Major
citalopram × duloxetine
SSRI (selective serotonin reuptake inhibitor)×SNRI
Mechanism
SSRI + SNRI – serotonergic load rises, serotonin syndrome risk. Duloxetine also prolongs QT at high doses, summing with citalopram's QT effect.
Symptoms
Serotonin syndrome: agitation, confusion, tremor, myoclonus, hyperreflexia. Autonomic features: sweating, tachycardia, hypertension, fever. First signs appear within hours of co-administration.
Management
The combination is not prescribed. When switching antidepressants, allow a 2-week washout. Alternative monotherapy: mirtazapine or agomelatine.