Trade names Prozac™, Sarafem™, Fontex™ etc.
Fluoxetine is a Selective Serotonin Reuptake Inhibitor (SSRI) used in the treatment of major depression, OCD etc.
SSRIs are believed to act by inhibiting the reuptake of serotonin after being released in the brain synapses. The exact mechanism for its operation is unknown.
Quote from prescribing information datasheet for Prozac™, from manufacturer Eli Lilly and Company. source
“Although the exact mechanism of PROZAC is unknown, it is presumed to be linked to its inhibition of CNS neuronal uptake of serotonin.”
Further, the theory that manipulating serotonin levels may help in treatments is also unproven. See : Serotonin and Depression, PloS Medicine 2005 source
“…there exists no rigorous corroboration of the serotonin theory, and a significant body of contradictory evidence.”