From the Guidelines
Mirtazapine is associated with several common side effects, including sedation, weight gain, dry mouth, constipation, and dizziness, as reported in various studies, including a clinical practice guideline from the American College of Physicians 1. When considering the side effects of Mirtazapine, it's essential to weigh the benefits against the potential risks, particularly in terms of morbidity, mortality, and quality of life.
- Common side effects of Mirtazapine include:
- Sedation or drowsiness, especially at lower doses
- Weight gain due to increased appetite and carbohydrate cravings
- Dry mouth
- Constipation
- Dizziness
- Less common but possible side effects include:
- Vivid dreams
- Confusion
- Edema (swelling)
- Rarely, serious conditions like agranulocytosis (decreased white blood cell count) or serotonin syndrome when combined with other serotonergic medications The sedative effects of Mirtazapine are typically more pronounced at lower doses because it primarily affects histamine receptors at these levels, while at higher doses, its noradrenergic effects become more dominant, as suggested by the clinical practice guideline 1. Most side effects tend to improve after several weeks of treatment as the body adjusts to the medication, and taking Mirtazapine at bedtime can help manage the sedation, making it useful for patients with insomnia alongside depression. The most recent and highest quality study, a clinical practice guideline from the American College of Physicians 1, provides the best evidence for the side effects of Mirtazapine, and its findings should be prioritized when making treatment decisions.
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 most common side effects of mirtazapine tablets include: • sleepiness • increased appetite • weight gain • dizziness
The side effects of Mirtazapine (Remeron) include:
- Serious side effects: Low white blood cell count, serotonin syndrome, eye problems, heart rhythm problems, severe skin reaction, mania or hypomania, seizures, increased fat levels, low sodium levels, changes in liver function tests, and discontinuation syndrome.
- Common side effects: sleepiness, increased appetite, weight gain, and dizziness 2
From the Research
Side Effects of Mirtazapine (Remeron)
The side effects of Mirtazapine (Remeron) are well-documented in various studies 3, 4, 5, 6, 7. Some of the most common side effects include:
- Somnolence (drowsiness) 3, 4, 5, 6
- Increased appetite 3, 4, 5, 7
- Weight gain 3, 4, 5, 7
- Dizziness 3
- Dry mouth 4, 5, 7
- Sedation 4, 5, 6
- Excessive sedation 4
Less Common Side Effects
Less common side effects of Mirtazapine include:
- Agranulocytosis (a rare but serious blood disorder) 4, 6
- Neutropenia (a decrease in white blood cells) 4
- Elevated liver enzymes 4
- Elevated cholesterol levels 4
- Anticholinergic events (such as tremor and dyspepsia) 7
Comparison to Other Antidepressants
Mirtazapine has been compared to other antidepressants in terms of its side effect profile. It has been found to have a similar tolerability profile to selective serotonin reuptake inhibitors (SSRIs) 5, 7, but with a lower incidence of anticholinergic events and other side effects compared to tricyclic antidepressants 4, 7. Additionally, Mirtazapine has been found to have a lower incidence of sexual side effects compared to SSRIs 5, 6.