Drug profile

The FDA adverse-event record for Acetylcysteine

44 adverse-event reports submitted to the FDA Center for Veterinary Medicine reference Acetylcysteine. Species, reactions, and outcomes follow.

#1199 of 2,679
by report volume (all drugs)
44
adverse-event reports
56.8%
death-coded share
Dog
most-reported species
Verify with FDA CVM →

Corpus placement

According to the FDA Center for Veterinary Medicine openFDA adverse-event extract, Acetylcysteine ranks #1198 of 2679 by total reports (44). Death-coded-share rank requires at least 50 reports. 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)
#1198
This drug, reports of 2679

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. Acetylcysteine has 44 reports now versus 39 in that prior snapshot: 5 more (12.8%).

Report change
+5
Death-coded reports
+3
Death-coded share
+0.4 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 Acetylcysteine changes

Signature read: Acetylcysteine's 56.8% death-coded share is among the highest in the openFDA drug corpus.

Important: Adverse event reports do not establish that a drug caused or contributed to the event. Consult your veterinarian before making treatment decisions.
44
Total Reports
25
Deaths Reported
56.8%
Death-coded share of reports

Active Ingredients

Acetylcysteine

Administration Routes

UnknownIntravenousOralParenteral

Species Affected

Dog 39
Cat 4
Horse 1

Most Affected Breeds

Crossbred Canine/dog 4
Shepherd Dog - German 4
Domestic Shorthair 4
Retriever - Golden 4
Poodle (unspecified) 3
Corgi - Welsh Pembroke 3
Siberian Husky 3
Dog (other) 2
Retriever - Labrador 2
Pit Bull 2

Most Reported Reactions

Elevated alanine aminotransferase (ALT) 21
Elevated total bilirubin 21
Abnormal ultrasound finding 18
Death by euthanasia 14
Vomiting 13
Lethargy (see also Central nervous system depression in Neurological) 13
Hypokalaemia 12
Elevated serum alkaline phosphatase (ALP) 12
Death 11
Icterus 11
Other abnormal test result NOS 11
Not eating 10

Outcome Breakdown

Euthanized
14 (30.4%)
Ongoing
12 (26.1%)
Died
11 (23.9%)
Outcome Unknown
7 (15.2%)
Recovered/Normal
1 (2.2%)
Recovered with Sequela
1 (2.2%)

Acetylcysteine: high death-coded share 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.

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 Acetylcysteine (#1199 of 2,679 by report volume); death-coded 56.8%. PlainBreed drug row · death-coded share stamp 56.8% · 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 →