Drug profile

The FDA adverse-event record for Melatonin

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

#471 of 2,679
by report volume (all drugs)
255
adverse-event reports
11.4%
death-coded share
Dog
most-reported species

Corpus placement

According to the FDA Center for Veterinary Medicine openFDA adverse-event extract, Melatonin ranks #470 of 2679 by total reports (255) and #487 of 1130 by death-coded share (11.4%). 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)
#470
This drug, reports of 2679
#487
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. Melatonin has 255 reports now versus 245 in that prior snapshot: 10 more (4.1%).

Report change
+10
Death-coded reports
+0
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 Melatonin changes

Signature read: death-coded report count at 29 is the most distinctive stamp on Melatonin'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.
255
Total Reports
29
Deaths Reported
11.4%
Death-coded share of reports

Active Ingredients

Melatonin

Administration Routes

OralUnknownSubcutaneous

Species Affected

Dog 250
Cat 2
Human 2
Pig 1

Most Affected Breeds

Retriever - Labrador 28
Boxer (German Boxer) 14
Spitz - German Pomeranian 11
Shih Tzu 10
Crossbred Canine/dog 10
Chihuahua 7
Maltese 7
Dachshund (unspecified) 7
Terrier - West Highland White 7
Shepherd Dog - German 6

Most Reported Reactions

Diarrhoea 38
Vomiting 35
Lethargy (see also Central nervous system depression in 'Neurological') 28
Decreased appetite 24
Polydipsia 22
Weight loss 21
Other abnormal test result NOS 21
Death by euthanasia 21
Polyuria 20
Elevated alanine aminotransferase (ALT) 20
Anorexia 20
Lethargy (see also Central nervous system depression in Neurological) 18

Outcome Breakdown

Ongoing
89 (34.9%)
Outcome Unknown
71 (27.8%)
Recovered/Normal
63 (24.7%)
Euthanized
20 (7.8%)
Died
9 (3.5%)
Recovered with Sequela
3 (1.2%)

Melatonin: 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 Melatonin, 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 Melatonin (#471 of 2,679 by report volume); death-coded 11.4%. PlainBreed drug row · death-coded report count stamp 29 · 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 →