Wellbutrin is an antidepressant medication classified as a norepinephrine and dopamine reuptake inhibitor (NDRI). It works by affecting the chemical messengers norepinephrine and dopamine in the brain to help improve symptoms of depression. It is used to treat major depressive disorder (MDD) and seasonal affective disorder (SAD) but is not a selective serotonin reuptake inhibitor (SSRI) or serotonin-norepinephrine reuptake inhibitor (SNRI). It is chemically distinct from many other antidepressants and is known for having fewer sexual side effects and less weight gain compared to other antidepressants.