HPPD – A Very Brief Summary based on Halpern, Lerner & Passie (2016)

by Eric M. Fortier, B.A. | May 2017

Hallucinogen Persisting Perceptual Disorder (HPPD) is included in the DSM-5 as a clinical diagnosis and psychedelics are only one of the few known probable causes of HPPD. Symptoms have been found to occur in otherwise healthy normal populations. There are two recognized classifications of HPPD: Type 1, which are brief “flashbacks,” and Type 2 claimed to be chronic, waxing, and waning over months to years. It therefore might be valuable to reformulate how HPPD is defined according to symptoms, commonly including: difficulty with light accommodation, difficulty concentrating, halos/auras, floaters, difficulty communicating, afterimages, trails, tinnitus, visual snow, head pressure, ghosted afterimage, and swaying/moving stationary objects.

HPPD is more common in recreational users than in clinical populations, where it is virtually non-existent (Johnson 2008). Some factors were found predicting occurrence of HPPD, including pre-existing tinnitus, “floaters,” and trouble concentrating, but most importantly, anxiety and panic reactions during the experience. This has led to speculation on hallucinogen-induced PTSD symptomatology as a useful model for HPPD. An alternative view proposes HPPD may represent a worsening of pre-existing visual sensitivity.

Cannabis, MDMA, stimulants, and antipsychotics have been reported to potentially worsen symptoms of Type 2 HPPD, while psychotherapy, sedative-hypnotics, opioids (and opioid antagonists), clonidine, and sunglasses have been reported to potentially ameliorate symptoms. Not mentioned in this review is the potential for Lion’s Mane often anecdotally credited for treating symptoms of HPPD. Reducing the frequency and duration of the panic reactions during the experience reduce the likelihood of developing symptoms of HPPD. Regular mindfulness meditation practice appears to negatively predict anxious and panic reactions during the psychedelic state, as does the presence of a trusted, calming, non-judgemental guide.

Sample: 2000, mostly white men ~30 yrs. (40% were daily cannabis users, 30% tobacco smokers)
Questionnaires: Hallucinogen Rating Scale (HRS) and MEQ-30

The scary stuff
Of all reported bad trips,

  • “10.7% reported putting themselves or others at risk of physical harm”

correlated with: estimated dose, degree of difficulty, and duration of experience
anti-correlated: physical comfort, social support

  • “2.6% reported behaving in a physically aggressive or violent manner towards themselves or others”
  • “2.7% reported getting help at a hospital or emergency department during the chosen occasion”
  • “20% of sought treatment for enduring psychological symptoms like fear, anxiety, depression, paranoia and others, which lasted no longer than a week in 75% of respondents, but lasted over a year in 10%.”
  • Increased suicidality in 5/2000 (0.25%)

Less scary stuff

  • Decreased suicidality in 6/2000 (0.3%)
  • “a population survey has indicated protective effects of lifetime psilocybin exposure and psychological distress and suicidality (Hendricks et al., 2015).”
  • Personal meaning (and spiritual significance and subsequent well-being) correlated with the difficulty of the experience, but were anti-correlated with the length of the negative experience [i.e. best to shorten it when possible]

Conducive to positive experiences:

  • emotional state (76%) before taking psilocybin
  • physical comfort and safety of surroundings (75%)
  • social support and trust for others physically present (65%)

Most effective strategies used to help stop challenging experience
(from most to least effective):

  • calming your mind [e.g. meditating]
  • changing location, music, or social environment
  • and asking for help from a friend
  • smoking cannabis was reported to help ~50% the time, yet the opposite is often the case. [why? High THC/CBD ratio or dose? Paranoia? CNS activity? Psychotic-like reaction? Predispositions? Setting? Stigma/legality of cannabis use?]

Enter your email to receive an update when something new is posted.


Halpern, J. H., Lerner, A. G., & Passie, T. (2016). A Review of Hallucinogen Persisting Perception Disorder (HPPD) and an Exploratory Study of Subjects Claiming Symptoms of HPPD. In A. Halberstadt, D. Nichols, F. X. Vollenweide (Eds), Behavioral Neurobiology of Psychedelic Drugs (pp. 333-360). doi:10.1007/7854_2016_457

Johnson, M., Richards, W., & Griffiths, R. (2008). Human hallucinogen research: Guidelines for safety. Journal of Psychopharmacology, 22(6), 603-620. doi:10.1177/0269881108093587