Drug profile

The FDA adverse-event record for Lysine

107 FDA reports name Lysine, a high-volume drug in the CVM extract. Species, reactions, and outcomes follow.

#758 of 2,679
by report volume (all drugs)
107
adverse-event reports
18.7%
death-coded share
Cat
most-reported species

Corpus placement

According to the FDA Center for Veterinary Medicine openFDA adverse-event extract, Lysine ranks #755 of 2679 by total reports (107) and #265 of 1130 by death-coded share (18.7%). 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)
#755
This drug, reports of 2679
#265
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. Lysine has 107 reports now versus 105 in that prior snapshot: 2 more (1.9%).

Report change
+2
Death-coded reports
+0
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 Lysine changes

Signature read: death-coded report count at 20 is the most distinctive stamp on Lysine'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.
107
Total Reports
20
Deaths Reported
18.7%
Death-coded share of reports

Active Ingredients

Lysine

Administration Routes

UnknownOralTopical

Species Affected

Cat 104
Dog 2
Cattle 1

Most Affected Breeds

Domestic Shorthair 60
Domestic Mediumhair 9
Domestic Longhair 5
Cat (unknown) 4
American Curl Shorthair 4
Persian 3
Ragdoll 3
Siamese 3
Cat (other) 3
Bengal 2

Most Reported Reactions

Vomiting 19
Lethargy (see also Central nervous system depression in 'Neurological') 17
Lack of efficacy - NOS 16
Behavioural disorder NOS 10
Decreased appetite 10
Anorexia 10
Death by euthanasia 9
Vocalisation 8
Ataxia 8
Death 8
Other abnormal test result NOS 7
Weight loss 7

Outcome Breakdown

Ongoing
38 (35.2%)
Outcome Unknown
32 (29.6%)
Recovered/Normal
18 (16.7%)
Died
11 (10.2%)
Euthanized
9 (8.3%)

Lysine: 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.

High-volume nationwide drug peers

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

Similar death-coded share

Nearest other drugs by death-coded share (18.7% here), distinct from the volume row.

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 Lysine (#758 of 2,679 by report volume); death-coded 18.7%. PlainBreed drug row · death-coded report count stamp 20 · 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 →