Mirtazapine
Meta-analyses found mirtazapine reduced depression more than placebo and acted faster than SSRIs in the first two weeks. Two small trials found low doses eased insomnia for about six weeks. Trials in cancer found no gain in appetite over placebo. Sleepiness affected 54% against 18% on placebo, and the label carries the antidepressant boxed warning on suicidal thoughts.
- Status
- Prescription drug in the US, FDA-approved for major depressive disorder in adults. It is not approved for insomnia, appetite or weight gain, nausea or anxiety, which are off-label uses.
- Also called
- Remeron, RemeronSolTab, mirtazapine orally disintegrating tablets, tetracyclic antidepressant, NaSSA
- Taken for
- depression, sleep, insomnia, appetite, weight gain, nausea, anxiety
Strong several reviews agree · Moderate one review or consistent trials · Limited one or a few small studies · Untested no study in people, listed with what it rests on
Shown to help3
- StrongShown to reduce depression more than placebo in adults, with a higher response rate than SSRIs at two weeks and at the end of acute treatment.
- ModerateShown to lower insomnia severity by about 6 points more than placebo at 6 weeks on low-dose mirtazapine, with no difference from placebo from 12 weeks.Very common
- ModerateShown to cut nausea and vomiting after surgery by about half against placebo across three trials, with far more sedation.
Reported risks18
- StrongShown to cause sleepiness in 54% against 18% on placebo in 6-week depression trials, leading 10.4% to stop against 2.2%.Very common
- StrongShown to cause increased appetite in 17% against 2% on placebo, and a weight gain of 7% or more in 7.5% against 0.Very common
- ModerateShown to cause dry mouth in 25% against 15% on placebo, constipation in 13% against 7% and dizziness in 7% against 3%.Very common
- ModerateShown to raise nonfasting cholesterol to 20% or more above the normal limit in 15% against 7% on placebo, and triglycerides to 500 mg/dL or more in 6% against 3%.Very common
- ModerateFDA states antidepressants raised suicidal thoughts and behaviors in pediatric and young adult patients in short-term trials, 14 more cases per 1,000 under age 18.Common
- ModerateShown to raise the liver enzyme ALT to three times the normal limit or more in 2.0% against 0.3% on placebo in short trials.Common
- LimitedOne trial found 7 deaths on mirtazapine against 1 on placebo by week 16 in people with dementia, a difference of marginal statistical significance.Common
- LimitedThe label reports symptoms of mania or hypomania in 0.2% of people treated with mirtazapine in controlled trials that mostly excluded bipolar disorder.Uncommon
- LimitedThe label reports agranulocytosis in 2 of 2,796 people in premarketing trials, and severe neutropenia in a third. All three recovered after stopping.Rare
- LimitedThe label reports 1 seizure among 2,796 people treated with mirtazapine in premarketing trials.Rare
- LimitedThe label reports QT interval lengthening rose with mirtazapine blood levels in a 54-person study, below a level considered clinically meaningful, with postmarketing reports of torsades de pointes.How often is not known
- LimitedThe label warns that mirtazapine can precipitate serotonin syndrome, with higher risk alongside other serotonergic drugs. It gives no rate.How often is not known
- LimitedThe label lists MAOIs as a contraindication because the combination increases the risk of serotonin syndrome. It gives no rate.How often is not known
- LimitedThe label states that benzodiazepines or alcohol taken with mirtazapine increase the impairment of thinking and motor skills beyond mirtazapine alone. It gives no rate.How often is not known
- LimitedThe label states that strong inducers of a liver enzyme lower mirtazapine blood levels, and that strong inhibitors and cimetidine may raise them.How often is not known
- LimitedThe label reports dizziness, abnormal dreams, electric shock sensations, agitation, anxiety, nausea and sweating after stopping mirtazapine, particularly abruptly. It gives no rate.How often is not known
- LimitedThe label reports severe skin reactions after mirtazapine, including drug reaction with eosinophilia and systemic symptoms, Stevens-Johnson syndrome and toxic epidermal necrolysis. It gives no rate.How often is not known
- LimitedMixed results: most studies found outcomes like those in unexposed pregnancies, findings on birth defects and miscarriage conflicted, and newborn adaptation symptoms followed late exposure.How often is not known
What people take it for, and what was found
Shown to help3
Depression in adults
Shown to reduce depression more than placebo in adults, with a higher response rate than SSRIs at two weeks and at the end of acute treatment.
The numbers and sources
- Effect
- In a network meta-analysis of 522 trials, every antidepressant studied had a higher response rate than placebo, with odds ratios from 1.37 to 2.13, and in head-to-head trials mirtazapine was among seven drugs with higher response rates than other antidepressants (odds ratios 1.19 to 1.96) [1]. In a Cochrane review, mirtazapine had a higher response rate than SSRIs at two weeks (OR 1.57, 95% CI 1.30 to 1.88) and at the end of acute treatment (OR 1.19, 95% CI 1.01 to 1.39), and than venlafaxine (OR 1.53, 95% CI 1.03 to 2.25). It did not differ from tricyclic antidepressants (OR 0.89, 95% CI 0.72 to 1.10), and dropouts did not differ from other antidepressants [2].
- Population
- 116,477 adults in 522 trials [1]; 4,974 participants in 29 trials, most followed for six weeks [2].
- Sources
- [1], [2]
- Caveats
- The network meta-analysis rated certainty moderate to very low, and its abstract does not give the mirtazapine figure against placebo. Most trials lasted 6 to 12 weeks.
Insomnia
Shown to lower insomnia severity by about 6 points more than placebo at 6 weeks on low-dose mirtazapine, with no difference from placebo from 12 weeks.
The numbers and sources
- How common
- Very common: more than 1 in 10 people.
- Effect
- In adults with insomnia disorder in general practice, low-dose mirtazapine lowered Insomnia Severity Index scores by 6.0 points more than placebo at 6 weeks (95% CI 3.0 to 9.0). Improvement and recovery rates were 52% and 56% against 14% on placebo. From 12 weeks onward scores did not differ from placebo [3]. In adults aged 65 and over, 28 days of mirtazapine 7.5 mg lowered scores by 6.5 points against 2.9 on placebo, and improved self-rated time awake in the night, total sleep time and sleep efficiency. Six people on mirtazapine and one on placebo stopped because of adverse events [4].
- Population
- 80 adults with insomnia disorder and trouble staying asleep [3]; 60 adults aged 65 and over with chronic insomnia [4].
- Sources
- [3], [4]
- Caveats
- Two small trials. Not an approved use. The authors of [3] concluded the results do not support use for several months.
Nausea and stomach symptoms
Shown to cut nausea and vomiting after surgery by about half against placebo across three trials, with far more sedation.
The numbers and sources
- Effect
- Mirtazapine given before surgery reduced postoperative nausea and vomiting against placebo (RR 0.44, 95% CI 0.32 to 0.62) and gave rates similar to ondansetron in one trial (RR 0.96, 95% CI 0.48 to 1.94). Sedation was more frequent (RR 22.47, 95% CI 5.61 to 89.93) [8]. In people with functional dyspepsia not helped by standard drugs, 8 weeks of mirtazapine improved dyspepsia symptom scores, including fullness after meals, early satiation, nausea and vomiting, and increased weight against a control group [9]. In depression trials, mirtazapine caused less nausea or vomiting than SSRIs [2].
- Population
- Three placebo-controlled trials in surgical patients [8]; 120 patients with functional dyspepsia [9]; 2,626 participants in 12 trials against SSRIs [2].
- Sources
- [8], [9], [2]
- Caveats
- Not an approved use. Evidence quality for the surgery analysis was rated moderate to low, and the dyspepsia trial was single-center. No trial in chemotherapy nausea or pregnancy nausea was sourced for this page.
Mixed results1
Anxiety
Mixed results: mirtazapine matched SSRIs and benzodiazepines for generalized anxiety in small trials, with no placebo comparison among the pooled results.
The numbers and sources
- Effect
- In a meta-analysis of 37 studies, mirtazapine did not differ from SSRIs in generalized anxiety disorder (SMD -0.14, 95% CI -0.38 to 0.09) or from benzodiazepines (SMD -0.03, 95% CI -0.83 to 0.77). In people with major depression, it reduced anxiety symptoms slightly more than SSRIs (SMD -0.16) [10]. Before surgery it reduced anxiety against placebo or ondansetron (SMD -1.4, 95% CI -2.56 to -0.23) [8].
- Population
- 330 participants in 5 comparisons with SSRIs and 233 in 4 with benzodiazepines in generalized anxiety disorder, and 1,732 in 10 comparisons in depression [10].
- Sources
- [10], [8]
- Caveats
- Not an approved use. Matching another drug is not the same as beating placebo, and heterogeneity was high in the benzodiazepine comparison (I² 85.9%).
Not shown to help4
Appetite and weight gain
Not shown to improve appetite scores more than placebo in two trials of people with cancer, though energy intake rose in one.
The numbers and sources
- Effect
- In people with incurable solid tumors and cancer-related loss of appetite and weight, appetite scores rose on mirtazapine 15 mg and on placebo, with no difference between them after 28 days [5]. In people with advanced lung cancer and anorexia, appetite scores did not differ from placebo at 4 or 8 weeks. Energy intake was 379.3 kcal higher on mirtazapine at 4 weeks, and fewer people had sarcopenia at 8 weeks (57.1% against 82.8%) [6]. In depression trials, increased appetite was reported as a side effect by 17% against 2% on placebo [7].
- Population
- 100 assessable patients with incurable solid tumors [5]; 86 patients with advanced non-small cell lung cancer [6]; 453 adults with depression on mirtazapine and 361 on placebo [7].
- Sources
- [5], [6], [7]
- Caveats
- Not an approved use. Both trials were in cancer. No placebo-controlled trial of mirtazapine for low appetite or low weight in other groups was located. See the weight gain block under risks.
Depression not helped by an SSRI or SNRI, as an add-on
One trial found adding mirtazapine to an SSRI or SNRI did not clearly lower depression scores against placebo at 12 weeks in primary care.
The numbers and sources
- Effect
- At 12 weeks, mean Beck depression scores were 18.0 on added mirtazapine and 19.7 on added placebo (adjusted difference -1.83, 95% CI -3.92 to 0.27). Adverse effects were more common on mirtazapine and were associated with stopping the trial drug [11].
- Population
- Adults in primary care with depression that had not responded to an SSRI or SNRI [11].
- Sources
- [11]
- Caveats
- One trial. The confidence interval includes both no effect and a small benefit.
Agitation in dementia
One trial found mirtazapine did not reduce agitation scores against placebo at 12 weeks in 204 people with dementia.
The numbers and sources
- Effect
- Mean agitation scores at 12 weeks did not differ between mirtazapine and placebo (adjusted mean difference -1.74, 95% CI -7.17 to 3.69). Adverse events occurred in 66% on mirtazapine and 64% on placebo. By week 16 there were 7 deaths on mirtazapine and 1 on placebo [12].
- Population
- 204 people with dementia and agitated behaviors [12].
- Sources
- [12]
- Caveats
- One trial. Not an approved use. See the block on deaths in this trial under risks.
Depression in dementia
One trial found mirtazapine did not lower depression scores against placebo at 13 or 39 weeks in people with dementia.
The numbers and sources
- Effect
- The fall in depression scores at 13 weeks did not differ between mirtazapine and placebo (difference 0.01, 95% CI -1.37 to 1.38), and the finding held to 39 weeks. Adverse reactions occurred in 41% on mirtazapine (44 of 108) and 26% on placebo (29 of 111) [13].
- Population
- People with dementia and depression randomized to mirtazapine (108), sertraline (107) or placebo (111) [13].
- Sources
- [13]
- Caveats
- One trial, in people with Alzheimer's disease receiving usual care.
Doses studied
The label gives a starting dose of 15 mg once a day, preferably in the evening before sleep, raised up to 45 mg a day. The label's 6-week US trials dosed people from 5 to 60 mg a day [7].
The insomnia trial in older adults used 7.5 mg for 28 days [4], and the general practice trial used a low dose, with follow-up beyond 12 weeks [3]. The cancer appetite trial used 15 mg at night for 28 days [5].
Risks
Reported risks17
Sleepiness
Shown to cause sleepiness in 54% against 18% on placebo in 6-week depression trials, leading 10.4% to stop against 2.2%.
The numbers and sources
- How common
- Very common: more than 1 in 10 people.
- Effect
- In US controlled trials, somnolence was reported by 54% on mirtazapine and 18% on placebo, and led to discontinuation in 10.4% against 2.2%. The label states it is unclear whether tolerance develops [7]. In a network meta-analysis of on-road driving trials in healthy subjects, mirtazapine 15 to 30 mg at bedtime produced significantly more lane weaving the next morning than placebo after a single dose [14]. Mirtazapine caused more somnolence than SSRIs in depression trials [2], and more sedation than placebo before surgery (RR 22.47, 95% CI 5.61 to 89.93) [8].
- Population
- 453 adults on mirtazapine and 361 on placebo [7]; 22 crossover trials of sleep-related medicines in healthy subjects [14]; 4,974 participants in 29 trials [2].
- Sources
- [7], [14], [2], [8]
- Caveats
- Confidence in the driving evidence was rated low to very low, and repeated dosing caused fewer residual effects than a single dose [14].
Increased appetite and weight gain
Shown to cause increased appetite in 17% against 2% on placebo, and a weight gain of 7% or more in 7.5% against 0.
The numbers and sources
- How common
- Very common: more than 1 in 10 people.
- Effect
- In US controlled trials, increased appetite was reported by 17% on mirtazapine and 2% on placebo, weight gain as an adverse reaction by 12% against 2%, and a gain of 7% or more of body weight by 7.5% against 0. In premarketing studies that included long-term open-label treatment, 8% stopped because of weight gain. In an 8-week pediatric trial, 49% gained at least 7% against 5.7% on placebo [7]. Mirtazapine was more likely than SSRIs to cause weight gain or increased appetite [2].
- Population
- 453 adults on mirtazapine and 361 on placebo in 6-week trials, and children in an 8-week trial [7]; 2,626 participants in 12 trials against SSRIs [2].
- Sources
- [7], [2]
- Caveats
- Six-week trials, so longer-term weight change is not measured here. Mirtazapine is not approved for children.
Dry mouth, constipation and dizziness
Shown to cause dry mouth in 25% against 15% on placebo, constipation in 13% against 7% and dizziness in 7% against 3%.
The numbers and sources
- How common
- Very common: more than 1 in 10 people.
- Effect
- In 6-week US trials: dry mouth 25% vs 15% on placebo, constipation 13% vs 7%, asthenia 8% vs 5%, dizziness 7% vs 3% and peripheral edema 2% vs 1% [7].
- Population
- 453 adults on mirtazapine and 361 on placebo [7].
- Sources
- [7]
- Caveats
- Six-week trials at 5 to 60 mg a day.
Raised cholesterol and triglycerides
Shown to raise nonfasting cholesterol to 20% or more above the normal limit in 15% against 7% on placebo, and triglycerides to 500 mg/dL or more in 6% against 3%.
The numbers and sources
- How common
- Very common: more than 1 in 10 people.
- Effect
- In US controlled studies, nonfasting cholesterol rose to at least 20% above the upper limit of normal in 15% on mirtazapine and 7% on placebo, and nonfasting triglycerides rose to 500 mg/dL or more in 6% against 3% [7].
- Population
- Adults in US controlled studies of mirtazapine [7].
- Sources
- [7]
- Caveats
- Nonfasting samples in short trials. No trial here measured heart attacks or strokes.
FDA boxed warning: suicidal thoughts and behaviors in young people
FDA states antidepressants raised suicidal thoughts and behaviors in pediatric and young adult patients in short-term trials, 14 more cases per 1,000 under age 18.
The numbers and sources
- How common
- Common: between 1 in 100 and 1 in 10 people.
- Effect
- The label carries the antidepressant boxed warning and states that mirtazapine is not approved for pediatric patients. In FDA's pooled analyses of placebo-controlled antidepressant trials in about 77,000 adults and 4,500 pediatric patients, the difference from placebo in patients with suicidal thoughts or behaviors per 1,000 treated was 14 more under age 18, 5 more at ages 18 to 24, 1 fewer at ages 25 to 64 and 6 fewer at 65 and older [7].
- Population
- Placebo-controlled trials of antidepressants pooled by FDA [7].
- Sources
- [7]
- Caveats
- The pooled analyses cover antidepressants as a group, not mirtazapine alone. The label reports differences from placebo, not absolute rates, so the band above is the excess under age 18.
Raised liver enzymes
Shown to raise the liver enzyme ALT to three times the normal limit or more in 2.0% against 0.3% on placebo in short trials.
The numbers and sources
- How common
- Common: between 1 in 100 and 1 in 10 people.
- Effect
- ALT rose to at least three times the upper limit of normal in 2.0% (8 of 424) on mirtazapine and 0.3% (1 of 328) on placebo. Some people stopped the drug, and in others levels returned to normal while it was continued [7].
- Population
- 424 adults on mirtazapine and 328 on placebo in short-term US trials [7].
- Sources
- [7]
- Caveats
- Short trials, with no rate of liver injury given.
Deaths in a dementia trial
One trial found 7 deaths on mirtazapine against 1 on placebo by week 16 in people with dementia, a difference of marginal statistical significance.
The numbers and sources
- How common
- Common: between 1 in 100 and 1 in 10 people.
- Effect
- In a trial of mirtazapine for agitation in dementia, 7 of 102 people on mirtazapine and 1 of 102 on placebo had died by week 16. A post hoc analysis put the difference at marginal statistical significance (P = 0.065) [12]. In an earlier trial in depression with dementia, five people died in each group by week 39 [13].
- Population
- 204 people with dementia and agitation [12]; people with dementia and depression in a three-arm trial [13].
- Sources
- [12], [13]
- Caveats
- A small number of deaths in one trial, analyzed post hoc and not confirmed in the earlier trial.
Mania or hypomania
The label reports symptoms of mania or hypomania in 0.2% of people treated with mirtazapine in controlled trials that mostly excluded bipolar disorder.
The numbers and sources
- How common
- Uncommon: between 1 in 1,000 and 1 in 100 people.
- Effect
- The label states that treating a depressive episode with an antidepressant may precipitate a mixed or manic episode in people with bipolar disorder, and that mania or hypomania was reported in 0.2% of people on mirtazapine in controlled trials [7].
- Population
- Adults in controlled clinical trials [7].
- Sources
- [7]
- Caveats
- No placebo rate is given beside the 0.2%.
Very low white blood cell count
The label reports agranulocytosis in 2 of 2,796 people in premarketing trials, and severe neutropenia in a third. All three recovered after stopping.
The numbers and sources
- How common
- Rare: fewer than 1 in 1,000 people.
- Effect
- In premarketing trials, 2 of 2,796 people treated with mirtazapine developed agranulocytosis with signs such as fever or infection, one of whom had Sjögren's syndrome, and a third developed severe neutropenia without symptoms. Onset was on days 61, 9 and 14 of treatment, and all three recovered after the drug was stopped [7].
- Population
- 2,796 people in premarketing clinical trials [7].
- Sources
- [7]
- Caveats
- Three cases with no placebo comparison. The band above is for the two cases of agranulocytosis.
Seizures
The label reports 1 seizure among 2,796 people treated with mirtazapine in premarketing trials.
The numbers and sources
- How common
- Rare: fewer than 1 in 1,000 people.
- Effect
- One seizure was reported among 2,796 US and non-US patients in premarketing trials. The label states that mirtazapine has not been systematically evaluated in people with seizure disorders [7].
- Population
- 2,796 people in premarketing clinical trials [7].
- Sources
- [7]
- Caveats
- One case, with no placebo comparison.
QT interval and heart rhythm
The label reports QT interval lengthening rose with mirtazapine blood levels in a 54-person study, below a level considered clinically meaningful, with postmarketing reports of torsades de pointes.
The numbers and sources
- How common
- How often is not known: the sources give no rate.
- Effect
- In a randomized trial in 54 healthy volunteers with placebo and moxifloxacin controls, QTc prolongation rose with mirtazapine concentration. At 45 mg and 75 mg the degree of prolongation was not at a level generally considered clinically meaningful. Cases of QT prolongation and torsades de pointes have been reported in postmarketing use. The label states that other QT-prolonging drugs taken with mirtazapine increase the risk [7].
- Population
- 54 healthy volunteers, and postmarketing reports [7].
- Sources
- [7]
- Caveats
- Postmarketing reports have no denominator.
Serotonin syndrome
The label warns that mirtazapine can precipitate serotonin syndrome, with higher risk alongside other serotonergic drugs. It gives no rate.
The numbers and sources
- How common
- How often is not known: the sources give no rate.
- Effect
- The label names triptans, tricyclic antidepressants, SSRIs, SNRIs, fentanyl, lithium, tramadol, tryptophan, buspirone, amphetamines and St. John's wort as raising the risk [7].
- Population
- Labeling statement [7].
- Sources
- [7]
- Caveats
- A label warning with no denominator.
Use with MAOIs
The label lists MAOIs as a contraindication because the combination increases the risk of serotonin syndrome. It gives no rate.
The numbers and sources
- How common
- How often is not known: the sources give no rate.
- Effect
- The label states that mirtazapine is contraindicated with monoamine oxidase inhibitors or within 14 days of stopping one. Its examples are selegiline, tranylcypromine, isocarboxazid, phenelzine, the antibiotic linezolid and intravenous methylene blue [7].
- Population
- Labeling statement [7].
- Sources
- [7]
- Caveats
- The label gives no rate.
Alcohol and benzodiazepines
The label states that benzodiazepines or alcohol taken with mirtazapine increase the impairment of thinking and motor skills beyond mirtazapine alone. It gives no rate.
The numbers and sources
- How common
- How often is not known: the sources give no rate.
- Effect
- The label lists diazepam, alprazolam and alcohol as examples that add to the impairment of cognitive and motor skills produced by mirtazapine [7].
- Population
- Labeling statement drawn from interaction studies [7].
- Sources
- [7]
- Caveats
- No numbers are given for the size of the added impairment.
Drugs that change mirtazapine levels
The label states that strong inducers of a liver enzyme lower mirtazapine blood levels, and that strong inhibitors and cimetidine may raise them.
The numbers and sources
- How common
- How often is not known: the sources give no rate.
- Effect
- The label states that strong CYP3A inducers, with phenytoin, carbamazepine and rifampin as examples, decrease the plasma concentration of mirtazapine. Strong CYP3A inhibitors, with itraconazole, ritonavir and nefazodone as examples, and the acid reducer cimetidine may increase it [7].
- Population
- Labeling statements drawn from drug interaction studies [7].
- Sources
- [7]
- Caveats
- Changes in drug levels, with no rate of harm.
Symptoms after stopping
The label reports dizziness, abnormal dreams, electric shock sensations, agitation, anxiety, nausea and sweating after stopping mirtazapine, particularly abruptly. It gives no rate.
The numbers and sources
- How common
- How often is not known: the sources give no rate.
- Effect
- The label lists dizziness, abnormal dreams, sensory disturbances including paresthesia and electric shock sensations, agitation, anxiety, fatigue, confusion, headache, tremor, nausea, vomiting and sweating after discontinuation [7]. Across antidepressants as a group, a meta-analysis found at least one discontinuation symptom in 31% of people stopping a drug and 17% stopping placebo, and severe symptoms in 2.8% against 0.6% [15].
- Population
- Reports summarized in labeling [7]; 21,002 patients in 79 studies of antidepressants [15].
- Sources
- [7], [15]
- Caveats
- The abstract of [15] names no figure for mirtazapine, so the pooled rate is context and not a mirtazapine rate. No study of misuse or dependence on mirtazapine was sourced.
Severe skin reactions
The label reports severe skin reactions after mirtazapine, including drug reaction with eosinophilia and systemic symptoms, Stevens-Johnson syndrome and toxic epidermal necrolysis. It gives no rate.
The numbers and sources
- How common
- How often is not known: the sources give no rate.
- Effect
- The label states that drug reaction with eosinophilia and systemic symptoms, Stevens-Johnson syndrome, bullous dermatitis, erythema multiforme and toxic epidermal necrolysis have been reported following use [7].
- Population
- Reports summarized in labeling [7].
- Sources
- [7]
- Caveats
- Reports with no denominator.
Mixed results1
Pregnancy
Mixed results: most studies found outcomes like those in unexposed pregnancies, findings on birth defects and miscarriage conflicted, and newborn adaptation symptoms followed late exposure.
The numbers and sources
- How common
- How often is not known: the sources give no rate.
- Effect
- A systematic review of 41 studies found outcomes in mirtazapine-exposed pregnancies comparable to controls in most studies, conflicting results on congenital malformations and spontaneous abortion, and reports of neonatal adaptation syndrome after exposure late in pregnancy [17]. The label states that published observational studies and postmarketing reports have not reliably identified a drug-associated risk of major birth defects, miscarriage or adverse maternal or fetal outcomes [7].
- Population
- 15 cohort studies, one case-control study, 11 case series and 14 case reports [17].
- Sources
- [17], [7]
- Caveats
- The review rated the overall quality of evidence low, and found too little data on breastfeeding to draw conclusions.
Checked, no increase found1
Sexual side effects
Not shown to raise sexual dysfunction above placebo in a meta-analysis, and less likely to cause it than SSRIs in head-to-head depression trials.
The numbers and sources
- How common
- How often is not known: the sources give no rate.
- Effect
- A meta-analysis of treatment-emergent sexual dysfunction found no significant difference from placebo for mirtazapine, while ten other antidepressants had rates from 25.8% to 80.3% [16]. In a Cochrane review, mirtazapine was less likely than SSRIs to cause sexual dysfunction [2].
- Population
- Studies of antidepressants reporting sexual dysfunction [16]; 2,626 participants in 12 trials against SSRIs [2].
- Sources
- [16], [2]
- Caveats
- The abstracts give no rate for mirtazapine. The meta-analysis included open-label studies and varied rating scales.
Claims tested and not found
- That mirtazapine restores appetite in people with cancer. Appetite scores did not differ from placebo after 28 days in 100 patients with incurable solid tumors [5], or at 4 and 8 weeks in 86 patients with advanced lung cancer [6].
- That adding mirtazapine helps when an SSRI or SNRI has not. In a placebo-controlled primary care trial, depression scores at 12 weeks did not clearly differ (adjusted difference -1.83, 95% CI -3.92 to 0.27) [11].
- That mirtazapine calms agitation in dementia. In 204 people, agitation scores at 12 weeks did not differ from placebo [12].
- That mirtazapine treats depression in people with dementia. Depression scores at 13 and 39 weeks did not differ from placebo, and adverse reactions were more frequent [13].
- That low-dose mirtazapine keeps helping insomnia for months. Insomnia scores were lower than placebo at 6 weeks and no longer differed from 12 weeks onward [3].
Sources
- Cipriani A, Furukawa TA, Salanti G, et al. Comparative efficacy and acceptability of 21 antidepressant drugs for the acute treatment of adults with major depressive disorder: a systematic review and network meta-analysis. The Lancet. 2018. https://doi.org/10.1016/S0140-6736(17)32802-7
- Watanabe N, Omori IM, Nakagawa A, et al. Mirtazapine versus other antidepressive agents for depression. Cochrane Database of Systematic Reviews. 2011. https://doi.org/10.1002/14651858.CD006528.pub2
- Bakker MH, Hugtenburg JG, Bet PM, et al. Effectiveness of low-dose amitriptyline and mirtazapine in patients with insomnia disorder and sleep maintenance problems: a randomised, double-blind, placebo-controlled trial in general practice (DREAMING). British Journal of General Practice. 2025. https://doi.org/10.3399/bjgp.2024.0173
- Nguyen PV, Dang-Vu TT, Forest G, et al. Mirtazapine for chronic insomnia in older adults: a randomised double-blind placebo-controlled trial, the MIRAGE study. Age and Ageing. 2025. https://doi.org/10.1093/ageing/afaf050
- Hunter CN, Abdel-Aal HH, Elsherief WA, et al. Mirtazapine in Cancer-Associated Anorexia and Cachexia: A Double-Blind Placebo-Controlled Randomized Trial. Journal of Pain and Symptom Management. 2021. https://doi.org/10.1016/j.jpainsymman.2021.05.017
- Arrieta O, Cárdenas-Fernández D, Rodriguez-Mayoral O, et al. Mirtazapine as Appetite Stimulant in Patients With Non-Small Cell Lung Cancer and Anorexia: A Randomized Clinical Trial. JAMA Oncology. 2024. https://doi.org/10.1001/jamaoncol.2023.5232
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