Melatonin (PrimeX): adverse event reports that FDA received

Name: Melatonin: adverse event reports that FDA received, by year and species
Creator: Pet Drug Reports
License: https://creativecommons.org/publicdomain/zero/1.0/

Active ingredient

The name in brackets is a brand name with this active ingredient.

The openFDA records give the value "MSK" for the brand name and for the manufacturer name of each drug. FDA says that MSK means "masked". So the site cannot count a report for a brand.

Read this first. FDA says this about the data:

An API dataset query result cannot be used to estimate the risk associated with the product or compare one drug or device product with another. When looking at the results, be aware that there is no certainty that the reported drug or device caused the adverse event. This dataset should not be the sole source of information for clinical decision-making or other assumptions about the safety or effectiveness of a product. The adverse event may have been related to an underlying disease, other drugs used at the same time or other non-drug related sources.
FDA Center for Veterinary Medicine publishes these words. Source: Adverse Event Reports for Animal Drugs and Devices, read on 2 Oct 2026. The data have the reports that FDA received through 26 Jun 2026.

This page is not veterinary advice. For an animal that is ill, speak to a veterinarian.

Contacting a veterinarian How to report to FDA

From June 2008 to June 2026, FDA received 283 adverse event reports that name a drug with melatonin as its active ingredient. Of the 283 reports, 276 (97.5%) are about dogs. 3 reports are about cats (1.1%).

In January to March 2026, FDA received 11 reports that name this drug. The signs that appear in the largest number of the 283 reports are "Lethargy", "Diarrhoea" and "Vomiting". A report is not proof that a drug caused a sign.

Reports that name this drug fell by 5.4% in the 12 months to June 2026, compared with the 12 months before. Reports for all animal drugs fell by 4.6% in the same periods. The newest months can get more reports in a later update. Reports about dogs are 97.5% of the reports that name this drug, and 72.6% of all reports.

Search engines list a drug page with 500 reports or more in all years. The page also needs 30 reports or more in the 12 months to June 2026. This page is under one of these numbers. The site keeps the page and keeps it out of search engines.

Since the last update of the FDA data

The latest update of the FDA data, recorded on 11 Oct 2026, changed no count of this page.

January to March 2026 is the latest closed quarter in the data. In that quarter FDA received 11 reports that name melatonin: 11 dog, 0 cat, 0 horse, 0 other or not given.

All updates Feed of updates (RSS)

Signs that the reports list

A sign is a coded term from the report. The words in brackets are a plain gloss of the term. The percentage is the share of the 283 reports that list the sign. One report can list more than one sign.

The sign that is in the largest number of the reports comes first.

Lethargy[unusually tired or inactive]17.3%49 reports
Diarrhoea[diarrhea]14.5%41 reports
Vomiting14.5%41 reports
Decreased appetite9.5%27 reports
Death by euthanasia[the animal was euthanized]7.8%22 reports
Other abnormal test result NOS[abnormal laboratory result, type not specified]7.8%22 reports
Weight loss7.8%22 reports
Elevated alanine aminotransferase (ALT)[a liver enzyme above the normal range]7.4%21 reports
Polydipsia[drinking more than usual]7.4%21 reports
Anorexia[not eating]6.7%19 reports
Emesis[vomiting]6.7%19 reports
Polyuria[passing more urine than usual]6.7%19 reports
Not eating6.4%18 reports
Elevated serum alkaline phosphatase (SAP)[a liver and bone enzyme above the normal range]4.9%14 reports

Show the next 16 signs

Lack of efficacy - NOS[the product did not have the expected effect]4.9%14 reports
Elevated blood urea nitrogen (BUN)[a kidney value above the normal range]4.6%13 reports
Anaemia NOS[low red blood cell count]4.2%12 reports
Seizure NOS[seizure, type not specified]4.2%12 reports
Ataxia[unsteady, uncoordinated movement]3.9%11 reports
Behavioural disorder NOS[behaviour change, type not specified]3.9%11 reports
Limb weakness3.9%11 reports
Not drinking3.5%10 reports
Thrombocytopenia[low platelet count]3.5%10 reports
Elevated gamma-glutamyl transferase (GGT)[a liver enzyme above the normal range]3.2%9 reports
Immune mediated haemolytic anaemia[the immune system destroying red blood cells]3.2%9 reports
Immune mediated thrombocytopenia3.2%9 reports
Leucocytosis NOS[high white blood cell count]3.2%9 reports
Panting3.2%9 reports
Abnormal ultrasound finding2.8%8 reports
Collapse NOS[NOS: not otherwise specified]2.8%8 reports

The list shows 30 of 516 coded signs. A report is not proof that a drug caused a sign. Download all signs (CSV)

Reports by species

Dog97.5%276
Cat1.1%3
Human exposure0.7%2
Pig0.4%1

The share is of all 283 reports that name melatonin. The other reports give a different species or no species.

Reports for each month, Jul 2021 to Jun 2026

Dog134 reports. Largest count in one month: 8 (Sep 2023)

Cat2 reports

No chart: no month has 5 or more reports.

Horse0 reports

No chart: no month has 5 or more reports.

Other or not given1 report

No chart: no month has 5 or more reports.

The month is the month in which FDA received the report. Each chart has its own scale. FDA says that a report can take 3 to 6 months to reach the public data. The newest months can get more reports in a later update.

Reports by year

Dog
Cat
Horse
Other or not given

Reports that name melatonin, by the year in which FDA received them and by species
Year	Dog	Cat	Other or not given	All species
2026	19	0	0	19
2025	30	0	0	30
2024	40	2	0	42
2023	33	0	0	33
2022	10	0	0	10
2021	12	0	2	14
2020	18	0	2	20
2019	16	0	0	16
2018	16	0	0	16
2017	7	1	0	8
2016	15	0	0	15
2015	16	0	0	16
2014	10	0	0	10
2013	22	0	0	22
2012	9	0	0	9
2011	2	0	0	2
2008	1	0	0	1

2026 has the reports that FDA received through Jun 2026. Download the years (CSV)

What the reports record

Outcome at the time of the report

Recovered/Normal23.7%67
Recovered with Sequela[recovered, with a lasting effect]1.1%3
Ongoing35%99
Died3.5%10
Euthanized7.4%21
Outcome Unknown28.6%81

An outcome in a report is not proof that the drug caused it. The person who sends the report gives the outcome. Each share is of the 283 reports that name melatonin.

A report about more than one animal can have more than one outcome.

Kind of report

Safety issue85.2%241
Lack of expected effectiveness5.3%15
Both safety and lack of expected effectiveness7.1%20
Manufacturing or product defect2.5%7
Other0%0

272 reports say if the event was serious. 48.5% of them have the serious flag. The person who sends the report sets the flag.

Show age, weight, breed and route

Age of the animal

Under 1 year1.4%4
1 to 3 years11%31
4 to 7 years18.7%53
8 to 11 years25.4%72
12 years and over42%119
Age not given1.4%4

Weight of the animal

Under 5 kg (11 lb)11.3%32
5 to 9.9 kg (11 to 22 lb)24.4%69
10 to 24.9 kg (22 to 55 lb)26.1%74
25 to 44.9 kg (55 to 99 lb)29.7%84
45 kg and over (99 lb and over)4.6%13
Weight not given3.9%11

Breed, where the report gives one breed

A breed with many animals has many reports.

Route in the report

Oral57.2%162
Subcutaneous0.7%2

Each bar is on a scale of 0 to 100%.

Approved animal drugs with this active ingredient (FDA Green Book)

This section is reference data. It has no report count.

The openFDA records give the value "MSK" for the brand name and for the manufacturer name of each drug. FDA says that MSK means "masked". So the site cannot count a report for a brand.

Brand names

PrimeX

What the Green Book records give

Applications with an approval in force: 1
Approved species: Mustelids (Weasel Family)
Dose forms: Implant
Routes: Subcutaneous
Sale: OTC (over the counter)
Earliest approval date in the records: 21 Jun 1994

The species, dose forms and routes are the words of the Green Book records for all the applications together. One product can have fewer. The label of a product gives its approved use.

Applications in the Green Book of 2 Nov 2026, pioneer applications (NADA) first
Brand name	Active ingredients	Sponsor	Approved species	Application
PrimeX	Melatonin	Neo Dynamics LLP	Not in the list of major species	NADA 140-846

Next in the A to Z list

All drugs by active ingredient. Brand names A to Z

FDA pages for this drug

How to Report Animal Drug and Device Side Effects and Product ProblemsThe FDA page that tells an owner or a veterinarian how to send a report.
Green Book record of NADA 140-846The FDA record of the application for PrimeX.
Animal Drugs @ FDAThe search page of the Green Book, the FDA list of approved animal drugs.

The site checked these addresses on 2 Oct 2026. The links open in a new tab.

Cite this page

Pet Drug Reports. Melatonin: adverse event reports that FDA received. https://petdrugreports.com/drug/melatonin/ Source: FDA Center for Veterinary Medicine, openFDA Animal and Veterinary adverse event reports, export of 30 Oct 2026. Reports received through 26 Jun 2026.

Where the data come from

The counts come from the openFDA Animal and Veterinary adverse event files, export of 30 Oct 2026. The files have the reports that the FDA Center for Veterinary Medicine received through 26 Jun 2026. The files mask brand and manufacturer names. The site counts a drug by the active ingredients that each record gives, and gives no count to a brand, an application or a company. Ingredient names and the lists of approved products follow the FDA Green Book of 2 Nov 2026. The site does not use the application number that a record has.

The site does not publish report text, lot numbers or details of a reporter. FDA's record is the authority. See how the site counts reports, the data sources and the corrections page.

Questions about these reports

Which brand are these reports about?: The openFDA records give the value "MSK" for the brand name and for the manufacturer name of each drug. FDA says that MSK means "masked". So the site cannot count a report for a brand. The Green Book section of this page lists the brand names with this active ingredient.
Do the reports show that the drug caused the signs?: No. FDA states this about the data.
When looking at the results, be aware that there is no certainty that the reported drug or device caused the adverse event.
The adverse event may have been related to an underlying disease, other drugs used at the same time or other non-drug related sources.
FDA Center for Veterinary Medicine. Source: Adverse Event Reports for Animal Drugs and Devices
How many reports did FDA receive in the latest 12 months?: FDA received 35 reports in the 12 months to June 2026. It received 37 reports in the 12 months before. FDA says that a report can take 3 to 6 months to reach the public data. The newest months can get more reports in a later update.
What kinds of report are in the count?: Of the 283 reports received from June 2008 to June 2026, 85.2% are about a safety issue only. 12.4% are about a lack of expected effectiveness, alone or with a safety issue. 2.5% are about a defect of the product or its package.