Moderate
Probable
Description
Concurrent fluoxetine and lithium may increase serotonin syndrome risk; fluoxetine may also alter lithium pharmacokinetics in some patients.
Mechanism
Lithium potentiates serotonin release; fluoxetine inhibits SERT-mediated reuptake, leading to additive serotonergic stimulation.
Clinical Significance
Clinical case series describe serotonin syndrome with this combination; the interaction is also used therapeutically under supervision.
Management
Monitor lithium levels and watch for serotonin toxicity symptoms; consider dose reduction if signs emerge.