HPPD

Hallucinogen Persisting Perception Disorder 

Hallucination persisting perception disorder (HPPD) is a condition where people experience distressing, lingering changes to their perception after using drugs, commonly classical psychedelic drugs, such as LSD and psilocybin.

Because HPPD is relatively under-reported and under-researched, we still don't know a huge deal about HPPD. However, based on the existing evidence, we've collaborated with the Perception Restoration Foundation to create a comprehensive overview of HPPD so you can better understand the why and how of the condition and consider the different treatments and support. 

What is HPPD?

The DSM-5 criteria for HPPD are as follows:

  • Re-experiences of phenomena necessarily experienced under the influence of hallucinogens 

  • That these changes must be linked substantively to the use of hallucinogenic drugs

  • That these changes cannot be linked to other causes implicated in perceptual change, like schizophrenia or head injuries

  • That these changes create distress

By definition, this criteria means that somebody can have ongoing perceptual changes following drugs without having HPPD if the continuous hallucinations don't cause them distress. 

In scientific literature, HPPD is split into two categories:

  • Type 1: Perceptual changes occur in episodic and temporary flashbacks

  • Type 2: Perceptual changes appear as a regular feature of everyday perception, which can vary according to specific triggers

Because there is little research into HPPD, it's unclear how common it is. A 2011 survey of 2,445 psychedelic users on Erowid found that up to three-fifths of users reported lingering changes. However, changes were only permanent in 25% users and distressing in 4.2%. 

 Symptoms and Signs of HPPD

 Although HPPD is a complex condition, there are some common visual perceptual changes that users share:

  • Visual snow: When the visual field is coated with small, grainy dots like the static of an undialed TV 

  • 'Haloes': When objects have a bright 'halo' or 'aura' ring around them

  • 'Trails': When an object moves, a trail of faint replicated images follows it 

  • ‘After-images': When the outline or silhouette of an object is seen on a surface after looking away

  • Intensified 'floaters': Most of us have seen 'floaters', which are the small squiggly lines and shapes that sometimes appear in our vision. With HPPD, these floaters can become more visible, disturbing, and irritating

  • Assorted psychedelic-style effects: fractal kaleidoscopic patterns, faces, 'breathing' walls, moving, 'wavy' or shaky text, or flashing and strobing lights 

There are also non-visual changes associated with HPPD, including auditory changes (e.g., tinnitus), physical effects (e.g., increased pressure and pain to different body areas), and confused and unclear thoughts.

HPPD is commonly associated with Depersonalisation/Derealisation Disorder (DP/DR) - a condition in which people feel detached from their bodies and the world stops feeling real. 

Many people with HPPD also experience anxiety and depression, and in some cases, suicidal thoughts. 

Anxiety and depression may arise because of underlying conditions that a psychedelic experience can trigger. However, they may also occur because of the struggles associated with living with HPPD, such as:

  • The disruptive impact of perceptual changes can have on everyday life

  • Fear that changes will never go away

  • The constant reminder of a challenging experience 

  • Feelings isolated and lonely 

 How is HPPD Treated? 

Because the causes or neurobiology of HPPD isn't fully understood, there are no clear guidelines on how to treat the disorder. 

Psychological treatments

The primary response is to address the distress associated with the perceptual changes, which includes learning not to fixate or obsess on the changes and cultivating an attitude of acceptance. Acceptance and Commitment Therapy (ACT), mindfulness meditation and yoga are methods people can use to help increase acceptance of their condition. 

Working with a counsellor and therapist can also help people to adopt healthier thought patterns and behaviours to help manage any depressive or anxious comorbidities. 

Psychedelic integration therapy can also help people with HPPD make sense, re-address and start to make sense of the experience that triggered their disorder. 

Pharmacological treatments

Researchers have found that certain medications have been useful at helping improve HPPD symptoms in some cases. However, because of the small study sample sizes, the evidence for the use of these drugs isn't very strong. Furthermore, these drugs come with their own risks and, in some cases, can worsen HPPD symptoms or a person's quality of life. 

Studied medications for HPPD include:

  • Lamotrigine (anti-epilepsy drug): Case reports and anecdotal reports in online forums suggest that the drug can be useful 

  • Reboxetine (antidepressant): Case report suggests no deterioration of symptoms, while an improvement in comorbid depression

  • Clonazepam (benzodiazepine): Shown to be successful among 18 patients.

  • Naltrexone (opiate receptor blocker): Two patients experienced dramatic improvement. 

  • Risperidone (antipsychotic): Mixed results, some exacerbated, others improved. 

Practical approaches

People may also adopt practical approaches to help blunt some of the visual hallucinations associated with their disorder, such as: 

  • Wearing tinted sunglasses

  • Avoiding isolation in enclosed environments - as narrowing the field of vision can raise the intensity of symptoms

  • Avoiding dark environments

  • Utilising 'dark-mode' when using a computer

Because taking psychoactive drugs, even single experiences can intensify symptoms of HPPD, people with HPPD are strongly recommended to abstain from all psychoactive drugs, in particular cannabis. 

 What Causes HPPD?

Which drugs cause HPPD? 

Most of the drugs associated with HPPD onset are classic psychedelics, such as LSD, ayahuasca, psilocybin, 2C-B and salvia.

However, reports have highlighted that other psychoactive drugs which aren't classically psychedelic, such as MDMA, ketamine, and cannabis, can onset HPPD. Furthermore, certain medications have elicited HPPD-style changes, including antidepressants, antibiotics, and antipsychotics. 

Biological explanations

One theory of why psychedelics cause visual hallucinations is that they stop information incoming into the visual cortex from being filtered out. In turn, this causes visual 'noise' to appear in people's visual fields. In HPPD, the filtering mechanism may remain switched off even after the drug has worn off.

Another reason HPPD may occur is because of neuroplasticity. When people take psychedelics, their brain circuits become easier to change. In HPPD, it's possible that the ongoing altered perception brain is caused by the brain re-wiring during a psychedelic experience and not returning to it's pre-drug state

The neuroplasticity theory may explain why teenagers are more susceptible to HPPD, as their brains are more plastic than adults. This theory could also explain why sometimes HPPD can be resolved or decreased by having another psychedelic experience. 

Genetic factors may also mean certain people are more susceptible to HPPD than others. 

Psychological explanations

Psychedelics can sometimes bring to the surface suppressed psychological material, such as hidden memories of traumatic events. 

The psychedelic researcher Stanislav Grof believed HPPD occurs when suppressed material arises during a psychedelic experience and isn't properly processed. He, therefore, treated his HPPD patients by guiding them into a psychedelic state so their unprocessed traumas and memories could re-surface and be resolved. 

Because HPPD more often occurs following particularly challenging psychedelic experiences or 'bad trips', the ongoing reminder of the experience can be a significant factor in contributing to the distressing aspect of HPPD.

Support for HPPD

If you're somebody suffering from HPPD, remember that you're not alone, and you can find several online communities of people experiencing similar problems, including:

There are also support groups specifically for those experiencing visual snow, such as:

You may find it helpful to check out the Fireside Project helpline, a charity organisation offering free and immediate peer support for those experiencing difficulties related to psychedelics.

The Perception Restoration Foundation

The making of this webpage is courtesy of The Perception Restoration Foundation. 

The Perception Restoration Foundation (PRF) is an industry-funded 501 nonprofit. Its mission is to raise funds for studies and increase awareness around HPPD at all levels, in order to discover better treatments, increase clinical understanding, find a possible cure, and ensure a harm-reduction framework for the burgeoning 'psychedelic renaissance' in mental health treatments. 

Thanks to its fundraising efforts, the PRF has secured two breakout studies into HPPD, including using advanced brain imaging techniques to look deep in the brains of patients to try and understand HPPD's possible neurophysiological mechanism and using psychophysics to test for HPPD and subclinical symptoms that could develop into HPPD in the future.

If you're somebody with HPPD and would like to help out in an online survey study to understand the nature of HPPD experiences, please visit this page. 

A PRF-produced documentary on HPPD, Living In A Distorted World, will be released later this year. You can see the trailer here.