Some selective serotonin reuptake inhibitor (SSRI) antidepressants, such as Paxil (Paroxetine), reduce tamoxifen’s effectiveness by inhibiting its bioactivation by cytochrome P450 2D6 (CYP2D6). Paroxetine use during tamoxifen treatment is associated with an increased risk of death from breast cancer, supporting the hypothesis that paroxetine can reduce or abolish the benefit of tamoxifen in women with breast cancer.
