Widely used as an active pharmaceutical ingredient in antidepressant medications, it is primarily prescribed to treat major depressive disorder, obsessive-compulsive disorder, panic disorder, and bulimia nervosa. It works by increasing serotonin levels in the brain, which helps improve mood, sleep, appetite, and energy levels. Additionally, it is sometimes used off-label for conditions like post-traumatic stress disorder and premenstrual dysphoric disorder. Its effectiveness and relatively mild side effect profile have made it a common choice in psychiatric treatment.