Reaction profile
The FDA adverse-event record for lack of efficacy (flea)
8,320 FDA adverse-event reports reference lack of efficacy (flea) (VeDDRA 2649). See the species, breeds, and drugs most associated with it below.
- 8,320
- reports citing this reaction
- 0.2%
- death-coded share
- Dog
- most-affected species
- Nitenpyram
- most-associated drug
Species Most Affected
Breeds Most Affected
Associated Drugs
Lack of efficacy (flea) Reaction Insights
8,320 reports name Lack of efficacy (flea); 13 recorded a death outcome (0.2% of reported events, not a population-level mortality rate). VeDDRA code: 2649.
By species: Dog (7,217 reports), Cat (1,095 reports), Unknown (5 reports). By breed: Dog (unknown) (1,023), Crossbred Canine/dog (787), Chihuahua (630).
Most co-reported drugs: Nitenpyram (1,803 reports), Milbemycin Oxime + Spinosad (1,591 reports), Fluralaner Chew Tablets (1,451 reports), Spinosad (1,081 reports).
Read these counts as reporting volume, not risk: per our methodology, co-reporting reflects temporal association captured in voluntary submissions, not proof that a drug caused this reaction. A widely-prescribed drug will rack up more raw co-reports at an identical true rate than a rarely-used one, so compare within similar-exposure products.
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.