Drug profile

The FDA adverse-event record for Lomustine

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

30
adverse-event reports
33.3%
death-coded share
Dog
most-reported species
7
Decreased appetite - 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.
30
Total Reports
10
Deaths Reported
33.3%
Death Rate

Active Ingredients

Lomustine

Administration Routes

UnknownOralIntravenous

Species Affected

Dog 21
Cat 9

Most Affected Breeds

Domestic Shorthair 9
Retriever - Labrador 3
Mountain Dog - Bernese 2
Crossbred Canine/dog 2
Dog (unknown) 2
Chihuahua 2
Terrier - Fox (unspecified) 1
Bulldog - French 1
Pug 1
Portuguese Water Dog 1

Most Reported Reactions

Decreased appetite 7
Death by euthanasia 7
Lack of efficacy - NOS 6
Diarrhoea 6
Lethargy (see also Central nervous system depression in 'Neurological') 6
Behavioural disorder NOS 5
Anorexia 4
Weight loss 4
Elevated serum alkaline phosphatase (SAP) 4
Elevated blood urea nitrogen (BUN) 4
Elevated creatinine 4
Vomiting 3

Outcome Breakdown

Ongoing
10 (33.3%)
Euthanized
7 (23.3%)
Outcome Unknown
6 (20.0%)
Recovered/Normal
4 (13.3%)
Died
3 (10.0%)

Lomustine Adverse Event Insights

30 reports name Lomustine; 10 recorded a death outcome (33.3% of reported events, not a population-level mortality rate). Active ingredient: Lomustine. Administration routes: Unknown, Oral, Intravenous.

By species: Dog (21 reports), Cat (9 reports). By breed: Domestic Shorthair (9), Retriever - Labrador (3), Mountain Dog - Bernese (2).

Leading clinical signs: Decreased appetite (7), Death by euthanasia (7), Lack of efficacy - NOS (6), Diarrhoea (6). Outcome, 30 coded reports: Ongoing leads at 33.3%.

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.