What Is Hallucinogen Persisting Perception Disorder (HPPD)?

A person taking hallucinogenic drugs often expect the effects to disappear after the drug metabolizes through their system. On rare occasions, the visual symptoms can reappear weeks, months, or years after using hallucinogens. This condition is known as hallucinogen persisting perception disorder (HPPD), or as having flashbacks.

Two types of hallucinogen persisting perception disorder exist. Type-1 HPPD is characterized by non-distressing flashbacks that may appear days or months after using hallucinogens and may feel pleasurable or controllable. Type-2 HPPD involves visual abnormalities, like haloes or trails, that are pervasive, unpleasurable, and make someone feel anxious or disturbed.

While literature does not specify how long after a person using a hallucinogen may experience HPPD, the Diagnostic and Statistical Manual of Mental Disorder (DSM-5) states it is a rare condition that affects about 4.2% of people who have a history of hallucinogen use.

What Do Flashbacks Feel Like?

The flashbacks of HPPD are primarily visual and can make you feel as if you are reliving an experience from the past. Flashbacks are typically less intense and do not last as long as the effects you get when using hallucinogens. You may feel a dissociation or depersonalization from your situation during the flashback.

Flashbacks can make some people feel uneasy because they are unwanted and unexpected, interfering with your daily tasks. The lack of control over your flashbacks can lead to feelings of uneasiness, anxiety, depression, panic attacks, and migraines.

Symptoms Of HPPD

Specific symptoms will vary for each person, but examples of visual flashbacks include the following:

  • Objects appearing smaller or larger than they are
  • Seeing intense colors
  • Seeing halos or trails behind moving objects
  • Seeing floaters that move with your vision
  • Seeing objects that aren’t there
  • Seeing movement out of the corner of your eye that is not happening
  • Seeing inanimate objects come alive, like breathing or moving
  • Seeing what looks like snow or grainy air
  • Seeing geometric shapes or haloes

According to a systematic review published in Frontiers in Neuroscience, a rare symptom called the Alice in Wonderland perception occurs when someone feels their body change in size. Some refer to it as a form of micropsia or macropsia, meaning they see things smaller or larger than their actual size.

Secondary emotional symptoms are those that appear following visual disturbances. Examples include anxiety, confusion, irritability, depression, and panic attacks. Secondary symptoms can lead to the following immediate symptoms:

  • Shaking, shivering, or trembling
  • Increasing heart rate
  • Laborious breathing
  • Sweating
  • Feeling dizzy
  • Having chest pain
  • Feeling nausea
  • Feeling doom or dread

Causes Of Hallucinogen Persisting Perception Disorder

The exact cause of HPPD is not fully understood, and researchers continue to search for a definitive answer. Some reports state flashbacks occur due to how a person’s nervous system reacts to using hallucinogens. Some people may experience chronic disruptions in how unnecessary stimuli are filtered into the brain.

Another possible cause may be reverse tolerance or sensitization. Tolerance occurs when someone uses the same dose of a drug regularly, and over time, the drug’s effects decrease. To feel the desired effects, they must increase the drug dose. With HPPD, the theory is that using the same dose of hallucinogens regularly increases the effects rather than decreases them.

HPPD only occurs in those who have, at some point, taken a hallucinogenic drug. Research shows hallucinogens that cause HPPD include:

HPPD can have many triggers, including being tired, lacking sleep, and stress. For some, simply thinking about hallucinations can trigger a flashback.

Diagnosing Hallucinogen Persisting Perception Disorder

To receive a diagnosis of HPPD, you must meet the criteria set forth by the American Psychiatric Association. The criteria are in the DSM-5 and include:

  • Recurrence of hallucinogen-induced perceptual symptoms after you stop using hallucinogens.
  • Symptoms that create distress or impairment at work, home, school, or socially.
  • A current physical or mental health disorder that does not cause symptoms.

Questionaries and scales exist to help determine the presence and severity of HPPD. One is the Vividness of Visual Imagery Questionnaire (VVIQ), a scale that evaluates visual imagery by asking questions about vivid memories and discussing experiences as they are seen visually. Another is the Modified Tellegen Absorption Scale (MTAS), which assesses how open a person is to absorption, a personality trait that represents being prone to accepting fantasy as real. Lastly, the Visual Apophenia Luke Irvine Scale (VALIS) for HPPD uses cloud images to determine if people see images within the clouds and, if so, how vividly.

Treating HPPD

Some people may find they can manage flashbacks that are brief and not very intense. Those who experience flashbacks frequently and with higher intensity may need professional help, especially when the flashbacks are interfering with how they function in their daily routines.


Psychotherapy has been found to be beneficial in the treatment of HPPD, as a licensed therapist can teach and provide coping skills to help a person deal with HPPD symptoms. Beneficial therapies include:

Holistic Therapies

  • Deep breathing
  • Meditation
  • Grounding
  • Stress management

Behavioral Therapies


Research into treatment medications for HPPD is limited, but early data suggests that some medications can help calm an anxious mind and help eliminate the flashbacks associated with HPPD. One of these medications is clonidine, which helps block chemicals in the brain that trigger the sympathetic nervous system, resulting in lowered anxiety. Likewise, survey data discussed in Psychiatric Services shows that benzodiazepines (sedatives that help relax the mind) like Klonopin may also be beneficial in the treatment of HPPD.

Lifestyle Changes

There are lifestyle changes that can help with the management of HPPD, including:

  • Exercising to boost endorphins and other feel-good chemicals in the brain.
  • Limiting caffeine and alcohol that may cause a reaction in your body.
  • Getting quality, restorative sleep each night.
  • Prioritizing self-care.
  • Building a positive support network of peers who experience HPPD.

The most crucial step you can take to avoid HPPD is to stop misusing hallucinogens. If you aren’t able to stop using these drugs, help is available.

Find Treatment For Drug Addiction And Abuse

While hallucinogens are not generally addictive, experiencing negative consequences from frequent use can be an early sign of psychological dependence. Some people also use hallucinogens with other substances, leading to polydrug use and its many adverse effects.

If you are concerned about your frequent hallucinogen use or are experiencing the symptoms of HPPD, help is available. Contact a treatment provider today to learn more about your treatment options.