What is the recommended dose and duration of mirtazapine (Remeron) for treating insomnia?

Mirtazapine Dosing for Insomnia Treatment

For insomnia treatment, mirtazapine should be started at a low dose of 7.5-15 mg once daily, administered orally in the evening prior to sleep, with treatment duration of 4-8 weeks based on recent clinical evidence. 1, 2, 3

Recommended Dosing

• The FDA-approved starting dose for mirtazapine is 15 mg once daily, preferably administered in the evening prior to sleep 1
• For insomnia specifically, lower doses (7.5-15 mg) are typically more effective than higher doses, as the sedating effects are more pronounced at lower doses 4, 2
• Dose adjustments should not be made in intervals of less than 1-2 weeks to allow sufficient time for evaluation of response 1

Evidence for Efficacy in Insomnia

• A 2025 randomized, double-blind, placebo-controlled trial demonstrated that low-dose mirtazapine (7.5-15 mg/day) provided a statistically significant and clinically relevant reduction in insomnia severity at 6 weeks compared to placebo 2
• Another 2025 randomized controlled trial in older adults showed that mirtazapine 7.5 mg significantly reduced insomnia symptoms after 28 days of treatment compared to placebo 3
• Mirtazapine's sedative properties are attributed to its potent histamine H1 receptor antagonism at low doses, as well as its 5-HT2A and 5-HT2C receptor blockade 4, 5

Duration of Treatment

• Clinical evidence supports short-term use (4-8 weeks) for insomnia treatment 2, 3
• The 2025 MIRAGE study demonstrated efficacy with a 28-day treatment course 3
• The 2025 DREAMING study showed benefits at 6 weeks, but noted that differences were not maintained at later time points (12,20, and 52 weeks) 2

Important Clinical Considerations

• Mirtazapine is not FDA-approved specifically for insomnia treatment and is considered an off-label use 4, 2
• The American Academy of Sleep Medicine does not include mirtazapine in their recommended medications for insomnia treatment 6
• For insomnia treatment, the American Academy of Sleep Medicine recommends:
  • CBT-I as first-line treatment 7
  • For pharmacological options: eszopiclone, zolpidem, and temazepam for both sleep onset and maintenance insomnia 6
  • For sleep maintenance insomnia specifically: doxepin (3-6 mg) and suvorexant 6, 8

Side Effects and Monitoring

• Common side effects of mirtazapine when used for insomnia include:
  • Somnolence (which may be beneficial for insomnia but problematic for daytime functioning) 5
  • Increased appetite and weight gain 5
• In the MIRAGE study, 6 participants in the mirtazapine group discontinued treatment due to adverse events compared to 1 in the placebo group 3
• When discontinuing mirtazapine, gradually reduce the dosage rather than stopping abruptly to minimize withdrawal symptoms 1

Cautions

• Screen for bipolar disorder prior to initiating mirtazapine treatment 1
• Be aware of potential drug interactions, particularly with strong CYP3A inducers or inhibitors, which may require dosage adjustments 1
• Consider that the American Academy of Sleep Medicine specifically recommends against using trazodone (another antidepressant) for insomnia treatment, suggesting caution with this class of medications 7, 9