Major
citalopram × Mirtazapine
SSRI (selective serotonin reuptake inhibitor)×Other antidepressants (NaSSA)
Mechanism
Mirtazapine increases serotonergic transmission via α2-adrenergic blockade and blocks 5-HT2A/2C. Serotonin syndrome is rare with citalopram but possible at high doses. Citalopram itself prolongs QT.
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 used for antidepressant augmentation. Cap citalopram at 20 mg and mirtazapine at 30 mg/day. Monitor blood pressure, pulse, and mental status in the early weeks.
Check the full regimen, not just this pair
Opens the checker with these two drugs prefilled. Add the rest of the regimen and recompute additive risks.