Table 2.

Case reports on HPPD treatment.

Author (year)	Drug	Sample size	Study design	Major results
Abraham [1983]	Benzodiazepines Phenothiazines	21	Observational study	8 of the 9 subjects receiving benzodiazepines reported a reduced intensity and frequency of visual disturbances, whereas 11 of 12 subjects receiving phenothiazines reported exacerbation of HPPD
Abraham and Mamen [1996]	Risperidone	3	Case reports	3 patients with HPPD treated with risperidone reported an exacerbation of LSD-like panic and visual symptoms
Lerner et al. [1997]	Naltrexone	2	Case reports	Dramatic improvement with naltrexone (50 mg daily) was reported in two young men with LSD-induced HPPD. The remission was sustained as it was possible to discontinue the naltrexone after 2 months without precipitating a relapse
Lerner et al. [2000]	Clonidine	8	Observational study	6 of the 8 subjects (2 dropped out) received clonidine (0.025 mg, three times a day) for 2 months which alleviated LSD-related HPPD
Lerner et al. [2001]	Clonazepam	2	Case reports	2 outpatients with LSD-induced HPPD were successfully treated with clonazepam. They had not responded to low doses of classic antipsychotics or low-potency benzodiazepines
Lerner et al. [2002a]	Reboxetine	1	Case report	During a 6-month follow-up period on reboxetine (6mg/day) no exacerbations of visual disturbance were reported
Lerner et al. [2003]	Clonazepam	16	Observational study	16 patients received clonazepam 2 mg/day for 2 months. Patients reported significant relief during clonazepam administration.This improvement persisted during a 6-month follow-up period
Espiard et al. [2005]	Olanzapine Risperidone Sertraline	1	Case report	A case of a young man presenting with HPPD after a mixed intoxication with psilocybin and cannabis. Olanzapine (5 mg) exacerbated symptoms and was replaced by risperidone (2 mg/day) and sertraline (150 mg/day). After 6 months of this treatment HPPD disappeared

HPPD, hallucinogen-persisting perception disorder; LSD, lysergic acid diethylamide.