Drug profile
The FDA adverse-event record for Diphenhydramine Hcl
2,111 FDA reports name Diphenhydramine Hcl, a high-volume drug in the CVM extract. Species, reactions, and outcomes follow.
- #108 of 2,679
- by report volume (all drugs)
- 2,111
- adverse-event reports
- 14.2%
- death-coded share
- Dog
- most-reported species
Corpus placement
According to the FDA Center for Veterinary Medicine openFDA adverse-event extract, Diphenhydramine Hcl ranks #108 of 2679 by total reports (2,111) and #391 of 1130 by death-coded share (14.2%). National dual: Milbemycin Oxime + Spinosad is #1 of 2679 drugs by total adverse-event reports (149,624) at death-coded-share rank 965 of 1130 drugs with at least 50 reports (2.3%); separately, Atlantic Salmon Transgenic Whole (Opafp-Ghc2 Rdna Construct Inserted Into The A-Locus In The Eo-1A Lineage) is #1 highest death-coded share at 97.8% (report rank #821).
- 149,624
- Milbemycin Oxime + Spinosad reports (#1)
- 97.8%
- Atlantic Salmon Transgenic Whole (Opafp-Ghc2 Rdna Construct Inserted Into The A-Locus In The Eo-1A Lineage) death share (#1)
- #108
- This drug, reports of 2679
- #391
- This drug, death share of 1130
Report volume reflects how common a breed or drug is and how often owners and vets file — not actual risk. Death-coded share ranks are limited to entries with enough reports to be meaningful. The two maps do not agree at #1.
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. Diphenhydramine Hcl has 2,111 reports now versus 2,110 in that prior snapshot: 1 more (0.0%).
- Report change
- +1
- 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 Diphenhydramine Hcl changesSignature read: death-coded report count at 300 is the most distinctive stamp on Diphenhydramine Hcl's FDA AER row.
Active Ingredients
Administration Routes
Species Affected
Most Affected Breeds
Most Reported Reactions
Outcome Breakdown
Diphenhydramine Hcl: high report volume in the FDA AER row
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.
High-volume nationwide drug peers
Two openFDA-derived peer sets for Diphenhydramine Hcl, both floored at ≥50 reports so the neighborhoods stay in the advertised mass.
Similar report volume
Nearest other drugs by FDA report count (2,111 here).
Similar death-coded share
Nearest other drugs by death-coded share (14.2% here), distinct from the volume row.
What to do with this drug
- Compare Diphenhydramine Hcl's report volume and death-coded share against similar drugs nationwide. See similar drugs
- Read how death-coded share differs from a mortality rate before drawing conclusions. Understanding adverse events
- Browse the full drug directory to compare report counts across products. All drugs
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 →