Augmentation and combination strategies for complicated depression.

Approximately half of patients with depression do not respond or only partially respond to first-line antidepressant monotherapy. To enhance treatment response, the treating clinician may choose to augment the antidepressant with a nonantidepressant agent or combine the initial antidepressant with another antidepressant, typically of another class. Although the augmentation and combination strategies reviewed here appear relatively safe and effective, additional controlled studies are needed to compare these treatment options, guide treatment selection for individual patients, and answer questions regarding the duration of combination or augmentation strategies for patients with treatment-resistant depression.