Drug profile

The FDA adverse-event record for Melarsomine Dihydrochloride

9,461 adverse-event reports submitted to the FDA Center for Veterinary Medicine reference Melarsomine Dihydrochloride. See the species affected, top reactions, and outcomes below.

9,461
adverse-event reports
4.0%
death-coded share
Dog
most-reported species
2,244
Lack of efficacy (endoparasite) - heartworm - 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.
9,461
Total Reports
375
Deaths Reported
4.0%
Death Rate

Active Ingredients

Melarsomine Dihydrochloride

Administration Routes

IntramuscularUnknownSubcutaneousParenteralOralOphthalmicIntravenousTopicalOtherIntradermal

Species Affected

Dog 9,221
Unknown 196
Human 40
Cat 4

Most Affected Breeds

Retriever - Labrador 1,348
Crossbred Canine/dog 1,133
Shepherd Dog - German 577
Dog (unknown) 462
Terrier - Bull - American Pit 434
Beagle 410
Chihuahua 375
Boxer (German Boxer) 300
Pit Bull 285
Unknown 245

Most Reported Reactions

Lack of efficacy (endoparasite) - heartworm 2,244
INEFFECTIVE, HEARTWORM ADULTS 1,087
Vomiting 1,067
Injection site swelling 849
Lethargy (see also Central nervous system depression in 'Neurological') 524
Injection site pain 511
Injection site lump 501
Diarrhoea 493
Pain NOS 480
Panting 414
Elevated alanine aminotransferase (ALT) 349
Anorexia 313

Outcome Breakdown

Ongoing
4,207 (55.0%)
Outcome Unknown
1,957 (25.6%)
Recovered/Normal
874 (11.4%)
Died
281 (3.7%)
Recovered with Sequela
234 (3.1%)
Euthanized
95 (1.2%)

Melarsomine Dihydrochloride Adverse Event Insights

9,461 reports name Melarsomine Dihydrochloride; 375 recorded a death outcome (4.0% of reported events, not a population-level mortality rate). Active ingredient: Melarsomine Dihydrochloride. Administration routes: Intramuscular, Unknown, Subcutaneous, Parenteral.

By species: Dog (9,221 reports), Unknown (196 reports), Human (40 reports). By breed: Retriever - Labrador (1,348), Crossbred Canine/dog (1,133), Shepherd Dog - German (577).

Leading clinical signs: Lack of efficacy (endoparasite) - heartworm (2,244), INEFFECTIVE, HEARTWORM ADULTS (1,087), Vomiting (1,067), Injection site swelling (849). Outcome, 7,648 coded reports: Ongoing leads at 55.0%.

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.