Medicine:Hallucinogen persisting perception disorder

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Hallucinogen persisting perception disorder
HPPD noise simulation, often referred to as visual snow

Hallucinogen persisting perception disorder (HPPD) is a chronic and non-psychotic disorder in which a person experiences apparent lasting or persistent visual hallucinations or perceptual distortions after a previous hallucinogenic drug experience, usually lacking the same feelings of intoxication or mental alteration experienced while on the drug. The hallucinations and perceptual changes themselves are usually not intense or impairing and consist of visual snow, trails and after images (palinopsia), light fractals on flat surfaces, intensified colors or other psychedelic visuals. People who have never previously taken drugs have also reported some visual anomalies associated with HPPD (such as floaters and visual snow).[1][2]

To be diagnosed, the disorder must cause distress or impairment in work or everyday life.[3] Symptoms often get worse when focused on.[citation needed]


In 1898, the English writer and intellectual Havelock Ellis reported a heightened sensitivity to "the more delicate phenomena of light and shade and colour" for a prolonged period of time after consuming the psychedelic drug mescaline. This may have been one of the first recorded cases of what would later be called "HPPD".[4] However, mild residual effects or "afterglows" from these types of drugs are not necessarily unusual nor indicative of what can be classified as a disorder like HPPD since distress to the individual is usually a requirement for diagnosis.[3]

HPPD subtypes

According to a 2016 review, there are two theorized subtypes of the condition.[5] Type 1 HPPD is where people experience random, brief flashbacks.[3] Type 2 HPPD entails experiencing persistent changes to vision, which may vary in intensity.[3] This model has faced scrutiny however due to "flashbacks" often being considered a separate affliction and not always a perceptual one.


HPPD is not related to psychosis due to the fact those affected by the disorder can easily distinguish their visual disturbances from reality.[6] The only certain cause of HPPD is prior use of hallucinogens. Some evidence points to phenethylamines carrying a slightly greater risk than lysergamides or tryptamines. There are no known risk factors, and what might trigger any specific disturbing hallucination is not known.[3] Some sort of disinhibition of visual processing may be involved.[7] It has been suggested MDMA (ecstasy) use with other drugs is linked to the development of HPPD.[8]


HPPD is a DSM-5 diagnosis with diagnostic code 292.89 (F16.983).[3] For the diagnosis to be made, other psychological, psychiatric, or neurological conditions must be ruled out and it must cause distress in everyday life.[3]


As of June 2021 there is still no good evidence of any specific medicinal treatment as being commonly effective for HPPD.

Avoiding any additional use of psychoactive drugs (including cannabis and alcohol) from an early stage of the disorder seems to be an effective way for many sufferers to achieve recovery, as these substances apparently worsen the condition over time.[citation needed]

Some prescription drugs (lamotrigine, clonazepam, levetiracetam and others) have been known to relieve symptoms for some, but worsen symptoms or create dependencies for others.[citation needed]

Antipsychotic drugs and SSRIs have also been reported to help some people temporarily but worsen symptoms for others.[citation needed]

Some sufferers have reported benefits from prolonged water fasting, medications like acetylcysteine and lithium, and from supplements like tyrosine, ashwagandha and lion's mane, although some users report lion's mane and ashwagandha as having potentially negative effects or creating dependencies.[citation needed]

Sunglasses and talk therapy might also help those who are dealing with HPPD, but in general it seems that maintaining sobriety from all psychoactive substances is still the best solution available for this condition.


The prevalence of HPPD was unknown as of 2018.[citation needed] Estimates in the 1960s and 1970s were around 1 in 20 for intermittent HPPD among regular users of hallucinogens. In a study of psychedelic users, 23.9% reported constant HPPD-like effects, however only 4.2% considered seeking treatment due to the severity.[9] It is not clear how common chronic HPPD may be, but one estimate in the 1990s was that 1 in 50,000 regular users might have chronic hallucinations.[3]

Society and culture

In the second episode of the first season of the 2014 series True Detective ("Seeing Things"), primary character Rustin Cohle (Matthew McConaughey) is depicted as having symptoms similar to HPPD such as light tracers as a result of "neurological damage" from substance use.[10]

American journalist Andrew Callaghan, former host of the internet series All Gas No Brakes, revealed during a 2021 interview with Vice News that he has a HPPD diagnosis as a result of excessive psilocybin use at a young age. Describing his symptoms, he noted that he experiences persistent visual snow and palinopsia.[11]


  1. Zobor, Ditta; Strasser, Torsten; Zobor, Gergely; Schober, Franziska; Messias, Andre; Strauss, Olaf; Batra, Anil; Zrenner, Eberhart (2015). "Ophthalmological assessment of cannabis-induced persisting perception disorder: Is there a direct retinal effect?". Documenta Ophthalmologica 130 (2): 121–130. doi:10.1007/s10633-015-9481-2. PMID 25612939. 
  2. Krebs, Teri S.; Johansen, Pål-Ørjan (2013). "Psychedelics and Mental Health: A Population Study". PLOS ONE 8 (8): e63972. doi:10.1371/journal.pone.0063972. PMID 23976938. 
  3. 3.0 3.1 3.2 3.3 3.4 3.5 3.6 3.7 Halpern, JH; Lerner, AG; Passie, T (2018). "A Review of Hallucinogen Persisting Perception Disorder (HPPD) and an Exploratory Study of Subjects Claiming Symptoms of HPPD.". Current Topics in Behavioral Neurosciences 36: 333–360. doi:10.1007/7854_2016_457. ISBN 978-3-662-55878-2. PMID 27822679. 
  4. "When the Trip Never Ends". 
  5. Halpern, John H.; Lerner, Arturo G.; Passie, Torsten (2016). "A Review of Hallucinogen Persisting Perception Disorder (HPPD) and an Exploratory Study of Subjects Claiming Symptoms of HPPD". Behavioral Neurobiology of Psychedelic Drugs. Current Topics in Behavioral Neurosciences. 36. pp. 333–360. doi:10.1007/7854_2016_457. ISBN 978-3-662-55878-2. 
  6. Bogenshutz, M.P ., & Ross, S. (2018). "Therapeutic Applications of Classic Hallucinogens". Current Topics in Behavioral Neuroscience. 
  7. G Lerner, A; Rudinski, D; Bor, O; Goodman, C (2014). "Flashbacks and HPPD: A Clinical-oriented Concise Review.". The Israel Journal of Psychiatry and Related Sciences 51 (4): 296–301. PMID 25841228.  open access
  8. Litjens, Ruud P. W.; Brunt, Tibor M.; Alderliefste, Gerard-Jan; Westerink, Remco H. S. (August 2014). "Hallucinogen persisting perception disorder and the serotonergic system: a comprehensive review including new MDMA-related clinical cases". European Neuropsychopharmacology 24 (8): 1309–1323. doi:10.1016/j.euroneuro.2014.05.008. ISSN 1873-7862. PMID 24933532. 
  9. Baggott, M.J.; Coyle, J.R.; Erowid, E.; Erowid, F.; Robertson, L.C. (2011-03-01). "Abnormal visual experiences in individuals with histories of hallucinogen use: A web-based questionnaire" (in en). Drug and Alcohol Dependence 114 (1): 61–67. doi:10.1016/j.drugalcdep.2010.09.006. ISSN 0376-8716. PMID 21035275. 
  10. Fukunaga, Cary Joji, 1977- Cuddy, Carol. Pizzolatto, Nic, 1975- McConaughey, Matthew, 1969- Harrelson, Woody. Monaghan, Michelle. Potts, Michael (Performer) Arkapaw, Adam. Hall, Alex (Film editor) Burnett, T-Bone., True detective., OCLC 964500128 
  11. Documenting America's Underbelly - ALL GAS NO BRAKES (video). Vice. January 21, 2021. 20:48-21:49 minutes in. Retrieved January 24, 2021.

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