Active ingredient · pooled across combinations
Thiabendazole: adverse event reports, pooled
4 ingredient sets in reports · 22 FDA-approved applications in the Green Book
Thiabendazole appears, alone or combined with other ingredients, in 2,045 reports in FDA's animal adverse event database (January 1987 to March 2026). The figures here pool all 4 ingredient sets that include it.
The Green Book lists 22 FDA-approved applications containing it. openFDA masks brand and manufacturer names in adverse event records, so the reports counted here cannot be attributed to a particular brand.
183 reports arrived in the 12 months to March 2026, up 34% from 137 in the 12 months before. FDA posts reports quarterly with a delay of three to six months, so the newest months are incomplete and usually grow in later releases. That is about 52 reports a year over its reporting history and 0.2% of all reports.
Pooled across every set, the terms listed most often are lethargy (11.4%), vomiting (8.4%) and accidental exposure (8.3%). Many drugs combine several ingredients, and many reports list several drugs, so a term on this page may relate to any of them or to none.
Of reports that state seriousness, 36.4% were classed as serious (38.6% across the whole database); 5.7% record a death or euthanasia (6.4% overall). Ingredients used in older or sicker animals, or in anaesthesia and cancer care, carry higher shares for that reason alone.
Ingredient sets that include thiabendazole
| Active ingredients recorded for the drug | Reports | Share of this page's reports | Latest 12 months |
|---|---|---|---|
| Dexamethasone + Neomycin Sulfate + Thiabendazole | 1,088 | 53.2% | 162 |
| Dexamethasone + Thiabendazole | 900 | 44% | 20 |
| Thiabendazole | 56 | 2.7% | 0 |
| Dexamethasone + Ivermectin + Neomycin Sulfate + Thiabendazole | 1 | 0% | 1 |
Ordered by report count. FDA states that these data "cannot be used to estimate the risk associated with the product or compare one drug or device product with another"; counts follow sales volume and years on the market. A report can list more than one set, so shares can add to more than 100%.
Signs listed in reports, pooled
share of thiabendazole reports listing the termall reports in the database
- Lethargy[unusually tired or inactive]11.4%234
- Vomiting8.4%171
- Accidental exposure[exposure that was not intended]8.3%169
- Eye irritation6.7%136
- Unclassifiable adverse event[event that fits no dictionary term]5.6%114
- Anorexia[not eating]5.5%112
- Ataxia[unsteady, uncoordinated movement]4.9%100
- Deafness4.6%95
- Elevated alanine aminotransferase (ALT)[a liver enzyme above the normal range]4.4%91
- Lack of efficacy - NOS[the product did not have the expected effect]4.4%90
- Dispenser, Abnormal[a product quality report, not a sign in an animal]4.2%85
- Not eating3.9%79
- Pinnal erythema3.3%68
- Other abnormal test result NOS[abnormal laboratory result, type not specified]3.2%66
- Eye pain3.2%65
- Behavioural disorder NOS[behaviour change, type not specified]3.1%64
- Weight loss3%62
- Diarrhoea[diarrhea]3%61
- Vials, Damaged[a product quality report, not a sign in an animal]2.9%60
- Containers, Abnormal[a product quality report, not a sign in an animal]2.8%58
- Death by euthanasia[the animal was euthanized]2.8%58
- Death2.6%53
- Decreased appetite2.5%52
- Elevated total bilirubin[bilirubin above the normal range]2.4%49
- Fever2.3%47
- Depression[dull, quiet or withdrawn]2.2%46
- Vocalisation[crying out or unusual noise]2.1%43
- Emesis[vomiting]2.1%42
- Hyperglycaemia[high blood sugar]2%41
- Pruritus[itching]2%41
Pooled across every ingredient set and every report that names the ingredient. One report can list several terms and several drugs; a term here may relate to any of them or to none.
Monthly reports by species, five years
By month of receipt; each panel has its own scale. The newest months are incomplete because FDA posts reports with a delay of three to six months.
Outcomes, report types and ages
Outcome recorded in the report
What kind of report it was
Age of the animal
Coloured bar: reports naming thiabendazole. Grey bar: all 1,357,245 reports. Outcomes are as stated by the reporter; FDA has not necessarily determined whether any product played a part.
In context
| Measure | Thiabendazole | All reports |
|---|---|---|
| Reports | 2,045 | 1,357,245 |
| Latest 12 months against the 12 before | +34% | -5% |
| Classed serious, of reports stating it | 36.4% | 38.6% |
| Death or euthanasia recorded, per 1,000 reports | 56.7 | 63.8 |
| Filed as lack of expected effectiveness (wholly or partly) | 5.8% | 23% |
Shares of reports, not of animals treated: how many animals receive the ingredient is not public. Ingredients used in anaesthesia, cancer care or in old animals carry more serious outcomes in their reports for that reason alone.
FDA-approved products containing thiabendazole (Green Book)
Reference information, not report statistics. openFDA masks brand and manufacturer names in adverse event records, so the reports counted here cannot be attributed to a particular brand. The list below is the FDA Green Book as of 1 Oct 2026; nothing on this page says which of these products, if any, a report concerned.
| Trade name | Active ingredients | Sponsor | Approved for | Application |
|---|---|---|---|---|
| Tresaderm Dermatologic Solution | Dexamethasone, Neomycin Sulfate, Thiabendazole | Boehringer Ingelheim Animal Health USA, Inc. | Dogs, Cats | NADA 042-633 |
| Equivet-14; Equizole-B | Thiabendazole, Trichlorfon | Farnam Companies, Inc. | Horses | NADA 091-067 |
| Thiabendazole, Dexamethasone, Neomycin Sulfate Solution | Dexamethasone, Neomycin Sulfate, Thiabendazole | Dechra Veterinary Products LLC | Dogs, Cats | ANADA 200-565 |
| Thibenzole Sheep & Goat Wormerapproval voluntarily withdrawn | Thiabendazole | Boehringer Ingelheim Animal Health USA Inc. | Sheep, Goats | NADA 013-022 |
| Equizole Horse Wormerapproval voluntarily withdrawn | Thiabendazole | Boehringer Ingelheim Animal Health USA Inc. | Horses | NADA 013-407 |
| Thibenzole 20% Swine Premixapproval voluntarily withdrawn | Thiabendazole | Boehringer Ingelheim Animal Health USA Inc. | Swine | NADA 013-954 |
| Omnizoleapproval voluntarily withdrawn | Thiabendazole | Boehringer Ingelheim Animal Health USA Inc. | Cattle, Sheep, Goats | NADA 014-350 |
| TBZ Cattle Wormer (Drench)approval voluntarily withdrawn | Thiabendazole | Boehringer Ingelheim Animal Health USA Inc. | Cattle | NADA 015-123 |
| TBZ 200 Medicated Feed Premixapproval voluntarily withdrawn | Thiabendazole | Boehringer Ingelheim Animal Health USA Inc. | Cattle, Swine, Sheep, Goats | NADA 015-875 |
| Thibenzole (18 mg)approval voluntarily withdrawn | Thiabendazole | Boehringer Ingelheim Animal Health USA Inc. | Cattle | NADA 030-103 |
| E-Z-EX Wormer Pelletsapproval voluntarily withdrawn | Thiabendazole | ADM Animal Nutrition | Cattle, Sheep, Goats | NADA 030-578 |
| Equizoleapproval voluntarily withdrawn | Thiabendazole | Boehringer Ingelheim Animal Health USA Inc. | Horses, Cattle, Sheep, Goats | NADA 034-114 |
| Thibenzole Pig Wormerapproval voluntarily withdrawn | Thiabendazole | Boehringer Ingelheim Animal Health USA Inc. | Swine | NADA 035-631 |
| Equizole Aapproval voluntarily withdrawn | Piperazine Phosphate, Thiabendazole | Boehringer Ingelheim Animal Health USA Inc. | Horses | NADA 037-410 |
| Purina Horse Wormer Medicatedapproval voluntarily withdrawn | Thiabendazole | Virbac AH, Inc. | Horses | NADA 040-205 |
| E-Z-EX Wormer Mintrate Blockapproval voluntarily withdrawn | Thiabendazole | ADM Animal Nutrition | Cattle | NADA 042-910 |
| Thibenzole 300 Medicatedapproval voluntarily withdrawn | Thiabendazole | Boehringer Ingelheim Animal Health USA Inc. | Cattle | NADA 043-141 |
| Equizole Horse Wormer Pelletsapproval voluntarily withdrawn | Thiabendazole | Boehringer Ingelheim Animal Health USA Inc. | Horses | NADA 044-654 |
| Equizole A Liquidapproval voluntarily withdrawn | Piperazine Citrate, Thiabendazole | Boehringer Ingelheim Animal Health USA Inc. | Horses | NADA 047-333 |
| TBZ Wormer Paste 50%approval voluntarily withdrawn | Thiabendazole | Boehringer Ingelheim Animal Health USA Inc. | Cattle | NADA 048-487 |
| TBZ Wormer Paste 43%approval voluntarily withdrawn | Thiabendazole | Boehringer Ingelheim Animal Health USA Inc. | Cattle | NADA 049-461 |
| Equizole 50% Wormer Paste; Equizole 50% Wormer Paste For Horsesapproval voluntarily withdrawn | Thiabendazole | Boehringer Ingelheim Animal Health USA Inc. | Horses | NADA 098-689 |
Species are the major species the Green Book search lists for the application ("—" where it lists another species or none). Approval dates are not part of the Green Book listing files and are not shown. Pioneer applications (NADA) come first, then generics (ANADA).
Questions about thiabendazole reports
How many FDA adverse event reports mention thiabendazole?
2,045 reports through March 2026, 183 of them in the latest 12 months, counting thiabendazole alone and in combinations.
Which brands do these reports concern?
That cannot be known from the public data. openFDA masks brand and manufacturer names in adverse event records, so the reports counted here cannot be attributed to a particular brand. The Green Book reference list on this page names approved products containing thiabendazole without any counts.
In which combinations is thiabendazole reported?
Dexamethasone + Neomycin Sulfate + Thiabendazole (53.2% of these reports), Dexamethasone + Thiabendazole (44% of these reports), Thiabendazole (2.7% of these reports) and Dexamethasone + Ivermectin + Neomycin Sulfate + Thiabendazole (0% of these reports).
What reactions are reported for thiabendazole?
lethargy (11.4%), vomiting (8.4%), accidental exposure (8.3%), eye irritation (6.7%) and unclassifiable adverse event (5.6%). Shares are of reports naming the ingredient; one report can list several terms.
Which animals are these reports about?
cat (38.5%), dog (32.4%) and human exposure (9.1%).
Does a high count mean thiabendazole is a problem ingredient?
A count cannot show that. FDA states that "there is no certainty that the reported drug or device caused the adverse event" and that the event "may have been related to an underlying disease, other drugs used at the same time or other non-drug related sources." Widely used ingredients collect more reports because more animals receive them.
How do I report a problem?
Call the drug company using the number on the label, or send Form FDA 1932a to FDA. See the guide on how to report.
Where this comes from. Counts are built from the openFDA Animal & Veterinary adverse event bulk files released 28 Sep 2026, which hold reports FDA's Center for Veterinary Medicine received through 31 Mar 2026. openFDA masks brand and manufacturer names in these files, so drugs are counted by the active ingredients each record discloses and no figure is attributed to a brand, application or company. Ingredient names, and the separate reference lists of approved products, follow the FDA Green Book as of 1 Oct 2026. Ingredient names follow the Green Book; salts and forms are kept as FDA lists them. Drug entries are matched by the active ingredients their unmasked ingredient field discloses. No report text, lot numbers or reporter details are published. See the methodology and sources; FDA's record is authoritative, and corrections are handled within five working days.