From the Guidelines
Mirtazapine is associated with several common side effects, including somnolence, constipation, diarrhea, dizziness, headache, insomnia, nausea, and sexual side effects, as reported in a clinical practice guideline from the American College of Physicians 1. The most commonly reported adverse events in patients taking mirtazapine include:
- Constipation
- Diarrhea
- Dizziness
- Headache
- Insomnia
- Nausea
- Sexual side effects
- Somnolence Nausea and vomiting were the most common reasons for discontinuation in efficacy studies, highlighting the need for careful consideration and monitoring when prescribing mirtazapine 1. It is essential to note that while mirtazapine has a faster onset of action compared to some other antidepressants, such as fluoxetine, paroxetine, or sertraline, a significant proportion of patients may not achieve a treatment response or remission within 6 to 12 weeks of treatment 1. In terms of minimizing side effects, starting with a lower dose and gradually increasing it can help reduce the severity of these effects, although the evidence base for this approach is limited 1. Overall, the benefits and risks of mirtazapine should be carefully weighed, and patients should be closely monitored for potential side effects, particularly during the initial treatment phase 1.
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 include serious side effects such as low white blood cell count, serotonin syndrome, and severe skin reactions, as well as common side effects like sleepiness, increased appetite, and weight gain 2.
- Serious side effects may also include eye problems, heart rhythm problems, mania or hypomania, seizures, and low sodium levels in the blood.
- Common side effects may also include dizziness. It is essential to monitor for these side effects and report any concerns to a healthcare provider 2.
From the Research
Side Effects of Mirtazapine
The side effects of mirtazapine have been studied in various clinical trials. Some of the known side effects include:
- Somnolence (increased risk) 3
- Weight gain (increased risk) 3
- Dry mouth (increased risk) 3
- Dizziness (increased risk) 3
- Increased appetite (increased risk) 3
- Headaches (decreased risk) 3
Suicidality Risk
The risk of suicidality with mirtazapine has been evaluated in several studies.
- One study found that mirtazapine might be associated with a lower risk of suicidality compared to placebo 4
- Another study reported two cases of patients who overdosed on mirtazapine and recovered without complications, suggesting that mirtazapine may be safe in overdose 5
- However, a systematic review with meta-analysis and trial sequential analysis found insufficient information to determine the effects of mirtazapine on the risks of suicides or suicide attempts 3
Long-Term Effects
The long-term effects of mirtazapine are not well understood, as most studies have only evaluated its effects over a short period (up to 12 weeks) 3
- One study evaluated the effect of sertraline with mirtazapine on depressive symptoms and inflammatory markers over an 8-week period, and found that the combination was effective and well-tolerated 6