We hypothesize that the inhibition of CYP2D6 increased the concentration and side effects of venlafaxine (hyponatremia; additionally associated with the inhibition of CYP3A4), mianserin (restless legs syndrome (Hoque, 2020)), and paroxetine (gynecomastia/mastalgia (Damsa et al., 2003)). This evidence concerns the gene CYP2D6 and mastodynia.