Felimazole® — veterinary medication

Overview

Source: Animal Drugs @ FDA

Proprietary name

Felimazole®

Active ingredient

Methimazole

Application type

NADA

Sponsor

Dechra Veterinary Products LLC

Applications on record

1

First published

July 14, 2026

Adverse event reports

Source: openFDA VeDDRA

1,179

Reports mentioning this ingredient

August 26, 1998 – March 26, 2026

536

Classified serious

per reporter assessment

152

Lack of expected efficacy

resistance signal

4

Human operator exposure

needle-stick or splash

Not a risk measure. Veterinary adverse event reports are influenced by how many animals are treated, reporting practice and product age. Reports do not establish that the product caused the event, and a single report can cover an entire herd or flock. Attribution here is by active ingredient because the source dataset redacts brand names.

Attributed by active ingredient “METHIMAZOLE”. Green Book ingredient names and VeDDRA ingredient names do not always agree exactly, so attribution is approximate and labelled as such.

Reported reactions

Source: openFDA VeDDRA

Clinical signs coded in the VICH VeDDRA four-level hierarchy, most frequent first.

Reaction terms reported for this ingredient, by report count.
Reaction (VeDDRA term)	Reports	Relative frequency
Vomiting	52
Anorexia	34
Weight loss	24
Lack of efficacy - NOS	23
Lethargy (see also Central nervous system depression in Neurological)	21
Depression	19
Elevated alanine aminotransferase (ALT)	15
Death by euthanasia	14
Death	13
Pruritus	12
Not eating	12
Decreased appetite	12
Anaemia NOS	9
Underdose	9
Elevated creatinine	8
Elevated blood urea nitrogen (BUN)	8
Behavioural disorder NOS	8
Diarrhoea	7
Vocalisation	7
Hiding	7

Species affected

Source: openFDA VeDDRA

Cat 1,148 Dog 3

Regulatory context

New Animal Drug Application (NADA). A pioneer approval evaluated for target animal safety, therapeutic effectiveness, manufacturing controls and — for food-producing species — human food safety including residue depletion.

Extra-label use in food-producing animals is governed by the Animal Medicinal Drug Use Clarification Act of 1994 (AMDUCA) and 21 CFR Part 530. It requires a valid veterinarian-client-patient relationship and is prohibited outright for certain drug classes. Withdrawal times are determined by FARAD, not by this index.

Sources for this page

Animal Drugs @ FDA	FDA CVM	Applications, sponsor, status, withdrawal
Animal & Veterinary Events	FDA CVM	VeDDRA adverse event aggregates by active ingredient