Fluoxetine is an oral antidepressant medication prescribed for the treatment of major depressive disorder (MDD), obsessive compulsive disorder (OCD), panic disorder, bulimia nervosa, and premenstrual dysphoric disorder (PMDD). It may also be prescribed in combination with another medication called olanzapine in order to treat manic depression caused by bipolar disorder. The prescribed daily dose ranges greatly depending on what it is treating.