How to Fix a Bad Trip? Hallucinogen Persistent Perception Disorder Treatment in Review
BJPsych Open June 1, 2026 Aleeha Batool, Chaitanya Morey
Hallucinogen Persistent Perception Disorder (HPPD) involves recurring perceptual symptoms after hallucinogen use stops, causing significant impairment. Diagnosis is difficult due to poor understanding and comorbid conditions, leading to low documented incidence. No established treatment guidelines exist. This review of 34 studies finds that α2 adrenergic agonists (especially clonidine) and benzodiazepines (especially clonazepam) may reduce distress and anxiety. Anti-epileptic drugs (particularly lamotrigine) have shown good response for perceptual symptoms in case reports. Antipsychotic agents worsened perceptual symptoms. Combination therapy with olanzapine and fluoxetine or risperidone and escitalopram showed improvement in two cases, but selective serotonin reuptake inhibitors alone did not. Neuromodulation (transcranial direct current stimulation and repetitive transcranial magnetic stimulation) showed sustained responses in two case reports. The evidence base is weak, and larger studies are needed.