Drug profile

The FDA adverse-event record for Melatonin

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

236
adverse-event reports
12.3%
death-coded share
Dog
most-reported species
35
Diarrhoea - 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.
236
Total Reports
29
Deaths Reported
12.3%
Death Rate

Active Ingredients

Melatonin

Administration Routes

OralUnknownSubcutaneous

Species Affected

Dog 231
Cat 2
Human 2
Pig 1

Most Affected Breeds

Retriever - Labrador 28
Boxer (German Boxer) 14
Shih Tzu 10
Spitz - German Pomeranian 9
Crossbred Canine/dog 8
Chihuahua 7
Maltese 7
Dachshund (unspecified) 7
Shepherd Dog - German 6
Bulldog 6

Most Reported Reactions

Diarrhoea 35
Vomiting 32
Lethargy (see also Central nervous system depression in 'Neurological') 28
Decreased appetite 23
Polydipsia 22
Death by euthanasia 21
Polyuria 20
Weight loss 20
Other abnormal test result NOS 20
Anorexia 20
Elevated alanine aminotransferase (ALT) 18
Emesis 17

Outcome Breakdown

Ongoing
80 (33.9%)
Outcome Unknown
66 (28.0%)
Recovered/Normal
59 (25.0%)
Euthanized
20 (8.5%)
Died
9 (3.8%)
Recovered with Sequela
2 (0.8%)

Melatonin Adverse Event Insights

236 reports name Melatonin; 29 recorded a death outcome (12.3% of reported events, not a population-level mortality rate). Active ingredient: Melatonin. Administration routes: Oral, Unknown, Subcutaneous.

By species: Dog (231 reports), Cat (2 reports), Human (2 reports). By breed: Retriever - Labrador (28), Boxer (German Boxer) (14), Shih Tzu (10).

Leading clinical signs: Diarrhoea (35), Vomiting (32), Lethargy (see also Central nervous system depression in 'Neurological') (28), Decreased appetite (23). Outcome, 236 coded reports: Ongoing leads at 33.9%.

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.