegally in this country comes from veterinary offices. It comes as a powder or pills but is also available as an injectable liquid. Added to drinks it is used as a date-rape drug. Ketamine is being explored as a treatment for depression and post-traumatic stress disorder (PTSD), but more research is needed.

Dextromethorphan — Dextromethorphan (DXM) is a cough suppressant and mucus-clearing ingredient in some over-the-counter cold and cough medicines (syrups, tablets, and gel capsules).

Salvia –A plant common to southern Mexico and Central and South America, Salvia divinorum is ingested by chewing fresh leaves or by drinking extracted juices. It causes intense, short-lived hallucinogenic effects

Short-Term Effects of Dissociative Drugs

Effects can happen within minutes and last several hours; some users experience effects lasting days. Consequences depend on how much is used. In low and moderate doses, dissociative drugs can cause:

  • Numbness
  • Disorientation and loss of coordination
  • Hallucinations
  • Increase in blood pressure, heart rate, and body temperature

In high doses, they can cause the following:

  • Loss of memory
  • Anxiety and panic
  • Seizures
  • Psychotic symptoms
  • Immobility
  • Mood swings
  • Trouble breathing

Long-Term Effects of Dissociative Drugs

While more research and clinical trials are needed, there is evidence that addiction can result from repeated use of PCP. Effects that may continue for a year or more after cessation of use include:

  • Difficulty speaking
  • Loss of memory
  • Weight loss
  • Anxiety
  • Depression and/or suicidal thoughts

How Do They Affect the Brain?

Research suggests that they temporarily disrupt communication between brain chemical systems throughout the brain and spinal cord. Some interfere with the neurotransmitter serotonin which regulates:

  • Mood
  • Sensory perception
  • Sleep
  • Hunger
  • Body temperature
  • Sexual behavior
  • Intestinal muscle control

Dissociative hallucinogenic drugs also interrupt the effect of the brain chemical glutamate, which regulates:

  • Pain perception
  • Responses to the environment
  • Emotion
  • Learning and memory

Psychoactive Drugs Include Hallucinogens

Hallucinogens are part of a grouping called psychoactive drugs. Substances in this category alter the central nervous system’s normal activity, causing changes in mood, awareness, and behavior. Because they disrupt communication between brain cells, abusing them can lead to serious short- and long-term effects on the brain.

Four groups of drugs fall into this category

  • Depressants like alcohol and sleeping pills
  • Stimulants like nicotine and ecstasy
  • Opioids like heroin and pain medications
  • Hallucinogens like LSD

Not all of these drugs are illegal. Caffeine is a stimulant found in coffee and energy drinks, and opioids like Vicodin, OxyContin, or morphine are often prescribed by doctors to relieve pain.

Misusing prescriptions of these drugs is illegal and can be as dangerous as using cocaine or heroin.

Hallucinogens and Drug Abuse

The National Survey on Drug Use and Health (NSDUH), conducted annually by the Substance Abuse and Mental Health Services Administration (SAMHSA), provides nationally representative data on use of tobacco, alcohol, and illicit drugs.

Recent NSDUH surveys have not found a dramatic increase in the use of hallucinogens, and they rank far down the list of most-abused substances.

The largest percent using hallucinogens—7.2 percent—was among young adults ages 18 to 25. For adults ages 26 and older, use increased from 0.8 percent to 1.5 percent in the same study.

Can a Person Overdose on Hallucinogens?

At high doses, most classic hallucinogens may cause exceptionally disagreeable experiences but usually the adverse effects are not life-threatening.

An overdose is more likely with some dissociative drugs. Seizures, coma, and death may occur after taking large doses of PCP. Also, PCP combined with depressants can lead to a coma.

That said, users of both types of hallucinogens risk serious harm due to the intense altered state of consciousness and mood caused by these drugs. Users might do abnormal things, like jump in front of a car. Or they may experience profound suicidal feelings.

As with other uncontrolled substances, accidental poisoning may be caused by impurities or use of chemicals in dangerous proportions. And psilocybin users also run the risk of mistakenly consuming poisonous mushrooms.

Are hallucinogens addictive?

There is evidence that certain hallucinogens can be addictive, and that hallucinogen use can develop into a drug dependence regardless of a substance’s legal status.

LSD is not considered to be addictive because it doesn’t cause uncontrollable drug-seeking behavior. But LSD can produce psychological dependence, so some repeat users end up taking higher doses to achieve the same effect.

People who stop repetitive PCP use suffer withdrawal symptoms including drug cravings, headaches, and sweating.

The National Institute on Drug Abuse provides a very informative fact sheet on hallucinogens at its website (drugabuse.gov).

Drug Abuse Treatment at La Hacienda

Dr James Boon | La HaciendaLa Hacienda Treatment Center cares for women and men with substance use disorders including patients who have abused or become addicted to hallucinogens or other substances. Our board-certified addiction treatment physicians provide medical advice and address the reasons behind the addiction.

From the moment a patient or family member calls our Admission team, we start gathering personal data and medical history so that our medical and clinical teams can formulate an individualized treatment plan.

For more information about our treatment program, including recovery from use of hallucinogens or other drugs, please contact our on-site Admission team at (800) 749-6160.


LSD, a clear or white odorless material found in a fungus that grows on rye and other grains, is one of the most powerful mind-altering chemicals.

Peyote Cactus | La Hacienda


Mescaline is the main active ingredient of the peyote cactus , a small, spineless succulent. It can also be produced synthetically.

Psilocybin or Magic Mushrooms | La Hacienda


Psilocybin comes from certain types of mushrooms (popularly called magic mushrooms) found in tropical and subtropical regions.

Person Drinking Ayahuasca | La Hacienda


Ayahuasca, a drink brewed from the leaves of the Psychotria viridis shrub, contains DMT, a powerful hallucinogenic chemical. Ayahuasca has been used for centuries in spiritual ceremonies.