Hallucinogens make up a large and diverse group of drugs that change a person’s thoughts, feelings, and awareness of their surroundings. The effects of hallucinogen use vary greatly from substance to substance, although they all typically cause hallucinations, or seeing, hearing, feeling, smelling, or tasting something that is not real.1

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Types of Hallucinogens

Some hallucinogens are extracted from plants or mushrooms and some are synthetic or manufactured. Hallucinogens are divided into two main groups, including:1

  • Classic hallucinogens: Examples include LSD, peyote, psilocybin (“magic mushrooms”), and DMT.
  • Dissociative drugs: Examples include ketamine, PCP, and dextromethorphan (marketed under the brand name Robitussin).

Both classic hallucinogens and dissociative drugs can cause hallucinations, but dissociative drugs, in addition to causing hallucinations, can lead you to feel disconnected from your body or surroundings.1

Short-term Effects of Classic Hallucinogens

In general, the effects of the classic hallucinogens begin within 20 to 90 minutes of taking them, and the duration of the effects depends on the drug. With LSD, the effects can last as long as 12 hours, and with synthetic DMT, as short as 15 minutes.1 Every classic hallucinogen elicits different effects, but potential short-term effects of classic hallucinogen use may include:1,2

  • Hallucinations—seeing, hearing, and feeling things that seem real but are not
  • Anxiety
  • Digestive problems
  • Loss of appetite
  • Rapid heart rate
  • Increased body temperature, blood pressure, and breathing rate
  • Dilation of pupils
  • Muscle weakness
  • Exaggeration of normal reflexes
  • Dizziness
  • Muscle tremor
  • Sleep disturbances
  • Bizarre, erratic behavior
  • Panic
  • Paranoia
  • Psychosis

While many people who use hallucinogens report enlightening experiences, such as enhanced insight, a feeling of contentment, and heighted awareness, during a “trip,” using hallucinogens can also have dangerous consequences. Some people may believe they are invincible or have magical powers, and this could lead to life-threatening behaviors such as jumping out of a window. It is important to note that these reactions can happen for novice as well as experienced users.2

Although overdose on classic hallucinogens is fairly rare, there have been reports on overdoses on these substances, with life-threatening symptoms including convulsions and hyperthermia, a condition in which the body overheats. In the case of hyperthermia, seek immediate medical attention immediately to reduce the risk of death.2

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Long-term Effects of Classic Hallucinogens

The two main long-term effects of classic hallucinogens are persistent psychosis and hallucinogen persisting perception disorder (HPDD). Though these hallucinogen effects are rare, they can be of significant consequence.1 Moreover, because they are rare, they are also poorly understood from a scientific perspective and thus can be unpredictable.

Persistent psychosis is a series of mental and emotional problems that can include visual disturbances, disorganized thinking, paranoia, and mood changes.1

HPDD is what used to be called experiencing “flashbacks.” With this disorder, the perceptual changes that you experienced during a past hallucinogenic “trip” re-emerge without recent use of the drug.3

One study found that a majority of the HPDD cases had been induced by LSD.3 HPDD can occur more than a year after using LSD and can occur without warning.1

Are Classic Hallucinogens Addictive?

The addiction potential of classic hallucinogens, such as LSD, psilocybin, and DMT, is generally considered to be very low. That said, chronic LSD use can lead to tolerance, which means you need more of the hallucinogen to experience the same desired effect. Taking higher doses of LSD can have dangerous results, such as overdose and death.1

Short-term Effects of Dissociative Drugs

The effects of dissociative drugs, such as PCP and ketamine, can begin within a few minutes of taking them and can last several hours. Some people may even experience the effects for a few days following the initial dose.1

The effects of dissociative drugs depend on the dose. In low and moderate doses, they can cause:1

  • Increased heart rate
  • Increased body temperature
  • Increased blood pressure
  • Disorientation
  • Numbness
  • Loss of coordination
  • Hallucinations

In high doses, dissociative drugs can cause:1

  • Trouble breathing
  • Mood swings
  • Memory loss
  • Seizures
  • Psychotic symptoms (losing touch with reality)
  • Amnesia
  • Inability to move
  • Panic and anxiety

PCP Effects

With PCP specifically, you can feel the effects within 20 to 30 minutes after taking the dose orally and two to three minutes after smoking it. The effects can last from three to eight hours.2 The effects of PCP use depending on the strength of the dose may include:2

  • Mild (5 mg): Staggering gait, slurred speech, numbness of extremities, agitation, skin flushing, depression
  • Moderate (5-10 mg): Involuntary rapid eye movement, dizziness, rapid heart rate, impaired coordination, paranoia, severe anxiety
  • Severe (10-25 mg): High risk of death, vomiting, seizures, coma, extremely slow reaction time if conscious

If you or someone you know is experiencing severe side effects, call 911 immediately.

Long-term Effects of Dissociative Drugs

Repeated use of PCP can lead to:2

  • Addiction
  • Psychosis (loss of sense of reality) that can last for months after use

Other effects of PCP use may continue for up to a year or more after stopping use. These effects can include:1,2

  • Depression
  • Anxiety
  • Suicidal thoughts
  • Speech problems
  • Memory loss
  • Weight loss

More research is needed to determine if you can develop a tolerance to PCP. However, it is addictive and you can develop a physiological dependence on this dissociative drug. If you are dependent on PCP and abruptly stop using it, withdrawal symptoms may emerge. PCP withdrawal symptoms may include:1

  • Cravings
  • Headaches
  • Excessive sweating

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Dangers of Hallucinogens

With hallucinogens, the possibility of overdose depends on the drug and is more likely with some dissociative drugs.2

Using PCP in high doses can cause seizures, coma, and death. Further, taking PCP with alcohol, benzodiazepines, or other such central nervous system depressants can cause a coma.1,2

Both types of hallucinogens—classic hallucinogens and dissociative drugs—have a very high risk of serious harm related to the significant changes in perception and moods that they cause. That is, while under the influence of hallucinations, users might:1

  • Experience suicidal feelings and act on them
  • Take risks they wouldn’t otherwise take, such as jumping off a roof or driving a car
  • Become accidentally poisoned due to contaminants in the drug

Treatment for Hallucinogen Addiction

There currently is no FDA-approved medication used to treat addiction to hallucinogens.1 With regard to the treatment of HPDD, medications such as antidepressants and anti-anxiety medications are a possibility.4

Various behavioral therapies are used to treat a hallucinogen addiction, although more research is needed in order to determine which behavioral therapies are most effective.1,5 There are many types of behavioral therapies, but most work to change unhealthy or maladaptive behaviors, such as substance use, and replace them with healthier behaviors. Many of these therapies equip patients with coping skills and relapse-prevention strategies they can use when they are experiencing cravings or drug-using triggers.

Treatment for hallucinogen addiction can occur on an inpatient or outpatient basis. Inpatient treatment requires that you live at the facility for the duration of the program, while receiving several treatment interventions, such as:

  • Individual therapy
  • Group counseling
  • Family therapy
  • Support groups
  • Alternative approaches, such as yoga and meditation

Conversely, outpatient treatment gives you the freedom to continue going to work or attending school while receiving addiction treatment. You attend scheduled treatment sessions at a facility or center. Outpatient recovery programs vary considerably in intensity, ranging from a couple of hours of therapy per week to several hours per day.

If you are concerned about your use of hallucinogens or that of a loved one, call 800-934-1582(Who Answers?) for 24/7 help.


  1. National Institute on Drug Abuse. (2019). Hallucinogens DrugFacts.
  2. Doweiko, H.E. (2006). Hallucinogen abuse and addiction. Concepts of Chemical Dependency. (pp 197-212). Cengage.
  3. Giovanni Martinotti, G., Santacroce, R., Pettorruso, M., Montemitro, C., Spano, M.C., Lorusso, M., di Giannantonio, M., & Lerner, A.G. (2018). Hallucinogen persisting perception disorder: Etiology, clinical features, and therapeutic perspectives. Brain Sciences, 8(3), 47.
  4. Orsolini1, L., Papanti1, G.D., De Berardis, D., Guirguis, A., Corkery, J.M., & Schifano, F. (2017). The “endless trip” among the NPS users: Psychopathology and psychopharmacology in the hallucinogen-persisting perception disorder. A systematic review. Frontiers in Psychiatry, 8, 240.
  5. Hardaway, R., Schweitzer, J. & Suzuki, J. (2016). Hallucinogen use disorders. Child & Adolescent Psychiatric Clinics, 25, 489-496.

the Take-Away

Hallucinogens are a group of drugs that produce hallucinations in users. All forms of hallucinogens are illegal in the United States and have potentially dangerous qualities.