Drug profile

The FDA adverse-event record for Cloxacillin Benzathine

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

133
adverse-event reports
57.1%
death-coded share
Cattle
most-reported species
74
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.
133
Total Reports
76
Deaths Reported
57.1%
Death Rate

Active Ingredients

Cloxacillin Benzathine

Administration Routes

IntramammaryUnknown

Species Affected

Cattle 105
Unknown 28

Most Affected Breeds

Holstein-Friesian also known as Holstein 56
Unknown 28
Cattle (other) 26
Cattle (unknown) 18
Jersey 3
Crossbred Bovine/Cattle 1
Brown Swiss 1

Most Reported Reactions

Death 74
Lack of efficacy (bacteria) - NOS 36
Acute mastitis 21
Mastitis NOS 18
Residues in milk 16
Abortion 12
CULTURE/TITER DATA ABNORMAL 8
Malaise 6
Containers, Damaged 6
Necropsy performed 6
Recumbency 5
Underfilling, Package 4

Outcome Breakdown

Died
74 (56.9%)
Outcome Unknown
27 (20.8%)
Recovered/Normal
24 (18.5%)
Euthanized
4 (3.1%)
Ongoing
1 (0.8%)

Cloxacillin Benzathine Adverse Event Insights

133 reports name Cloxacillin Benzathine; 76 recorded a death outcome (57.1% of reported events, not a population-level mortality rate). Active ingredient: Cloxacillin Benzathine. Administration routes: Intramammary, Unknown.

By species: Cattle (105 reports), Unknown (28 reports). By breed: Holstein-Friesian also known as Holstein (56), Unknown (28), Cattle (other) (26).

Leading clinical signs: Death (74), Lack of efficacy (bacteria) - NOS (36), Acute mastitis (21), Mastitis NOS (18). Outcome, 130 coded reports: Died leads at 56.9%.

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.