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mirtazapine

Adjunctive therapy

Brand: Remeron

Published 2025-09-28 · Last reviewed 2025-10-05 · 4 references

Content sourced from FDA labeling (DailyMed) and peer-reviewed literature.

Print sheet Review evidence

At a glance

Class: Adjunctive therapy·Typical dose: Typical adult initiation: 15 mg at bedtime; increase to 30 mg after 1–2 weeks based on response; usual maintenance 15–45 mg nightly.·Half-life: Single-dose mean 30 h; Single-dose range 20–40 h; Steady-state mean 37 h·LAI available: No

Class: Adjunctive therapy
Typical dose: Typical adult initiation: 15 mg at bedtime; increase to 30 mg after 1–2 weeks based on response; usual maintenance 15–45 mg nightly.
Half-life: Single-dose mean 30 h; Single-dose range 20–40 h; Steady-state mean 37 h
LAI available: No

Quick answers

What is mirtazapine?: Mirtazapine (Remeron) is a noradrenergic and specific serotonergic antidepressant (NaSSA) approved for major depressive disorder and frequently chosen for patients needing sedation, appetite stimulation, or an augmentation option with low sexual side-effect burden.
What is Remeron?: Remeron is a brand name for mirtazapine.
What is Remeron (mirtazapine) used for?: Label indications include: Major depressive disorder.
What drug class is Remeron (mirtazapine)?: NaSSA Antidepressant.
What is the mechanism of action of Remeron (mirtazapine)?: Central presynaptic alpha-2 antagonist; enhances noradrenergic and serotonergic transmission (NaSSA).
What strengths does Remeron (mirtazapine) come in?: Tablets and orally disintegrating tablets: 7.5–45 mg.

General information

Mirtazapine (Remeron) is a noradrenergic and specific serotonergic antidepressant (NaSSA) approved for major depressive disorder and frequently chosen for patients needing sedation, appetite stimulation, or an augmentation option with low sexual side-effect burden.

Despite advantages for insomnia or cachexia, weight gain and metabolic monitoring are central considerations when selecting mirtazapine as monotherapy or adjunct therapy.

The compare tool can help contrast sedation, weight change, and activation strategies, and mirtazapine evidence summaries can support review when adjusting augmentation plans.

For bipolar-spectrum augmentation or insomnia management, follow-up can be coordinated with the bipolar disorder hub, and counselling materials from the mirtazapine print view can support monitoring expectations.

U.S. approvals

Major depressive disorder (1996)

Formulations & strengths

Tablets and orally disintegrating tablets: 7.5–45 mg.

Generic availability

Generics widely available.

Sedation and weight gain make metabolic monitoring standard; rare agranulocytosis makes infection-symptom counseling important.

View labelExact

Mechanism of action

Refer to the Glossary entry on Neurotransmitters for background on receptor systems involved in serious mental illness.

Antagonizes central α2 autoreceptors and heteroreceptors, increasing norepinephrine and serotonin release, and blocks 5-HT2 and 5-HT3 receptors while enhancing 5-HT1A transmission.

Potent H1 antagonism explains strong sedative and appetite-stimulating effects.

α2 antagonist; 5-HT2/5-HT3 antagonist; potent H1 antagonist.

Metabolism & pharmacokinetics

Peak ~2 h; half-life 20–40 h.
Metabolized via CYP1A2, CYP2D6, CYP3A4 to inactive metabolites; eliminated renally and via feces.

Dosing & administration

Typical adult initiation: 15 mg at bedtime; increase to 30 mg after 1–2 weeks based on response; usual maintenance 15–45 mg nightly.
Lower doses (7.5–15 mg) can cause more prominent sedation; doses ≥30 mg often provide stronger antidepressant effects with relatively less sedation.
Older adults or patients with renal/hepatic impairment often start 7.5–15 mg nightly with cautious titration; doses may be limited to 30 mg/day in moderate impairment.
Tapering is typically gradual over weeks to avoid cholinergic rebound and discontinuation symptoms.

Monitoring & labs

Weight and appetite changes, plus fasting lipids and glucose at baseline and periodically, given weight gain and dyslipidemia risk.
Daytime sedation and falls risk, especially in older adults and when other sedatives are co-prescribed.
Infection symptoms (fever, sore throat) given rare neutropenia; prompt evaluation is appropriate when symptoms arise.
Mood elevation or agitation in bipolar-spectrum illness; coordinate prevention plans via the bipolar disorder hub.

Mirtazapine is often chosen for insomnia and poor appetite; metabolic monitoring and anticipatory counseling on weight gain are key to sustained adherence. Sedation precautions and infection symptom reporting are commonly revisited throughout treatment.

Adverse effects

FDA boxed warnings

Antidepressants increase suicidality risk in young adults; closer monitoring is common.

Common side effects (≥10%)

Somnolence: ≈50%; consistent bedtime dosing is common, and driving precautions are commonly discussed.
Increased appetite/weight gain: BMI, fasting lipids, and glucose are typically monitored at baseline and during therapy.
Dry mouth: Hydration and oral hygiene counseling is common.
Constipation: Fiber, hydration, and stool softeners are commonly discussed when necessary.
Dizziness/orthostasis: Slow positional changes are commonly recommended, especially in older adults.

Other notable effects

Hypertriglyceridemia and mild increases in cholesterol can occur—lipids are often checked periodically.
Rare agranulocytosis or neutropenia—education often includes reporting fever, sore throat, or infection symptoms promptly.

Interactions

Contraindicated with MAOIs; a 14-day washout is typically used to avoid hypertensive crisis or serotonin syndrome.
Additive sedation with alcohol, benzodiazepines, opioids, or other CNS depressants—driving and machinery precautions are commonly discussed.
CYP1A2/2D6/3A4 inhibitors (fluvoxamine, paroxetine, ketoconazole) increase levels; inducers (carbamazepine, phenytoin) lower exposure—dose adjustments are guided by clinical response.
Combined serotonergic agents (SSRIs, SNRIs, linezolid, triptans, tramadol) increase serotonin syndrome risk; combinations are often avoided or monitored closely.

Other useful information

Good option for depression with insomnia, poor appetite, or sexual dysfunction intolerance; lifestyle strategies to counter metabolic effects are often discussed.
Weight/BMI, blood pressure, and fasting lipids/glucose are typically monitored at baseline and periodically during therapy.
Education often covers agranulocytosis warning signs (fever, sore throat) and that these symptoms warrant prompt evaluation.
Pregnancy planning and breastfeeding are typically discussed; obstetrics coordination is common to weigh benefits versus potential risks.
In bipolar depression augmentation, monitoring for emergent mania/hypomania can be coordinated with the bipolar disorder hub.
Dosing time matters: bedtime dosing is typical for sedation; if daytime fatigue persists, dose, other sedatives, and sleep disorders are often reassessed.

References

Related hubs:SMI toolkit·Support resources