Key takeaways
Mirtazapine (Remeron) and fluoxetine (Prozac) are both used to treat depression, but they belong to different classes of medications. Mirtazapine is an atypical antidepressant, specifically a tetracyclic antidepressant, while fluoxetine is a selective serotonin reuptake inhibitor (SSRI). Mirtazapine is taken once daily, usually at night, and is available as an oral tablet and an orally disintegrating tablet. In contrast, fluoxetine can be taken once or twice daily in its immediate-release form or once weekly in its delayed-release form. Mirtazapine is more likely to cause sleepiness and weight gain, whereas fluoxetine is less likely to cause these side effects but may lead to headaches and difficulty sleeping. Additionally, fluoxetine is approved for a wider range of conditions, including obsessive-compulsive disorder (OCD), bulimia, panic disorder, and depression from bipolar 1 disorder, while mirtazapine is only approved for major depressive disorder (MDD). Both medications can cause withdrawal symptoms if stopped abruptly and have a risk of serotonin syndrome, especially when taken with other medications that affect serotonin levels.
