What are the disadvantages of Mirtazapine?

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From the Guidelines

Mirtazapine has several disadvantages, including somnolence, increased appetite, and weight gain.

Common Adverse Events

  • The most commonly reported adverse events associated with mirtazapine are constipation, diarrhea, dizziness, headache, insomnia, nausea, sexual side effects, and somnolence 1.

Discontinuation Due to Adverse Events

  • Nausea and vomiting were the most common reasons for discontinuation in efficacy studies 1.

Comparison with Other Antidepressants

  • Mirtazapine had a faster onset of action than fluoxetine, paroxetine, or sertraline, but the overall efficacy and effectiveness of mirtazapine were similar to those of other second-generation antidepressants 1.

Specific Adverse Events

  • Mirtazapine may be associated with an increased risk of somnolence and weight gain 1. It is essential to carefully evaluate the potential benefits and risks of mirtazapine and monitor patients for adverse events, particularly during the initial treatment period.

From the FDA Drug Label

Mirtazapine tablets may cause serious side effects, including: • Low white blood cell count. • Serotonin syndrome • Eye problems (angle-closure glaucoma). • Heart rhythm problems. • Severe skin reaction • Increased appetite and weight gain. • Sleepiness. • Mania or hypomania (manic episodes) in people who have a history of bipolar disorder. • Seizures (convulsions). • Increased fat levels (cholesterol and triglycerides) in your blood • Low sodium levels in your blood (hyponatremia). • Changes in liver function tests. • Discontinuation syndrome.

The disadvantages of Mirtazapine include:

  • Serious side effects: such as low white blood cell count, serotonin syndrome, and severe skin reactions
  • Common side effects: such as sleepiness, increased appetite, and weight gain
  • Increased risk of: mania or hypomania in people with a history of bipolar disorder, seizures, and changes in liver function tests
  • Discontinuation syndrome: which can occur when the medication is stopped abruptly
  • Interactions with other medications: that can increase the risk of serious side effects, such as serotonin syndrome and heart rhythm problems 2

From the Research

Disadvantages of Mirtazapine

The disadvantages of mirtazapine include:

  • Dry mouth, sedation, and increases in appetite and body weight are the most common adverse effects 3
  • Drowsiness, excessive sedation, dry mouth, increased appetite, and bodyweight gain occurred significantly more frequently with mirtazapine in placebo-controlled trials 4, 5
  • Mirtazapine is associated with potentially serious changes in haematological parameters, such as agranulocytosis and neutropenia, although these are rare 5
  • Increased sedation associated with the drug is related to subtherapeutic dosages 6
  • Mirtazapine may cause somnolence, increased appetite, weight gain, and dizziness 7
  • The drug may have a low seizure-inducing potential, but this is still a potential risk 4, 5
  • Mirtazapine may cause elevated cholesterol levels, with a mean increase of 3 to 4% 5
  • The drug may cause granulocytopenia and elevated alanine aminotransferase levels, although most cases are mild in severity and return to normal values with continued administration of mirtazapine 5

References

Guideline

Guideline Directed Topic Overview

Dr.Oracle Medical Advisory Board & Editors, 2025

Research

Safety of mirtazapine: a review.

International clinical psychopharmacology, 1995

Research

Mirtazapine, an antidepressant.

American journal of health-system pharmacy : AJHP : official journal of the American Society of Health-System Pharmacists, 1998

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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