Mirtazapine is primarily used to treat major depressive disorder and other mood disorders. [19][20] Appears to act more rapidly than some selective serotonin reuptake inhibitors and similar to tricyclic antidepressants. [10][21]

In 2010, the National Institute for Health and Care Excellence recommended generic selective serotonin reuptake inhibitors as a first-line option because they are “as effective as other antidepressants and have a favorable risk-benefit ratio.” [22] About rice mirtazapine, it found: "Mirtazapine did not differ from other antidepressants on any measure of efficacy, although mirtazapine appeared to have a statistical, but not clinical, advantage in achieving remission. Furthermore, mirtazapine was not superior in Statistically superior to selective serotonin reuptake inhibitors in reducing depressive symptoms, but the difference was not clinically meaningful. However, there is strong evidence that patients taking mirtazapine are less likely to leave treatment early because of side effects , although patients who reported side effects or left treatment early did not for any reason.[23]

A 2011 Cochrane review comparing mirtazapine with other antidepressants found that while mirtazapine had a faster onset of action (measured at two weeks) in the people it was Its efficacy is about the same as that of other antidepressants.