米氮平（英语：Mirtazapine），商品名为瑞美隆（Remeron），是一种去甲肾上腺素和特异性5-羟色胺能抗抑郁药 (NaSSA) ，主要用来治疗抑郁症。米氮平也经常被用作抗焦虑药，安眠药，止吐药和食欲促进剂。按分子结构分类时，米氮平被分类为四环类抗抑郁药(TeCA) ，并且为米安舍林的6-氮杂类似物。 米氮平也是一种外消旋混合物，包含(R)- 和 (S)-异构体.

Mirtazapine (brand names: Avanza, Axit, Calixta, Mirtaz, Mirtazon, Remeron, Zispin) is an atypical antidepressant with noradrenergic and specific serotonergic activity. It works by blocking the α₂ adrenergic auto- and heteroreceptors (enhancing serotonin release), and selectively antagonizing the 5-HT₂ and 5-HT₃ serotonin receptors in the central and peripheral nervous system. It also enhances serotonin neurotransmission at the 5-HT₁ receptor and blocks the histaminergic (H₁) and muscarinic receptors. Mirtazapine is not a serotonin or norepinephrine reuptake inhibitor but may increase serotonin and norepinephrine by other mechanism of action.