Drug profile

The FDA adverse-event record for Chlorpheniramine

191 FDA reports name Chlorpheniramine, a high-volume drug in the CVM extract. Species, reactions, and outcomes follow.

#550 of 2,679
by report volume (all drugs)
191
adverse-event reports
10.5%
death-coded share
Dog
most-reported species

Corpus placement

According to the FDA Center for Veterinary Medicine openFDA adverse-event extract, Chlorpheniramine ranks #548 of 2679 by total reports (191) and #526 of 1130 by death-coded share (10.5%). 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)
#548
This drug, reports of 2679
#526
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. Chlorpheniramine has 191 reports now versus 187 in that prior snapshot: 4 more (2.1%).

Report change
+4
Death-coded reports
+0
Death-coded share
−0.2 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 Chlorpheniramine changes

Signature read: 191 reports place Chlorpheniramine in the upper third of FDA AER volume (#550 of 2,679).

Important: Adverse event reports do not establish that a drug caused or contributed to the event. Consult your veterinarian before making treatment decisions.
191
Total Reports
20
Deaths Reported
10.5%
Death-coded share of reports

Active Ingredients

Chlorpheniramine

Administration Routes

OralUnknownTransdermalTopicalSubcutaneous

Species Affected

Dog 132
Cat 59

Most Affected Breeds

Domestic Shorthair 45
Chihuahua 12
Maltese 12
Retriever - Labrador 9
Terrier - Yorkshire 7
Retriever - Golden 6
Shepherd Dog - German 6
Boxer (German Boxer) 5
Domestic Longhair 5
Lhasa Apso 4

Most Reported Reactions

Vomiting 29
Lethargy (see also Central nervous system depression in 'Neurological') 23
Other abnormal test result NOS 18
Diarrhoea 17
Anaemia NOS 15
Emesis 14
Weight loss 13
Decreased appetite 11
Lack of efficacy - NOS 11
Anorexia 11
Dehydration 10
Death by euthanasia 10

Outcome Breakdown

Ongoing
82 (42.9%)
Recovered/Normal
61 (31.9%)
Outcome Unknown
28 (14.7%)
Died
10 (5.2%)
Euthanized
10 (5.2%)

Chlorpheniramine: 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 Chlorpheniramine, both floored at ≥50 reports so the neighborhoods stay in the advertised mass.

What to do with this drug

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

openFDA Animal & Veterinary Adverse Events (FDA CVM) for Chlorpheniramine (#550 of 2,679 by report volume); death-coded 10.5%. PlainBreed drug row · report volume stamp 191 · vintage 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 →