Haloperidol × Quetiapine

Dual antipsychotic therapy – additive risk of extrapyramidal symptoms, sedation, QT prolongation, and metabolic side effects. Polypharmacy without therapeutic rationale in most cases.

Sedation, extrapyramidal symptoms (tremor, rigidity, akathisia), QT prolongation on ECG. Metabolic effects: weight gain, dyslipidaemia (from quetiapine).

Avoid the combination. Choose one antipsychotic: quetiapine for schizophrenia with anxious-depressive component or bipolar disorder; haloperidol for acute psychotic agitation. If dual therapy is needed, restrict to short-term use during acute psychotic episodes.