Drug profile

The FDA adverse-event record for Mirtazapine

2,828 FDA reports name Mirtazapine, a high-volume drug in the CVM extract. Species, reactions, and outcomes follow.

#80 of 2,679
by report volume (all drugs)
2,828
adverse-event reports
16.3%
death-coded share
Cat
most-reported species

Corpus placement

According to the FDA Center for Veterinary Medicine openFDA adverse-event extract, Mirtazapine ranks #80 of 2679 by total reports (2,828) and #331 of 1130 by death-coded share (16.3%). National dual: Milbemycin Oxime + Spinosad is #1 of 2679 drugs by total adverse-event reports (149,624) at death-coded-share rank 965 of 1130 drugs with at least 50 reports (2.3%); separately, Atlantic Salmon Transgenic Whole (Opafp-Ghc2 Rdna Construct Inserted Into The A-Locus In The Eo-1A Lineage) is #1 highest death-coded share at 97.8% (report rank #821).

149,624
Milbemycin Oxime + Spinosad reports (#1)
97.8%
Atlantic Salmon Transgenic Whole (Opafp-Ghc2 Rdna Construct Inserted Into The A-Locus In The Eo-1A Lineage) death share (#1)
#80
This drug, reports of 2679
#331
This drug, death share of 1130

Report volume reflects how common a breed or drug is and how often owners and vets file — not actual risk. Death-coded share ranks are limited to entries with enough reports to be meaningful. The two maps do not agree at #1.

Release-over-release change

What changed in the latest FDA data snapshot

PlainBreed reconstructed the prior snapshot from dated openFDA partitions through 2025 Q4, then compared it with the 2026-07-27 openFDA export. Mirtazapine has 2,828 reports now versus 2,654 in that prior snapshot: 174 more (6.6%).

Report change
+174
Death-coded reports
+16
Death-coded share
−0.5 pts

This compares reported-event counts in two source snapshots. It does not establish a change in real-world risk, product safety, or disease incidence.

Subscribe to Mirtazapine changes

Signature read: death-coded report count at 460 is the most distinctive stamp on Mirtazapine's FDA AER row.

Important: Adverse event reports do not establish that a drug caused or contributed to the event. Consult your veterinarian before making treatment decisions.
2,828
Total Reports
460
Deaths Reported
16.3%
Death-coded share of reports

Active Ingredients

Mirtazapine

Administration Routes

UnknownTransdermalOralTopicalIntradermalAuricular (Otic)OphthalmicOtherRespiratory (Inhalation)Cutaneous

Species Affected

Cat 1,781
Unknown 715
Dog 274
Human 54
Other 2
Tiger 1
Fallow 1

Most Affected Breeds

Domestic Shorthair 1,001
Unknown 776
Cat (unknown) 220
Domestic Longhair 163
Domestic Mediumhair 76
Siamese 70
Maine Coon 41
Retriever - Labrador 38
Ragdoll 29
Persian 24

Most Reported Reactions

Lack of efficacy - NOS 301
Death by euthanasia 294
Vomiting 277
Appearance, Abnormal 267
Product defect, product difficult to use/handle (see also 'Drug device difficult to use/handle') 253
Tubes, Leaking 236
Weight loss 217
Anorexia 214
Not eating 187
Lethargy (see also Central nervous system depression in 'Neurological') 183
Diarrhoea 164
Application site reddening 160

Outcome Breakdown

Outcome Unknown
698 (32.9%)
Recovered/Normal
534 (25.2%)
Ongoing
416 (19.6%)
Euthanized
295 (13.9%)
Died
168 (7.9%)
Recovered with Sequela
8 (0.4%)

Mirtazapine: high report volume in the FDA AER row

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.

High-volume nationwide drug peers

Two openFDA-derived peer sets for Mirtazapine, both floored at ≥50 reports so the neighborhoods stay in the advertised mass.

What to do with this drug

A report does not prove a drug caused the reaction; consult a veterinarian before acting on this data.

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

openFDA Animal & Veterinary Adverse Events (FDA CVM) for Mirtazapine (#80 of 2,679 by report volume); death-coded 16.3%. PlainBreed drug row · death-coded report count stamp 460 · vintage 2025.

Informational only. FDA adverse-event reports are voluntary and do not prove causation; consult a veterinarian before acting on them. Verify with FDA CVM →