Serious adverse effects such as acute psychoses have been reported following treatment with chloroquine. Chloroquine can cause cell death, including neurons. We aimed to identify the most frequent type of psychiatric manifestation and symptomatological characteristics of psychosis following chloroquine ingestion (PFC).

Out of a total of 4471 randomly selected recent-onset psychosis patients, 3610 consecutive patients who had responded to standard treatment were screened for entry in the study. We compared background clinicodemographic profile information and psychopathology of 51 PFC patients, who were either drug free or drug naive, to 51 brief psychotic disorder (BPD) patients who were matched in terms of age, sex and education. Only those patients who remitted within 8weeks (PFC patients) or 4weeks (BPD patients) were included. Cranial computed tomography, electroencephalography and lumbar puncture of the entire experimental group were normal, and none had Mini Mental Status Examination score <22. Group difference and correlational statistics (parametric and nonparametric) have been used to test the hypotheses and explain the results.

The most common (76.2%) type of psychiatric disturbance in PCF group was mood disorder (mixed episode) accompanied by predominant irritability with little blunting of affect. PFC patients characteristically had prominent positive symptoms with visual hallucination and derealization experiences. They were more restless, agitated and anxious and had more disturbed thought content and orientation, but better preserved insight. There was no linear relationship between the amount of chloroquine consumed and the severity of psychosis.

Considering the large number of patients still receiving chloroquine especially in developing countries, this study has been presented to draw attention of the psychiatrists and other health professionals to the hazardous effect of chloroquine on mental health.