Hallucinogen persisting perception disorder

Hallucinogen persisting perception disorder (HPPD) is a disorder characterized by a continual presence of sensory disturbances, most commonly visual, that are reminiscent of those generated by the use of hallucinogenic substances. Previous use of hallucinogens by the person is necessary, but not sufficient, for diagnosis of HPPD. For an individual to be diagnosed with HPPD, the symptoms cannot be due to another medical condition. HPPD is distinct from flashbacks by reason of its relative permanence; while flashbacks are transient, HPPD is persistent. HPPD is a DSM-IV diagnosis with diagnostic code 292.89.