Drug profile

The FDA adverse-event record for Mirtazapine

2,444 adverse-event reports submitted to the FDA Center for Veterinary Medicine reference Mirtazapine. See the species affected, top reactions, and outcomes below.

2,444
adverse-event reports
17.3%
death-coded share
Cat
most-reported species
276
Death by euthanasia - top reaction
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Important: Adverse event reports do not establish that a drug caused or contributed to the event. Consult your veterinarian before making treatment decisions.
2,444
Total Reports
424
Deaths Reported
17.3%
Death Rate

Active Ingredients

Mirtazapine

Administration Routes

UnknownTransdermalOralTopicalIntradermalAuricular (Otic)OphthalmicOtherRespiratory (Inhalation)Cutaneous

Species Affected

Cat 1,593
Unknown 540
Dog 257
Human 50
Other 2
Tiger 1
Fallow 1

Most Affected Breeds

Domestic Shorthair 894
Unknown 596
Cat (unknown) 210
Domestic Longhair 141
Siamese 68
Domestic Mediumhair 60
Maine Coon 37
Retriever - Labrador 35
Ragdoll 26
Persian 22

Most Reported Reactions

Death by euthanasia 276
Lack of efficacy - NOS 256
Appearance, Abnormal 251
Vomiting 246
Anorexia 201
Weight loss 193
Lethargy (see also Central nervous system depression in 'Neurological') 183
Not eating 148
Diarrhoea 141
Death 140
Application site reddening 139
Decreased appetite 136

Outcome Breakdown

Outcome Unknown
631 (33.1%)
Recovered/Normal
496 (26.0%)
Ongoing
348 (18.2%)
Euthanized
277 (14.5%)
Died
149 (7.8%)
Recovered with Sequela
7 (0.4%)

Mirtazapine Adverse Event Insights

2,444 reports name Mirtazapine; 424 recorded a death outcome (17.3% of reported events, not a population-level mortality rate). Active ingredient: Mirtazapine. Administration routes: Unknown, Transdermal, Oral, Topical.

By species: Cat (1,593 reports), Unknown (540 reports), Dog (257 reports). By breed: Domestic Shorthair (894), Unknown (596), Cat (unknown) (210).

Leading clinical signs: Death by euthanasia (276), Lack of efficacy - NOS (256), Appearance, Abnormal (251), Vomiting (246). Outcome, 1,908 coded reports: Outcome Unknown leads at 33.1%.

Read these counts as reporting volume, not risk: per our methodology, a widely-prescribed drug will rack up more raw FDA reports in a given year than a rarely-used one at an identical true rate, so we recommend comparing within similar-exposure products rather than across the full 2025 catalog.

Source: FDA Center for Veterinary Medicine openFDA Animal & Veterinary Adverse Events (CVM AER) · 2025

Every figure on PlainBreed is rendered directly from FDA openFDA adverse event data, no number is typed in by an editor. This page draws directly on FDA openFDA data, no figure is typed in by an editor. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error.