The hallucinogen drug category is made up of a diverse group of substances that have a primary psychoactive effect. Hallucinogens can cause altered perceptions, dreamlike experiences and subjective changes to one’s consciousness. There are many kinds of hallucinogenic drugs, and they may be naturally occurring (mescaline, for example) or synthetic (LSD, for example).

Importantly, hallucinogens are defined as having a primary psychoactive effect. This means the intended effect is to alter perceptions and cause hallucinations. Drugs like amphetamines and ecstasy may cause hallucinations as a secondary effect, but they are not used with the intent to cause hallucinations.

Are Hallucinogens Addictive?

Some hallucinogenic drugs are more addictive than others. Hallucinogens can be broadly grouped into two categories:

  • Classical hallucinogens, often known as “psychedelics,” include LSD, mescaline, ayahuasca, and psilocybin. These drugs are generally not considered to be addictive. A review evaluating the abuse potential of medically administered psilocybin determined that it should be classified as a Schedule IV drug if it is made legal for medicinal use. Schedule IV drugs have a low potential for misuse. However, regular use of any of these drugs can lead to the development of tolerance, meaning that ever-increasing doses of the drug must be taken in order to achieve the desired effect. Research has found that the use of classical hallucinogens is not an independent risk factor for mental health problems.
  • Dissociative hallucinogens include ketamine, nitrous oxide (laughing gas), dextromethorphan (the active ingredient in over-the-counter cough syrup) and PCP. Interestingly, the Drug Enforcement Agency and the Food and Drug Administration consider dissociative hallucinogens to be safer than classical hallucinogens. This is despite the fact that there is a very real risk for addiction when dissociative hallucinogens are used regularly. Additionally, dissociative hallucinogens have been linked to negative physical and psychological consequences.

Signs of Hallucinogen Abuse

Drug abuse is typically characterized by a number of warning signs and symptoms, including:

  • Symptoms of Hallucinogen Abuse

    Loss of interest in normal hobbies or activities

    Behavioral changes (evasiveness, rapid mood swings)

    Missing school or work

    Worsening performance at school or work

    Changes in personal hygiene

Side Effects of Hallucinogens

Recent studies have shed light on the physical and psychological consequences of hallucinogen use. It is important to differentiate between classical and dissociative hallucinogens, as they are associated with different side effect profiles.

Side Effects of Classical Hallucinogens

All classical hallucinogens are listed as Schedule I drugs by the DEA. This means the federal government does not recognize these drugs as having any medicinal value and considers them to have a high risk of abuse. However, mounting evidence suggests that classical hallucinogens may be beneficial in the treatment of several mental health disorders.

Short-term effects of classical hallucinogens generally set in within 20 to 90 minutes after taking the drug. These effects may last anywhere from 15 minutes to 12 hours, depending on the type of drug. Hallucinogenic drugs are associated with both positive and negative short-term side effects.

Positive short-term effects include:

  • Positive Short-Term Effects of Hallucinogens

    Intensified sensory perception (colors appear brighter)

    Altered sense of time and space

    Hallucinations (which may also be negative)



    Reduced sensitivity to perceived social rejection

    Increased emotional empathy

Negative short-term effects include:

  • Negative Short-Term Effects of Hallucinogens

    Hallucinations (which may also be positive)



    Elevated heart rate


Long-term effects of classical hallucinogens remain relatively unknown due to federal restrictions on research. However, in light of promising findings that suggest that classical hallucinogens may have significant therapeutic benefits, more research is being permitted.

Research that found positive long-term side effects is as follows:

  • A recent study of 16 adults evaluated the long-term effects of a single dose of LSD. One year after LSD administration, those who took LSD considered the experience to be “personally meaningful” with “long-lasting subjective positive effects.” Of the participants, 10 rated the experience as “among the top 10 most meaningful experiences in their lives.” However, this study does not address the long-term effects of recreational hallucinogen use.
  • A study on the long-term effects of psilocybin found that participants had increased and enduring positive changes six months after taking the drug. Larger doses of psilocybin were linked to a greater increase in positive changes, and 72% of people who took a high dose reported a significantly increased sense of well-being or life satisfaction. The same was true for 92% of people who took a high dose and also participated in regular support groups. Only 20% of the low-dose group reported a sustained increase in well-being.
  • A study evaluating the effects of a single dose of psilocybin administered to cancer patients found immediate, substantial improvements in anxiety and depression. These improvements persisted for 6.5 months after administration. In addition, patients reported increased quality of life, improved attitudes toward death and reduced existential distress.
  • Psilocybin-induced activation of specific serotonin receptors in the brain was shown to reduce emotional pain. In addition, it reduced self-confidence problems that are associated with social rejection and negative social interactions.

Research that found negative long-term side effects is as follows:

  • A recent study evaluated the effects of hallucinogens on college students. It found that students who had used hallucinogens were more likely to have substance use disorders, mental health problems and impulsivity traits. However, this study was unable to directly attribute these outcomes to hallucinogen use. The students who reported using hallucinogens were also likely to misuse alcohol and other drugs.
  • There is a potential for the development of hallucinogen persisting perception disorder (HPPD). Although it is poorly understood, HPPD is characterized by “flashbacks” that include perceptual disturbances and hallucinations. While some people report that they are not bothered by these flashback experiences, others may experience emotional distress and impairment. Evidence suggests that HPPD may be linked to pre-existing psychiatric conditions. HPPD is believed to occur in 4.2% of people who use hallucinogens.

Currently, classical hallucinogens are generally not associated with significant negative side effects when they are administered in a clinical setting. However, there is some evidence that using hallucinogens recreationally or with other drugs may increase the risk of negative long-term side effects.

Side Effects of Dissociative Hallucinogens

Dissociative hallucinogens can cause dissociation, or detachment from reality. Unlike classical hallucinogens, many dissociative hallucinogens can be prescribed or even purchased over the counter.

Dissociative hallucinogens have a wider spectrum of short- and long-term effects than classical hallucinogens. Because of this, it is difficult to describe a side effect profile that applies to all dissociative hallucinogens.

Short-term effects commonly include:

  • Dissociative Hallucinogens Short-Term Effects




    Detachment from life stressors and mental distress


    Increased blood pressure

    Memory loss


    Inability to move

    Respiratory depression

Long-term effects are quite diverse and depend on the drug that is used. Common drugs and their side effects include:

Dissociative Hallucinogens Long-Term Effects

  • Ketamine

    When provided by medical professionals and taken as prescribed, ketamine can be an effective antidepressant drug for people with treatment-resistant depression. However, chronic ketamine misuse can lead to dependence and addiction. It can also impair learning and memory, cause severe and widespread brain damage and cause liver, kidney and bladder injury.

  • Dextromethorphan (DXM)

    DXM is the active ingredient in many over-the-counter cough syrup formulations. Some data suggests that DXM can have positive effects on depression, pain, Parkinson’s disease, and other conditions. Unfortunately, some teens will consume an entire bottle of cough syrup in one sitting to experience the hallucinogenic effects of DXM. This puts them at risk for DXM toxicity and can lead to psychosis, respiratory depression, seizures, coma, and even death. In addition, DXM is often consumed with alcohol, which significantly increases the risks of overdose.

  • Phencyclidine (PCP)

    PCP was used as a general anesthetic in the 1950s, but its use was discontinued due to the hallucinogenic effects that followed. PCP has become a popular recreational drug, but it is associated with very serious negative consequences. These side effects include mild to severe agitation, delusions, violent behavior, seizures, coma, and death. In addition, some evidence suggests that PCP can induce the onset of schizophrenia.

Side Effects of Polysubstance Abuse

Polysubstance abuse is defined as the simultaneous misuse of more than one drug. Common drugs that are misused with hallucinogens include alcohol, cocaine, marijuana, opioids, and amphetamines.

Polydrug abuse may significantly increase the likelihood of negative outcomes. It can lead to someone experiencing a “bad trip” (scary hallucinations, paranoia, the feeling that the trip will never end) and can encourage erratic and dangerous behavior. Polysubstance abuse with dissociative hallucinogens increases the risk of an overdose.

Can You Overdose on Hallucinogens?

While classical hallucinogens are not typically associated with overdose, some dissociative hallucinogens are. PCP is associated with potentially lethal overdoses, especially when it is combined with other drugs. DXM overdose can also be lethal, especially when it is used with alcohol. Ketamine is not associated with serious overdose consequences when it is taken alone, but it can cause respiratory depression when it is combined with other drugs that slow brain activity (alcohol, opioids).

Hallucinogen Withdrawal and Addiction Treatment

Classical hallucinogens are not associated with withdrawal or addiction, but some dissociative hallucinogens are. There are no FDA-approved medications for hallucinogen treatment, but quality rehab facilities can provide cognitive behavioral therapy and other evidence-based therapies during the recovery process. These approaches can be incredibly helpful for people who are struggling to overcome dependence or addiction related to dissociative hallucinogens.

Our Drug Detox and Inpatient Rehab Center

The Recovery Village Palm Beach at Baptist Health

4905 Lantana Rd
Lake Worth, FL 33463


Key Points: Hallucinogens Addiction

Some key points to remember about hallucinogens include:

  • There are two main groups of hallucinogenic drugs: classical (LSD, mescaline) and dissociative (ketamine, PCP).
  • Classical hallucinogens are generally not believed to cause addiction, while dissociative hallucinogens are more likely to cause addiction.
  • Hallucinogens are associated with positive and negative side effects.
  • In a clinical setting, many classical and dissociative hallucinogens are proving to be valuable therapies for mental health disorders.
  • Recreational use of hallucinogens may lead to negative outcomes, including erratic behavior, panic or anxiety.
  • Some dissociative hallucinogens can cause life-threatening overdoses.

If you or someone you know is struggling with hallucinogen misuse or addiction, The Recovery Village Palm Beach can help. Contact us today to learn about evidence-based drug addiction treatment programs that can work well for your situation.