What Is Hallucinogen Persisting Perception Disorder (Flashbacks)?

Distorted reality
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What Is Hallucinogen Persisting Perception Disorder (Flashbacks)?

Flashbacks are common among people who use hallucinogenic drugs, and while drug-related flashbacks have a reputation for being disturbing or just the result of a "bad trip," not everyone who experiences flashbacks finds them troubling.

But sometimes, these flashbacks can be intense, unpleasant, and frequent, even if the person experiencing them is currently abstaining from drug use.

Flashbacks that continue to occur after the original drug effects have worn off are a medically recognized phenomenon, which is documented in the Diagnostic and Statistical Manual of Mental Disorders (DSM-5) as hallucinogen persisting perception disorder (flashbacks).


A drug-related flashback is the sensation of re-experiencing the effects of a drug after the true effects of the drug have worn off. Most often, this type of flashback is associated with the re-experiencing of the effects of a hallucinogenic drug such as LSD ("acid") or magic mushrooms.

Flashbacks typically happen in the days or weeks following ingestion of the drug but can happen months or even years after the drug use has been discontinued.

Flashbacks are not usually as intense or long-lasting as an actual drug experience, usually lasting just seconds or minutes, and are easier to control mentally than intoxication or a bad trip.

Symptoms of hallucinogen persisting perception disorder (HPPD) include:

  • An image of an object despite it not being there anymore (palinopsia)
  • False perceptions of movement out of the corner of the eye (peripheral vision)
  • Flashes of color
  • Hallucinations (especially of geometric forms)
  • Halos or trailing after-effects of images
  • Inanimate objects appearing alive (for example, walls that appear to be "breathing" or growing)
  • Intensified color
  • Objects appearing larger than they are (macropsia)
  • Objects appearing smaller than they are (micropsia)
  • Trails of images of moving objects
  • Visual snow or air that looks grainy or textured

Occasionally, people or situations may seem bizarre or ridiculous, or the person experiencing the flashback may feel dissociated. When this happens in a social situation requiring self-control, it can be embarrassing or scary for the person experiencing it.


Often diagnosed in people with a history of substance use, HPPD can occur even after the one-time use of triggering drugs, which include LSD, phencyclidine (PCP), methylenedioxymethamphetamine (MDMA), and cannabis (marijuana).

The following co-occurring mental illnesses are also common in people with HPPD but not required to make a diagnosis:

If you or someone you care about is experiencing intense and frequent flashbacks, you should visit your healthcare provider. It's important to be honest about your current and past drug use, as well as any history of mental illness.

Remember, the doctor is not there to judge you but to help you find the right treatment to ease your symptoms.

According to the American Psychiatric Association, to be diagnosed with HPPD a person must:

  • Experience effects of hallucinogens after cessation of hallucinogen use
  • Experience significant distress or impairment (in social, work-related, or other areas of life) because of the symptoms
  • Be generally aware that they are experiencing a drug-induced effect


Flashbacks can come on unpredictably or in response to a trigger, such as tiredness, anxiety, or stress. Triggered flashbacks can be especially difficult as the person may already be feeling vulnerable due to the trigger, which can make the out-of-control feeling of the flashback all the more confusing and upsetting.

The experience of a flashback can also be self-induced by the person thinking about the experience of tripping on a hallucinogenic drug.

While we don't know a lot about what causes HPPD, we do know what doesn't cause them, including the following:

  • Another condition such as schizophrenia or brain damage
  • Current hallucinogen intoxication
  • LSD being stored in the body and re-released

The only certain cause of HPPD is previous hallucinogen use. You cannot have HPPD if you've never used a hallucinogenic drug.


There are two types of HPPD:

  • Type 1: People experience random, brief flashbacks
  • Type 2: People experience ongoing vision changes that may come and go


Flashbacks usually subside on their own after the drug use has been discontinued, over the course of a few months, and most experts agree about the importance of abstaining from drug use for recovery.


A mental health professional can help to treat the anxiety that can accompany flashbacks, giving the person more of a sense of self-control.

If the person has no insight into the drug-induced nature of their symptoms or if these experiences persist or cause significant distress, however, they should seek a psychiatric assessment to determine if there is another mental health issue involved, such as psychosis.


Anti-seizure and epilepsy medicines like Klonopin (clonazepam) and Lamictal (lamotrigine) have been used in the treatment of HPPD, however, there is no recognized medical treatment for flashbacks.

Other drugs that have been studied in the treatment of HPPD include:


Having a flashback can be distressing, but calming or self-soothing activities like deep breathing, grounding techniques, and mindfulness can ease the psychological discomfort and help you to stay in the moment. It's also important to learn your triggers so you can do your best to avoid them and better manage them when they do occur.

For example, if stress is a trigger for you, work on practicing stress management. If fatigue is a trigger, take steps to get adequate sleep and rest when you need to.

A Word From Verywell

Whether you turn to a loved one or a mental health professional, know that you don't have to deal with HPPD and drug-related flashbacks alone. Getting help and seeking support is a great first step toward overcoming the disturbing and frequent visual disturbances of HPPD.

3 Sources
Verywell Mind uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. American Psychiatric Association. Diagnostic and Statistical Manual of Mental Disorders, fifth edition DSM-5. American Psychiatric Association, 2013.

  2. Martinotti G, Santacroce R, Pettorruso M, et al. Hallucinogen persisting perception disorder: Etiology, clinical features, and therapeutic perspectives. Brain Sci. 2018;8(3). doi:10.3390/brainsci8030047

  3. Hermle L, Simon M, Ruchsow M, Geppert M. Hallucinogen-persisting perception disorder. Ther Adv Psychopharmacol. 2012;2(5):199-205. doi:10.1177/2045125312451270

By Elizabeth Hartney, BSc, MSc, MA, PhD
Elizabeth Hartney, BSc, MSc, MA, PhD is a psychologist, professor, and Director of the Centre for Health Leadership and Research at Royal Roads University, Canada.