Drug profile

The FDA adverse-event record for Melengestrol Acetate

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

279
adverse-event reports
16.5%
death-coded share
Cattle
most-reported species
110
INEFFECTIVE, ESTRUS SUPPRESSIO - top reaction
Verify with FDA CVM →
Important: Adverse event reports do not establish that a drug caused or contributed to the event. Consult your veterinarian before making treatment decisions.
279
Total Reports
46
Deaths Reported
16.5%
Death Rate

Active Ingredients

Melengestrol Acetate

Administration Routes

OralUnknown

Species Affected

Cattle 256
Unknown 22
Human 1

Most Affected Breeds

Mixed (Cattle) 121
Cattle (other) 46
Cattle (unknown) 42
Crossbred Bovine/Cattle 24
Unknown 24
Holstein-Friesian also known as Holstein 8
Aberdeen Angus 7
Charolais 2
Simmental 1
Jersey 1

Most Reported Reactions

INEFFECTIVE, ESTRUS SUPPRESSIO 110
Lack of efficacy - NOS 79
Death 25
Lameness 19
Increased sexual interest 12
Pneumonia 12
No sign 11
Death by euthanasia 11
Unclassifiable adverse event 11
Sexual disorder NOS (see 'Reproductive' for named sexual disorders) 10
Bloated 9
Rectal prolapse 8

Outcome Breakdown

Outcome Unknown
200 (69.0%)
Died
36 (12.4%)
Recovered/Normal
33 (11.4%)
Euthanized
12 (4.1%)
Recovered with Sequela
7 (2.4%)
Ongoing
2 (0.7%)

Melengestrol Acetate Adverse Event Insights

279 reports name Melengestrol Acetate; 46 recorded a death outcome (16.5% of reported events, not a population-level mortality rate). Active ingredient: Melengestrol Acetate. Administration routes: Oral, Unknown.

By species: Cattle (256 reports), Unknown (22 reports), Human (1 reports). By breed: Mixed (Cattle) (121), Cattle (other) (46), Cattle (unknown) (42).

Leading clinical signs: INEFFECTIVE, ESTRUS SUPPRESSIO (110), Lack of efficacy - NOS (79), Death (25), Lameness (19). Outcome, 290 coded reports: Outcome Unknown leads at 69.0%.

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.