Major
fluvoxamine × Mirtazapine
SSRI×Other antidepressants (NaSSA)
Mechanism
Serotonergic load from combining two drugs with different mechanisms. Fluvoxamine also blocks CYP1A2 (a minor mirtazapine metabolic route); mirtazapine levels may rise.
Symptoms
Serotonin syndrome: agitation, confusion, tremor, myoclonus, hyperreflexia. Autonomic features: sweating, tachycardia, fever.
Management
The combination is used for augmentation in resistant depression ('California rocket fuel'). Keep doses low: mirtazapine 15–30 mg, fluvoxamine 100 mg/day. Monitor 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.