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Hallucinogens Effects: Long- And Short-Term Brain & Body Harm

Last Updated: March 20, 2024

Reviewed by Dr. Ash Bhatt

Despite the side effects of hallucinogens are often chased by those who abuse drugs, these side effects are far from pleasant. The side effects of hallucinogens not only harm one’s health; they are also life-threatening. That’s why it is important for users to know about the side effects of hallucinogens.

Short-Term Effects Of Hallucinogens

Given that there are multiple types of these drugs, drugs that are hallucinogens can have a wide variety of side effects. The short-term effects of hallucinogens are those that are first observed, occurring within minutes of the drug being taken in some cases. While these may not be long-lasting, they are still highly dangerous.

Hallucinogens’ short-term effects include: 

  • Agitation
  • Dizziness and sleeplessness
  • Feelings of relaxation
  • Flushing
  • Hallucinations
  • Impulsiveness and rapid emotional shifts
  • Increased blood pressure
  • Increased blood heart rate
  • Increased body temperature
  • Introspective/spiritual experiences
  • Loss of appetite
  • Dry mouth
  • Nervousness
  • Paranoia
  • Panic reactions
  • Numbness
  • Weakness
  • Tremors
  • Profound sweating
  • Severe vomiting
  • Uncoordinated movements
  • Profoundly altered state of awareness and perceptions of otherworldly imagery

Long-Term Effects Of Hallucinogens

Hallucinogens also have long-term effects. While these are less likely to result in sudden death, they can create conditions that make life difficult, unenjoyable, and may even contribute to medical problems that prove deadly.

Some long-term effects of hallucinogens include:

  • Weight loss
  • Violent behavior
  • Increased panic
  • Impaired concentration
  • Substance use disorder or addiction

Hallucinogen Persisting Perception Disorder

Hallucinogen Persisting Perception Disorder (HPPD) is defined by visual phenomena that users experience long-term after the use of hallucinogenic drugs. The individual experiencing HPPD does not need to have any pre-existing psychological issues. This condition is not the same as psychosis, which can also result from the use of psychedelics. Patients with this condition know that the things they are seeing are not part of reality.

Hallucinogens And Schizophrenia

Hallucinogenic drugs can induce psychosis, which in some ways can look similar to schizophrenia. Additionally, the side effects of using hallucinogens can themselves be very similar to the disease. They are so similar, in fact, that their effects on schizophrenia have been investigated. However, no conclusive evidence has demonstrated that psychedelics can induce schizophrenia. On the contrary, doctors are currently considering how they might be able to treat the condition.

effects of hallucinogens on the brain

How Do Hallucinogens Affect The Brain?

The side effects of hallucinogens on the brain are perhaps the most important to understand, as these tend to be the most profound symptoms of use and the longest lasting. Additionally, the psychological effects of hallucinogens can be the most debilitating. These include ongoing psychosis, depression, mood disturbances, and paranoia. Users suffering from these conditions can find themselves unable to function in their day-to-day lives. However, hallucinogens effects on the brain are not limited to the psychological.

Other symptoms of use include:

  • Memory loss
  • Disorganized thinking
  • Persistent Flashbacks
  • Hallucinations
  • Difficulty with speech and thought
  • Other visual disturbances such as seeing halos or trails attached to moving objects

How Do Hallucinogens Affect The Body?

The exact effects of hallucinogens on the body will depend on the drug taken. Additionally, the physiological effects of hallucinogens are somewhat unpredictable.

Some potential symptoms that could be experienced include: 

  • Increased blood pressure
  • Increased heart rate
  • Increased body temperature
  • Dizziness
  • Loss of appetite
  • Dry mouth
  • Sweating
  • Numbness
  • Nausea
  • Weakness
  • Uncoordinated movements (ataxia)
  • Tremors
  • The potential for poisoning and the after-effects of this
  • Seizures
  • Coma

Additionally, if someone has been taking hallucinogens for a long time, they may experience withdrawal symptoms of hallucinogens when they go too long between doses.

Bad Trips On Hallucinogenic Drugs

While the goal of taking these drugs is to get some sort of high or a “trip” (what is illegal), this experience is not necessarily pleasant. In fact, bad trips are quite common. Given that these drugs are so unpredictable, every use risks a nightmarish experience.

This is highly problematic given how long trips can last—as much as 12 hours. On a bad trip, this can be absolutely agonizing. Perhaps the worst part is that once the bad trip starts, the user cannot do anything to stop it—they simply have to wait it out.

bad trip on hallucinogens

Some potential side effects of hallucinogens and bad trips are:

  • Extreme fear
  • Panic
  • Anxiety
  • A sense that they have gone insane
  • Terrifying visions, sounds, and sensations
  • A desire to harm others, either as perceived self-defense or simply to hurt
  • A desire to harm themselves to escape the bad trip
  • A sense that they are dying
  • A distortion of the perception of time and space in a manner that is disturbing
  • A failure to recognize external stimuli, leading to significant harm

Social Effects Of Hallucinogens

As with any drug, there are potential social effects of the use of hallucinogenic drugs. These include:

  • The emotional burden placed on others
  • An inability to perform at work or school
  • Being unable to participate in critical family tasks
  • Changing social groups
  • Struggling to converse about topics unrelated to drug use
  • Economic struggles
  • Difficulty leaving the house
  • A lack of understanding of social situations due to changes in the brain

death on hallucinogens

Can Hallucinogens Kill Someone?

Quite simply, the answer is yes—people can die from psychedelic drugs, either by overdosing on them alone or by mixing them with other substances, resulting in extreme toxicity. However, overdose as a side effect of hallucinogens is rare.

Perhaps the greater risk comes from what occurs during a bad trip. Given that one of the dangers of hallucinogens is that they can make people act in ways they otherwise would not, including being unaware that certain actions can harm them and engaging in risk-taking behaviors, there is the possibility of a person dying as a direct result of taking them. While it might not be an overdose, the end result is still a life lost.

Getting Help With Hallucinogen Abuse

If someone is taking hallucinogenic drugs, they need help safely ending use before negative consequences occur. Drug rehab centers know how to treat psychedelics dependence and help people get clean. With the right treatment, patients can expect long-lasting results.

Page Sources

  1. Daley DC. Family and social aspects of substance use disorders and treatment. Journal of Food and Drug Analysis. 2013; 21(4): S73–S76. doi:10.1016/j.jfda.2013.09.038. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4158844/.
  2. Hallucinogens. National Institute on Drug Abuse. 2019. https://www.drugabuse.gov/publications/drugfacts/hallucinogens.
  3. Hermle L, Simon M, Ruchsow M, Geppert M. Hallucinogen-persisting perception disorder. Therapeutic Advances in Psychopharmacology. 2012; 2(5): 199–205. doi:10.1177/2045125312451270. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3736944/.

Published on: March 16th, 2024

Updated on: March 20th, 2024

About Author

Peter J. Grinspoon, MD

Dr. Peter Grinspoon is an experienced physician with long-term clinical practice experience. As a former analgesic addict, Dr. Grinspoon knows precisely how important it is to provide patients with effective treatment and support. Medical writing for him is the way to communicate with people and inform them about their health.

Medically Reviewed by

Dr. Ash Bhatt

Throughout his professional life, Dr. Bhatt has been conferred with diplomate status by the American Board of Psychiatry and Neurology, certifying him in both adult and child/adolescent psychiatry. His experiences in emergency rooms, frequently encountering patients with simultaneous health and addiction issues, directed his attention to these specific fields.


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