What to Expect When Starting Mirtazapine
Medical Disclaimer: This content is for informational purposes only and does not constitute medical advice. Always consult your healthcare provider before starting, stopping, or changing any medication. Using this site does not create a doctor-patient relationship.
Drug information changes as the FDA updates labeling, and we cannot guarantee it is complete or current. Verify critical details with your pharmacist or physician.
Emergencies: If you think you may have a medical emergency, call 911 immediately. For a suspected overdose, call Poison Control at 1-800-222-1222. Report side effects to the FDA MedWatch program at fda.gov/medwatch or 1-800-FDA-1088.
See our Terms of Use and Editorial Policy.
Introduction
Mirtazapine (Remeron) is a noradrenergic and specific serotonergic antidepressant (NaSSA) used to treat major depressive disorder and sometimes anxiety, insomnia, and appetite loss in medically ill patients. Unlike SSRIs, it works by blocking alpha-2 receptors and certain serotonin receptors. It is notably sedating — especially at lower doses — and causes significant appetite stimulation, making it particularly useful for depressed patients with insomnia and weight loss.
Week-by-week timeline
Starting at 15 mg at Bedtime
Mirtazapine is started at 15 mg taken at bedtime due to its pronounced sedating effect. Expect strong sedation and improved sleep quality almost immediately. Appetite and carbohydrate cravings increase notably. Drowsiness persists into the morning for some patients.
Adjusting to Side Effects
Sedation typically lessens as the body adjusts, though it remains for most patients. Appetite increase and weight gain continue. Antidepressant effect has not yet peaked — mood improvements may be subtle. Dry mouth and constipation are common.
Emerging Antidepressant Effect
Mood begins to lift noticeably around weeks 3-4. Sleep quality remains improved. Energy and motivation improve. If sedation is too disruptive, dose may be increased to 30 mg (paradoxically, higher doses are less sedating due to receptor changes).
Full Therapeutic Benefit
Full antidepressant effect is typically evident by 6-8 weeks. Weight gain of 1-4 kg is common by this point. Mood, sleep, and appetite are all substantially improved in most patients.
Long-Term Continuation
Continue mirtazapine for at least 6-12 months after remission to prevent relapse. Weight monitoring is important long-term. Do not stop abruptly — taper gradually when discontinuing.
When to call your doctor
Contact your healthcare provider if you experience:
- Thoughts of self-harm or suicidal thinking, especially in the first few weeks
- Signs of serotonin syndrome: agitation, high fever, rapid heart rate, muscle stiffness
- Severe allergic reaction: rash, difficulty breathing, facial swelling
- New or worsening anxiety or panic attacks
- Unusual bleeding or bruising
- Seizures
Tips for getting started
Take mirtazapine at bedtime — its sedating effects are a feature, not a bug. Do not drive or operate machinery until you know how it affects you the next morning. Be mindful of increased appetite and weight gain — planning healthy meals and light exercise can help manage this. Do not stop mirtazapine abruptly as discontinuation can cause nausea, insomnia, and dizziness. Continue taking it even once you feel better for the full recommended duration.
Frequently asked questions
More about Mirtazapine
References
- [Regulatory] FDA Prescribing Information for Remeron (mirtazapine) https://www.accessdata.fda.gov/drugsatfda_docs/label/2023/020415s022lbl.pdf Accessed 2026-03-01.
- [Regulatory] NIH MedlinePlus: Mirtazapine https://medlineplus.gov/druginfo/meds/a697009.html Accessed 2026-03-01.
- [Regulatory] NIMH Depression Overview and Treatments https://www.nimh.nih.gov/health/topics/depression Accessed 2026-03-01.
Written and fact-checked by PrescriptionDrugs.org Editorial Team
Last updated: