Mirtazapine

Pronunciation: mer-TAZ-a-peen.

Generic name
mirtazapine
Drug class
Atypical (tetracyclic) antidepressant
Form
Tablet (film-coated or orally disintegrating), 15 mg, 30 mg, or 45 mg; oral solution also available in some markets
Route
Oral
Legal status
Prescription-only

Availability and supply rules vary by country

Trade names by country: United States · United Kingdom · Canada · Australia · New Zealand

Australia: Avanza (plus generics, e.g. Mirtazapine Sandoz) (5) · Full directory

What mirtazapine is and how it works

Mirtazapine is a prescription-only antidepressant used to treat major depressive disorder in adults. It works on a different set of brain chemical pathways from SSRIs, and commonly causes sleepiness and increased appetite, which is why it is sometimes chosen when depression comes with poor sleep or poor appetite. (1)

Take mirtazapine exactly as your prescriber directs, usually once daily in the evening. Dosing is individually adjusted -- your prescriber will choose a starting dose and may adjust it over time based on how you respond.

Mechanism of action: how mirtazapine works

Mirtazapine is a tetracyclic antidepressant of the piperazino-azepine group. It antagonises central presynaptic alpha2-adrenergic autoreceptors and heteroreceptors, which is thought to enhance central noradrenergic and serotonergic neurotransmission; it also has antihistaminergic activity, which contributes to its sedating and appetite-stimulating effects. (1)

What mirtazapine is used for

Major depressive disorder

Used to treat major depressive disorder (clinical depression) in adults. (1)

Before taking mirtazapine

Do not take / not appropriate for

  • Do not take mirtazapine if you are currently taking, or have taken within the last 14 days, a monoamine oxidase inhibitor (MAOI) -- this combination can cause a dangerous reaction. (all countries) (1)
  • Do not take mirtazapine if you have had a serious allergic reaction to it or any of its ingredients. (all countries) (1)

Tell your clinician about

  • Any personal or family history of bipolar disorder, since antidepressants can occasionally trigger mania or hypomania.
  • Any history of low white blood cell counts or bone marrow problems.
  • Any liver or kidney problems, which can change how mirtazapine is cleared from the body.
  • Any eye problems, particularly narrow-angle glaucoma.
  • All other medicines you take, especially other antidepressants, MAOIs, triptans, tramadol, or other serotonergic medicines.
  • Pregnancy, plans for pregnancy, or breastfeeding.
  • If you are 65 or older, since clearance and side-effect risk can differ with age.
(1)

How to take mirtazapine

  • Take once daily, usually in the evening before sleep, because it commonly causes drowsiness.
  • Swallow tablets whole, or let orally disintegrating tablets dissolve on the tongue as directed.
  • It may take several weeks of treatment for the full antidepressant effect to be felt.
  • Any change to your dose, including stopping treatment, should be planned with your prescriber rather than done on your own.
(1)

Procedures and treatment changes

Tell the treating team before surgery, procedures, or any medicine change. Do not alter treatment without the responsible clinician. (1) (2) (3) (4) (5) (6)

Missed dose

If you miss a dose, take it as soon as you remember unless it is close to the time of your next dose, in which case skip the missed dose. Do not take two doses together to make up for a missed one. Contact your prescriber if you are unsure.

Overdose

Seek urgent medical attention if you think too much mirtazapine has been taken, especially with symptoms such as marked drowsiness, disorientation, or a fast heartbeat. (1)

Side effects

Side effects and their urgency vary; report severe, persistent, or concerning symptoms.

Drowsiness/sleepiness (sedation) is very common, reported in over half of patients in trials.

What to notice: Drowsiness/sleepiness (sedation) is very common, reported in over half of patients in trials.

What to do: Discuss persistent or troublesome symptoms with the treating clinician or pharmacist. (1)

Increased appetite and weight gain.

What to notice: Increased appetite and weight gain.

What to do: Discuss persistent or troublesome symptoms with the treating clinician or pharmacist. (1)

Dizziness.

What to notice: Dizziness.

What to do: Discuss persistent or troublesome symptoms with the treating clinician or pharmacist. (1)

Increases in cholesterol levels have been observed in some patients.

What to notice: Increases in cholesterol levels have been observed in some patients.

What to do: Discuss persistent or troublesome symptoms with the treating clinician or pharmacist. (1)

Serious warnings

Signs of infection with a low white blood cell count (possible agranulocytosis/severe neutropenia) — boxed_warning

Symptoms: Fever, sore throat, mouth sores (stomatitis), or other signs of infection.

Action: Tell your prescriber urgently -- this is rare but serious, and blood tests will be needed. Your prescriber will decide whether treatment needs to be paused or changed. (1) (2)

Worsening depression or emergence of suicidal thoughts or behaviors — boxed_warning

Symptoms: New or worsening depression, agitation, unusual changes in behavior, or thoughts of self-harm -- especially early in treatment or after a dose change.

Action: Contact your prescriber urgently, or seek emergency help if there is immediate risk. Anyone taking this medicine should be closely watched for these changes, especially children, adolescents, and young adults. (1)

Signs of serotonin syndrome (especially with other serotonergic medicines) — emergency

Symptoms: Agitation, confusion, a fast heartbeat, high blood pressure, muscle twitching or stiffness, sweating, tremor, diarrhoea, or fever.

Action: Seek emergency medical help immediately. A clinician will assess and decide on treatment. (1)

Signs of mania or hypomania — high caution

Symptoms: Unusually elevated mood, racing thoughts, decreased need for sleep, or impulsive behavior.

Action: Tell your prescriber promptly; this can occasionally be triggered by antidepressants, particularly in people with an underlying bipolar tendency. (1)

Eye pain, vision changes, or redness (possible angle-closure glaucoma) — emergency

Symptoms: Sudden eye pain, blurred vision, halos around lights, or redness in one or both eyes.

Action: Seek urgent medical or eye-care attention -- this can be a sight-threatening emergency in susceptible individuals. (1)

Interactions

  • MAOIs are contraindicated -- combining them with mirtazapine, or starting mirtazapine within 14 days of stopping an MAOI, can cause a dangerous reaction. (1)
  • Other serotonergic medicines (SSRIs, SNRIs, triptans, tricyclic antidepressants, lithium, tramadol, buspirone, St John's Wort) can increase the risk of serotonin syndrome. (1)
  • Strong CYP3A inhibitors (such as ketoconazole or clarithromycin) or cimetidine can raise mirtazapine levels; your prescriber may choose a lower dose. (1)
  • Strong CYP3A inducers (such as phenytoin, carbamazepine, or rifampin) can lower mirtazapine levels; your prescriber may choose a higher dose. (1)
  • Alcohol and other sedating medicines can add to mirtazapine's drowsiness and impair alertness and coordination. (1)
  • Warfarin: your prescriber may want to monitor your blood-clotting tests (INR) more closely. (1)
  • Other medicines that can affect heart rhythm (QT-prolonging medicines) may increase the risk of an abnormal heart rhythm when combined. (4)

Pregnancy, breastfeeding, kidney/liver function, age

Pregnancy

There is no reliable evidence that mirtazapine causes birth defects, but untreated depression during pregnancy also carries risks. A pregnancy exposure registry exists to collect more information -- discuss the benefits and risks with your prescriber. (1) (2) (3) (4) (5) (6)

Breastfeeding

Mirtazapine passes into breast milk at low levels, and most reports have not shown adverse effects in breastfed infants. Discuss with your prescriber. (1) (2) (3) (4) (5) (6)

Children

Not approved for use in children; the boxed warning about suicidal thoughts and behaviors particularly concerns children, adolescents, and young adults. (1) (2) (3) (4) (5) (6)

Elderly

Use with caution in people 65 and older -- clearance is reduced, and there is a higher risk of low sodium levels (hyponatraemia) and excessive sedation. (1) (2) (3) (4) (5) (6)

Hepatic_impairment

Clearance is reduced by roughly a third to a half; your prescriber may choose a lower dose with moderate-to-severe liver impairment. (1) (2) (3) (4) (5) (6)

Renal_impairment

Clearance is reduced with kidney impairment; your prescriber may choose a lower dose with moderate-to-severe kidney impairment. (1) (2) (3) (4) (5) (6)

Monitoring

Before starting

  • Screening for personal/family history of bipolar disorder
  • Baseline weight and, where relevant, cholesterol
  • Review of other medicines for MAOI or serotonergic interactions

During treatment

  • Watching for worsening mood or suicidal thoughts, especially early in treatment and after dose changes.
  • Weight and appetite changes.
  • Any signs of infection (fever, sore throat, mouth sores), which need prompt blood-count checks.
  • Sodium levels in older adults, who have a higher risk of hyponatraemia.
(1)

Storage

Store at 20-25°C (68-77°F); brief excursions between 15-30°C (59-86°F) are permitted. Protect from light and moisture.

Study the drug class: SNRIs and other antidepressants

Professional information

Clinician-facing context only, sourced from the current US FDA prescribing information; verify against the current full label before prescribing.

United States

Indication: Major depressive disorder in adults

Dose summary: Starting dose 15 mg once daily, usually in the evening; effective range 15-45 mg daily; dose adjustments at intervals of at least 1-2 weeks. Gradual dose reduction is recommended when discontinuing, to reduce discontinuation-symptom risk.

Renal context: Clearance reduced roughly 30-50% with hepatic or renal impairment; dose reduction may be needed with moderate-to-severe impairment. (1)

Mechanism of action

Hepatic guidance

Clearance reduced roughly 30-50% in hepatic impairment; monitor and adjust dose accordingly.

Overdose note

Manage overdose with supportive care, including monitoring of cardiac and mental status; no specific antidote is described in the source reviewed. Fatalities in overdose are uncommon when mirtazapine is taken alone. (1)

Frequently asked questions

Is mirtazapine available in the US, UK, Europe, Canada, Australia, and New Zealand?

Yes, it is approved and widely available (mostly as generic mirtazapine, originally Remeron/Avanza) in all of these regions. (1) (2) (3) (4) (5) (6)

Why does mirtazapine make me sleepy and hungry?

Sedation and increased appetite are very common, expected effects of mirtazapine, related to how it acts on histamine receptors. This is one reason it is sometimes chosen for depression that comes with poor sleep or poor appetite. It is usually taken in the evening for this reason. (1)

Can I stop taking mirtazapine on my own if I feel better?

No. Any change to your dose or stopping treatment should be planned with your prescriber, who will usually recommend reducing the dose gradually, because ending mirtazapine abruptly can cause discontinuation symptoms such as dizziness, sensory disturbances, agitation, and nausea. (1)

What is the mechanism of action of mirtazapine?

Mirtazapine is a tetracyclic antidepressant of the piperazino-azepine group. It antagonises central presynaptic alpha2-adrenergic autoreceptors and heteroreceptors, which is thought to enhance central noradrenergic and serotonergic neurotransmission; it also has antihistaminergic activity, which contributes to its sedating and appetite-stimulating effects. (1)

What is the generic name of Mirtazapine?

The generic name is mirtazapine. (1)

What class of drug is mirtazapine?

Mirtazapine is classed as: Atypical (tetracyclic) antidepressant. (1)

References

  1. MIRTAZAPINE tablets, for oral use -- full prescribing informationU.S. Food and Drug Administration / DailyMed (NIH), full prescribing information · United States · accessed 2026-07-29 · source 1
  2. Mirtazapine 15mg/30mg/45mg Tablets -- Summary of Product Characteristics (multiple UK-licensed generic manufacturers)electronic medicines compendium (emc), United Kingdom · United Kingdom · accessed 2026-07-29 · source 2
  3. Mirtazapine -- list of nationally authorised medicinal products (PSUSA/00002068)European Medicines Agency (EMA) -- Periodic Safety Update Report Single Assessment (PSUSA) procedure · European Union · accessed 2026-07-29 · source 3
  4. REMERON (mirtazapine) Product MonographHealth Canada product monograph, Organon Canada Inc. · Canada · accessed 2026-07-29 · source 4
  5. AVANZA (mirtazapine) 30mg film-coated tablets -- ARTG registrationTherapeutic Goods Administration (TGA), Australia · Australia · accessed 2026-07-29 · source 5
  6. AVANZA (mirtazapine) New Zealand Data SheetMedsafe (New Zealand regulator) · New Zealand · accessed 2026-07-29 · source 6

Brand names by country

Single-ingredient mirtazapine names are shown separately by country. Product availability, strengths, and supply rules can change; combination products are not included here.

Priority countries

United States

  • REMERONSOLTAB15 mg, 30 mg, 45 mg · organon llc
  • REMERON15 mg, 30 mg · organon llc

United Kingdom

  • Mirtazapine (generic, multiple manufacturers) (2)MHRA licensed emc smpc confirmed · 15 mg, 30 mg, 45 mg · multiple licensed manufacturers

Canada

  • REMERON RD
  • REMERON
  • TEVA-MIRTAZAPINE OD
  • AURO-MIRTAZAPINE OD

Australia

  • Avanza (plus generics, e.g. Mirtazapine Sandoz) (5)TGA ARTG registered 2001-02-20 confirmed · 15 mg, 30 mg, 45 mg · Organon Pharma Pty Ltd

New Zealand

  • Avanza (plus generics, e.g. Mirtazapine Noumed) (6)Medsafe approved confirmed · 15 mg, 30 mg, 45 mg · multiple registered suppliers
View brands in additional countries.

European Union

Mirtazapine (nationally authorised generics, e.g. Sandoz) (3)

This page provides general reference information about mirtazapine and is not a substitute for advice from the prescriber managing your treatment. All dosing and treatment decisions should be made with your prescriber.

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