Mirtazapine is a noradrenergic and specific serotonergic antidepressant (NaSSA) primarily used for the treatment of major depressive disorder (MDD). It works by enhancing the activity of norepinephrine and serotonin in the brain, which helps regulate mood and alleviate symptoms of depression. Unlike selective serotonin reuptake inhibitors (SSRIs), mirtazapine blocks alpha-2 adrenergic receptors, leading to increased release of these neurotransmitters. Additionally, it has strong histamine H1 receptor antagonism, which contributes to its sedative effects. This makes it particularly beneficial for individuals with depression-related insomnia, anxiety, or appetite loss, as it helps improve sleep quality, reduce anxiety, and stimulate appetite.

One of the key advantages of mirtazapine is its fast onset of action, often showing improvements in sleep and mood within the first week of treatment. It is generally well-tolerated, but common side effects include drowsiness, increased appetite, and weight gain, due to its antihistaminergic properties. Unlike SSRIs and serotonin-norepinephrine reuptake inhibitors (SNRIs), mirtazapine has a lower risk of sexual dysfunction, making it a preferred option for some patients. However, it may cause dizziness, dry mouth, and occasional daytime sedation, which should be monitored. Despite these considerations, mirtazapine remains an effective and widely used antidepressant, particularly for patients with sleep disturbances, appetite issues, or treatment-resistant depression, providing comprehensive symptom relief and improved overall well-being.