Drug profile

The FDA adverse-event record for Monensin

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

261
adverse-event reports
51.7%
death-coded share
Cattle
most-reported species
124
Death - 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.
261
Total Reports
135
Deaths Reported
51.7%
Death Rate

Active Ingredients

Monensin

Administration Routes

OralUnknownOphthalmic

Species Affected

Cattle 189
Turkey 26
Chicken 14
Horse 10
Goat 7
Dog 4
Other 2
Sheep 2
Unknown 2
Other Birds 2

Most Affected Breeds

Crossbred Bovine/Cattle 76
Cattle (unknown) 38
Holstein-Friesian also known as Holstein 33
Turkey (unknown) 25
Unknown 17
Chicken (unknown) 14
Cattle (other) 9
Horse (unknown) 7
Aberdeen Angus 7
Jersey 6

Most Reported Reactions

Death 124
Anorexia 60
Diarrhoea 58
Lack of efficacy (protozoa) - Coccidia 50
Accidental exposure 43
Recumbency 29
Inappropriate preparation of medication 24
Bloody diarrhoea 19
Milk production decrease 17
Depression 12
Alteration of milk quality 11
PR-HEART, LESION(S) 11

Outcome Breakdown

Died
134 (78.8%)
Outcome Unknown
27 (15.9%)
Recovered/Normal
5 (2.9%)
Ongoing
2 (1.2%)
Euthanized
2 (1.2%)

Monensin Adverse Event Insights

261 reports name Monensin; 135 recorded a death outcome (51.7% of reported events, not a population-level mortality rate). Active ingredient: Monensin. Administration routes: Oral, Unknown, Ophthalmic.

By species: Cattle (189 reports), Turkey (26 reports), Chicken (14 reports). By breed: Crossbred Bovine/Cattle (76), Cattle (unknown) (38), Holstein-Friesian also known as Holstein (33).

Leading clinical signs: Death (124), Anorexia (60), Diarrhoea (58), Lack of efficacy (protozoa) - Coccidia (50). Outcome, 170 coded reports: Died leads at 78.8%.

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.