Reaction profile
The FDA adverse-event record for lack of efficacy (lice)
450 FDA reports name lack of efficacy (lice), a high-volume reaction in the CVM extract (VeDDRA 2651). Plate stamps and neighbourhood peers follow.
- #681 of 2,481
- by report volume (all reactions)
- 450
- reports citing this reaction
- 0.0%
- death-coded share
- Cattle
- most-affected species
Release-over-release change
What changed in the latest FDA data snapshot
PlainBreed reconstructed the prior snapshot from dated openFDA partitions through 2025 Q4, then compared it with the 2026-07-27 openFDA export. Lack of efficacy (lice) has 450 reports now versus 450 in that prior snapshot: 0 the same number of (0.0%).
- Report change
- +0
- Death-coded reports
- +0
- Death-coded share
- +0.0 pts
This compares reported-event counts in two source snapshots. It does not establish a change in real-world risk, product safety, or disease incidence.
Subscribe to Lack of efficacy (lice) changesFDA AER · VeDDRA plate
Code 2651 VOL-LOW
VOL-LOW · DEATH-RARE · MID-PACK · PHOTO-FINISH · SPECIES-CATTLE · DRUG-LEAD · DESK-WIDE · BOOK-FULL
- VOL-LOW 450 reports
- DEATH-RARE 0.0%
- MID-PACK #681/2481
- PHOTO-FINISH Eyelid oedema
- SPECIES-CATTLE Cattle · 445
- DRUG-LEAD Doramectin · 279
- DESK-WIDE 16 breeds
- BOOK-FULL 8/8 fields
Nearest volume peer: Eyelid oedema (±0 reports)
Upper-third report volume drives the scale stamps on this plate; death-coded share and co-report peers follow. Not a clinical diagnosis.
High-volume neighbourhood around Lack of efficacy
Upper-third volume poles plus nearest peers, not a full reaction corpus board reprint.
Lack of efficacy (lice): low death-coded share in the FDA AER plate
Signature read: Lack of efficacy (lice)'s 0.0% death-coded share is among the lowest in the openFDA reaction corpus. Report volume is upper-third scale: 450 named reports in the openFDA extract. Death-coded share is lower-third: 0 of 450 reports (0.0% of named reports). Nearest volume peer: Eyelid oedema (±0 reports). Lead species Cattle (445). Lead co-reported drug Doramectin (279).
Read these counts as reporting volume, not risk: per our methodology, Lead co-reported drug Doramectin appears in filings alongside this reaction; that is association, not causation. Browse the full reactions index or the about page for how PlainBreed frames FDA CVM extracts.
Species Most Affected
Breeds Most Affected
Associated Drugs
Nationwide reactions with similar profiles
Two openFDA-derived peer sets for Lack of efficacy (lice), both floored at ≥50 reports so the neighborhoods stay in the advertised mass (the volume chart above is the unfloored photo-finish strip).
Similar report volume
Nearest other reactions by FDA report count (450 here).
Similar death-coded share
Nearest other reactions by death-coded share (0.0% here), distinct from the volume row.
What to do with this reaction
- Compare Lack of efficacy's report profile against similar reactions nationwide. See similar reactions
- Read how death-coded share differs from a mortality rate before drawing conclusions. Understanding adverse events
- Browse the full reaction directory to compare report counts across reaction types. All reactions
A report does not prove a drug caused the reaction; consult a veterinarian before acting on this data.
Source: FDA Center for Veterinary Medicine openFDA Animal & Veterinary Adverse Events (CVM AER) · 2025
Informational only. FDA adverse-event reports are voluntary and do not prove causation; consult a veterinarian before acting on them. Verify with FDA CVM →