LSD-induced Hallucinogen Persisting Perception Disorder treated with clonazepam: two case reports

Isr J Psychiatry Relat Sci. 2001;38(2):133-6.


Benzodiazepines are recommended for the treatment of Hallucinogen Persisting Perception Disorder (HPPD), although it is unclear which may be more helpful. Two out-patients with LSD-induced HPPD were successfully treated with clonazepam. They had not responded to low potency benzodiazepines or low doses of classic antipsychotics. After clonazepam discontinuation they reported a marked improvement and only mild symptomatology which persisted during a six month follow-up period. High potency benzodiazepines like clonazepam, which has serotonergic properties, may be superior to low-potency benzodiazepines in the treatment of some patients with LSD-induced HPPD.

Publication types

  • Case Reports

MeSH terms

  • Adult
  • Clonazepam / therapeutic use*
  • Dose-Response Relationship, Drug
  • Drug Administration Schedule
  • Follow-Up Studies
  • Humans
  • Lysergic Acid Diethylamide / adverse effects*
  • Male
  • Perceptual Disorders / chemically induced*
  • Perceptual Disorders / drug therapy
  • Substance Withdrawal Syndrome / drug therapy*


  • Clonazepam
  • Lysergic Acid Diethylamide