Mirtazapine (Remeron, Avanza, Zispin) is a noradrenergic and specific serotonergic antidepressant (NaSSA) which was introduced by Organon International in the United States in 1990 and is used primarily in the treatment of depression. It is also commonly used as an anxiolytic, hypnotic, antiemetic, and appetite stimulant. Structurally, mirtazapine can also be classified as a tetracyclic antidepressant (TeCA).

Mirtazapine's primary use is the treatment of major depressive disorder and other mood disorders.

However, it has also been found useful in alleviating the following conditions and may be prescribed off-label for their treatment:

Mirtazapine has had a solid amount of literature published on its efficacy (or in some cases lack thereof) in the experimental treatment the following conditions:

In clinical studies, mirtazapine has been found to be an effective antidepressant with a generally tolerable side effect profile relative to other antidepressants.

In a major systematic review published in 2009 which compared the efficacy and tolerability of 12 popular antidepressants, mirtazapine was found to be superior to all of the included selective serotonin reuptake inhibitors (SSRIs) and serotonin-norepinephrine reuptake inhibitors (SNRIs), and reboxetine, bupropion, and mianserin in terms of antidepressant efficacy, while it was average in regards to tolerability. However, it is important to note that the efficacies of most of the antidepressants in this review differed only slightly. Hence, the apparent superiority of mirtazapine relative to most of the others included may not actually be all that prominent or significant in this case.