Hallucinogen persisting perception disorder

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

Hallucinogen persisting perception disorder (HPPD) is a chronic (and often permanent) disorder in which a person has flashbacks of visual hallucinations or distortions experienced during a previous hallucinogenic drug experience, usually lacking the same feelings of mental intoxication experienced before. Hallucinations are usually not intense or impairing and consist of visual snow, light fractals on flat surfaces or other psychedelic visuals. To be diagnosed, the disorder must cause distress or impairment in work or everyday life.[1] The flashbacks may be continuous or just occasional.[1] Symptoms often get worse when focused on.

HPPD subtypes[edit]

According to a 2016 review, there are two subtypes of the condition:[2]

Type 1 HPPD[edit]

This is where people experience HPPD in the form of random, brief flashbacks.

Type 2 HPPD[edit]

People with this kind of HPPD experience ongoing changes to their vision, which may vary in intensity.


The only certain cause for 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.[1] Some sort of disinhibition of visual processing may be involved.[3]


HPPD is a DSM-5 diagnosis with diagnostic code 292.89 (F16.983).[1] For the diagnosis to be made, other psychological, psychiatric, or neurological conditions must be ruled out and it must cause distress in everyday life.[1]


As of 2018 there was no good evidence for any treatment. For people diagnosed with chronic HPPD, sunglasses and therapy might help. Antipsychotic drugs and SSRIs have been reported to help some people and worsen symptoms for others. In general anecdotal reports point to sedatives being helpful and stimulants and cannabis potentiating symptoms.


The prevalence of HPPD was unknown as of 2018. Estimates in the 1960s and 1970s were around 1 in 20 for intermittent HPPD among regular users of hallucinogens. It is not clear if chronic HPPD exists, but one estimate in the 1990s was that 1 in 50,000 regular users might have chronic hallucinations.[1]

In popular culture[edit]

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 HPPD symptoms such as light tracers as a result of "neurological damage" from substance use.[4]


  1. ^ a b c d e f 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.
  2. ^ 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. PMID 27822679.
  3. ^ 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
  4. ^ 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 964500128CS1 maint: multiple names: authors list (link)

External links[edit]

External resources