From the Guidelines
The starting dose of mirtazapine should be 15 mg once daily. This recommendation is based on the most recent and highest quality study available, which suggests that mirtazapine can be initiated at a dose of 15 mg once daily, with dose titration according to response to treatment and tolerability to a maximum of 45 mg once daily 1.
Key Considerations
- The dose can be gradually increased every 1-2 weeks as needed and tolerated.
- Most patients respond to doses between 15-30 mg daily.
- Higher doses tend to be less sedating due to mirtazapine's unique pharmacology.
- It's essential to take mirtazapine consistently at the same time each evening to maintain therapeutic blood levels and maximize the benefit of its sedating properties for sleep.
Potential Side Effects
- Common side effects of mirtazapine include sleep disorders, constipation or diarrhea, anxiety, increased appetite and weight gain, nausea, headache, and fatigue 1.
- Initial side effects like drowsiness and increased appetite often improve after the first few weeks of treatment.
- Therapeutic effects for depression may take 2-4 weeks to become fully apparent.
From the FDA Drug Label
- 1 Recommended Dosage The recommended starting dose of mirtazapine tablets is 15 mg once daily, administered orally, preferably in the evening prior to sleep. The starting dose of mirtazapine is 15 mg once daily, administered orally, preferably in the evening prior to sleep 2.
- The dose can be increased up to a maximum of 45 mg per day if patients do not have an adequate response to the initial dose.
- Dose changes should not be made in intervals of less than 1 to 2 weeks to allow sufficient time for evaluation of response to a given dose.
From the Research
Starting Dose of Mirtazapine
- The starting dose of mirtazapine is typically in the range of 15-45 mg/day 3
- This dose range has been shown to lead to rapid and sustained improvements in depressive symptoms in patients with major depression, including the elderly 3
- Mirtazapine is generally well tolerated in patients with depression, with common adverse effects including dry mouth, sedation, and increases in appetite and body weight 4
Efficacy and Safety
- Mirtazapine has been established as an effective antidepressant in several placebo-controlled trials, with efficacy comparable to other antidepressants such as amitriptyline, clomipramine, doxepin, fluoxetine, paroxetine, citalopram, and venlafaxine 4, 5, 6
- Mirtazapine has also been shown to be effective in patients suffering from depression comorbid with anxiety symptoms and sleep disturbance 4
- The most frequently reported adverse events with mirtazapine are transient sedation and weight gain 5
Adverse Events
- A systematic review with meta-analysis and trial sequential analysis found that mirtazapine increases the risks of somnolence, weight gain, dry mouth, dizziness, and increased appetite, but decreases the risk of headaches 7
- However, the certainty of the evidence was very low, and there is a lack of evidence on the effects of mirtazapine on suicides and serious adverse events 7