Olanzapine vs Mirtazapine: side effects in FDA adverse event reports
At a glance
| Olanzapine | Mirtazapine | |
|---|---|---|
| Drug class | Atypical Antipsychotic | – |
| Brand names | – | – |
| FAERS reports | 106,808 | 91,033 |
| Serious | 86% | 84% |
| Death outcome | 13,180 | 13,998 |
| Boxed warning | Yes INCREASED MORTALITY IN ELDERLY PATIENTS WITH DEMENTIA-RELATED PSYCHOSIS Elderly patients with dementia-related psychosis treated with antipsychotic drugs are at | Yes SUICIDAL THOUGHTS AND BEHAVIORS Antidepressants increased the risk of suicidal thoughts and behaviors in pediatric and young adult patients in short-term studie |
Signals both drugs share
| Reaction | Olanzapine | Mirtazapine | Label screen (A / B) |
|---|---|---|---|
| Neuroleptic malignant syndrome | 2,718 · PRR 58.1 | 515 · PRR 10.4 | Labeled — boxed warning / Not in label — unassessed |
| Akathisia | 1,619 · PRR 26.3 | 487 · PRR 8.5 | Labeled adverse reaction / Labeled adverse reaction |
| Anticholinergic syndrome | 236 · PRR 34.0 | 165 · PRR 26.5 | Labeled (related wording) / Not in label — unassessed |
| Cogwheel rigidity | 154 · PRR 33.5 | 107 · PRR 25.9 | Labeled adverse reaction / Not in label — unassessed |
| Delusion of grandeur | 122 · PRR 73.5 | 72 · PRR 44.0 | Not in label — unassessed / Not in label — unassessed |
Labeled signals distinctive to Olanzapine
- Schizophrenia — n=2,234, PRR 44.1 Labeled — boxed warning
- Metabolic disorder — n=1,229, PRR 52.6 Labeled (related wording)
- Parkinsonism — n=1,188, PRR 27.1 Labeled adverse reaction
- Diabetic coma — n=616, PRR 54.6 Labeled adverse reaction
- Diabetes mellitus non-insulin-dependent — n=594, PRR 133.1 Labeled (related wording)
- Schizoaffective disorder — n=531, PRR 82.6 Labeled adverse reaction
- Metabolic syndrome — n=407, PRR 64.6 Labeled (related wording)
- Oculogyric crisis — n=347, PRR 38.6 Labeled adverse reaction
Labeled signals distinctive to Mirtazapine
- Serotonin syndrome — n=1,332, PRR 17.2 Labeled — boxed warning
- Inappropriate antidiuretic hormone secretion — n=415, PRR 9.7 Labeled adverse reaction
- Major depression — n=290, PRR 9.5 Labeled (related wording)
- Urinary tract disorder — n=205, PRR 11.0 Labeled (related wording)
- Hallucinations, mixed — n=180, PRR 10.2 Labeled (related wording)
- Depressive symptom — n=144, PRR 9.8 Labeled (related wording)
- Anxiety disorder — n=125, PRR 8.9 Labeled (related wording)
- Systemic infection — n=92, PRR 13.4 Labeled (related wording)
Common questions
Which has more reported side effects, Olanzapine or Mirtazapine?
Olanzapine has 106,808 FAERS reports and Mirtazapine 91,033. More reports does not mean more dangerous: volume follows how widely and how long a drug has been used, prescription vs over-the-counter status, and publicity. The seriousness share (86% vs 84%) is a better like-for-like signal of the kind of problems reported.
Which side effects do Olanzapine and Mirtazapine share?
Both drugs carry disproportionality signals for neuroleptic malignant syndrome, akathisia, anticholinergic syndrome, cogwheel rigidity, delusion of grandeur. Shared signals often reflect a shared drug class or the condition both are used for.
Is Olanzapine or Mirtazapine safer?
FAERS cannot answer that: it has no denominator and no comparator. Use this page to see which risks are already on each label and which signals are unlabeled, then check the prescribing information and your clinician for your situation.
Sources: openFDA FAERS pair statistics (OpenPV build 2026-09-14), FDA labels via openFDA, openFDA count queries for seriousness and deaths. Pair chosen because it is a commonly searched comparison. Generated 2026-10-08.