Can I start with 7.5 mg of mirtazapine (Remeron)?

Starting Mirtazapine at 7.5 mg

Yes, you can start with 7.5 mg of mirtazapine, but this is actually below the recommended starting dose and may paradoxically cause more sedation rather than less. The standard recommendation is to begin at 15 mg once daily at bedtime 1, 2.

Why 7.5 mg Is Not Ideal

• Lower doses (below 15 mg) are associated with increased sedation rather than decreased side effects, which is counterintuitive but well-documented 3
• The sedation at subtherapeutic doses is related to mirtazapine's antihistamine (H1 receptor) effects being more prominent at lower doses, while the noradrenergic activation that counteracts sedation becomes more prominent at therapeutic doses 1
• Starting at 15 mg from the beginning of treatment results in substantially fewer patients reporting sedation compared to starting at lower doses 3

Recommended Starting Approach

• Begin with 15 mg once daily at bedtime as the standard starting dose 1, 2
• After 4 days at 15 mg, increase to 30 mg/day for 10 days if tolerated 2
• The effective dosage range is 15-45 mg/day, with most patients responding to 30 mg/day 1
• If insufficient improvement occurs at 30 mg/day, the dose may be increased to 45 mg/day 2

Clinical Considerations

• Mirtazapine has an elimination half-life of 20-40 hours, making once-daily bedtime dosing appropriate 1, 3
• The drug shows clinical antidepressant effects in 2-4 weeks, though sleep disturbances and anxiety symptoms may improve within the first week 1
• Peak plasma concentrations occur within 2.2-3.1 hours after oral administration 2

Common Pitfalls to Avoid

• Do not start at 7.5 mg thinking it will reduce side effects—this approach actually increases sedation 3
• Avoid gradual titration from very low doses; the evidence supports starting at the therapeutic dose of 15 mg 1, 2
• Monitor for increased appetite and weight gain, which are more common than with placebo (11% vs 2% for weight gain) 2

Safety Profile

• Mirtazapine has minimal cardiovascular and anticholinergic effects 1
• It lacks serotonergic side effects such as gastrointestinal symptoms, insomnia, and sexual dysfunction 1
• The drug is relatively safe in overdose, with cases up to 975 mg causing only significant sedation without cardiovascular or respiratory effects 1
• Agranulocytosis is rare (approximately 1 in 1,000) but is the most serious potential side effect 4