Although the goal of treatment for major depressive disorder is full remission, for most patients, remission is the exception rather than the rule. Carefully choosing medications with synergistic mechanisms of action at treatment initiation may increase rates of response and remission and decrease the risk for relapse. An agent such as folate, which is a naturally occurring B vitamin and is necessary for the synthesis of the trimonoamine neurotransmitters implicated in depression, may enhance the effects of a traditional antidepressant.