Pet Drug Reports

Ingredients

Active ingredient · pooled across combinations

Thiabendazole: adverse event reports, pooled

4 ingredient sets in reports · 22 FDA-approved applications in the Green Book

2,045reports naming the ingredient, 1987–20260.2% of all reports · about 52 a year
183reports, 12 months to March 2026137 in the 12 months before
36.4%classed serious, as reportedall reports: 38.6%
38.5%of reports concern catsdog 32.4%

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 drugReportsShare of this page's reportsLatest 12 months
Dexamethasone + Neomycin Sulfate + Thiabendazole1,08853.2%162
Dexamethasone + Thiabendazole90044%20
Thiabendazole562.7%0
Dexamethasone + Ivermectin + Neomycin Sulfate + Thiabendazole10%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

  1. Lethargy[unusually tired or inactive]11.4%234
  2. Vomiting8.4%171
  3. Accidental exposure[exposure that was not intended]8.3%169
  4. Unclassifiable adverse event[event that fits no dictionary term]5.6%114
  5. Anorexia[not eating]5.5%112
  6. Ataxia[unsteady, uncoordinated movement]4.9%100
  7. Deafness4.6%95
  8. Elevated alanine aminotransferase (ALT)[a liver enzyme above the normal range]4.4%91
  9. Lack of efficacy - NOS[the product did not have the expected effect]4.4%90
  10. Dispenser, Abnormal[a product quality report, not a sign in an animal]4.2%85
  11. Other abnormal test result NOS[abnormal laboratory result, type not specified]3.2%66
  12. Eye pain3.2%65
  13. Behavioural disorder NOS[behaviour change, type not specified]3.1%64
  14. Diarrhoea[diarrhea]3%61
  15. Vials, Damaged[a product quality report, not a sign in an animal]2.9%60
  16. Containers, Abnormal[a product quality report, not a sign in an animal]2.8%58
  17. Death by euthanasia[the animal was euthanized]2.8%58
  18. Death2.6%53
  19. Elevated total bilirubin[bilirubin above the normal range]2.4%49
  20. Fever2.3%47
  21. Depression[dull, quiet or withdrawn]2.2%46
  22. Vocalisation[crying out or unusual noise]2.1%43
  23. Emesis[vomiting]2.1%42
  24. Hyperglycaemia[high blood sugar]2%41
  25. 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

Dog101 · peak 6
Apr 2021: 1May 2021: 1Jun 2021: 2Jul 2021: 3Aug 2021: 2Sep 2021: 2Nov 2021: 5Jan 2022: 2Mar 2022: 1Apr 2022: 6May 2022: 2Sep 2022: 3Oct 2022: 3Nov 2022: 3Dec 2022: 1Jan 2023: 1Feb 2023: 1Mar 2023: 1Apr 2023: 1Aug 2023: 4Sep 2023: 1Jan 2024: 2Feb 2024: 1Mar 2024: 1Apr 2024: 2May 2024: 3Jun 2024: 2Jul 2024: 1Aug 2024: 1Sep 2024: 5Oct 2024: 1Nov 2024: 2Jan 2025: 1Feb 2025: 1Apr 2025: 2May 2025: 2Jun 2025: 5Jul 2025: 1Aug 2025: 1Oct 2025: 4Nov 2025: 6Dec 2025: 5Jan 2026: 3Feb 2026: 2Mar 2026: 12022202320242025
Cat384 · peak 16
Apr 2021: 4May 2021: 3Jun 2021: 4Jul 2021: 7Aug 2021: 2Sep 2021: 1Oct 2021: 3Nov 2021: 5Dec 2021: 3Jan 2022: 1Feb 2022: 8Mar 2022: 7Apr 2022: 5May 2022: 4Jun 2022: 5Jul 2022: 9Aug 2022: 4Sep 2022: 4Oct 2022: 7Nov 2022: 2Dec 2022: 3Jan 2023: 4Feb 2023: 8Mar 2023: 4Apr 2023: 9May 2023: 6Jun 2023: 2Jul 2023: 1Aug 2023: 4Sep 2023: 5Oct 2023: 1Nov 2023: 1Dec 2023: 4Jan 2024: 6Feb 2024: 8Mar 2024: 5Apr 2024: 3May 2024: 7Jun 2024: 4Jul 2024: 6Aug 2024: 16Sep 2024: 11Oct 2024: 12Nov 2024: 8Dec 2024: 5Jan 2025: 6Feb 2025: 10Mar 2025: 8Apr 2025: 8May 2025: 16Jun 2025: 10Jul 2025: 3Aug 2025: 6Sep 2025: 9Oct 2025: 14Nov 2025: 16Dec 2025: 15Jan 2026: 13Feb 2026: 14Mar 2026: 52022202320242025
Horse0 · peak 1
2022202320242025
Other118 · peak 7
Apr 2021: 2Jun 2021: 3Aug 2021: 3Sep 2021: 4Oct 2021: 2Nov 2021: 1Dec 2021: 2Jan 2022: 2Feb 2022: 4Mar 2022: 1Apr 2022: 1May 2022: 1Jun 2022: 3Jul 2022: 1Aug 2022: 4Sep 2022: 4Oct 2022: 1Nov 2022: 4Dec 2022: 2Jan 2023: 3Feb 2023: 3Mar 2023: 4Apr 2023: 2May 2023: 4Jun 2023: 1Aug 2023: 1Sep 2023: 2Oct 2023: 1Dec 2023: 4Jan 2024: 1Feb 2024: 1Mar 2024: 2Apr 2024: 2May 2024: 3Jun 2024: 2Jul 2024: 2Aug 2024: 2Sep 2024: 3Nov 2024: 1Jan 2025: 2Feb 2025: 4Mar 2025: 1May 2025: 1Jul 2025: 2Aug 2025: 2Sep 2025: 4Oct 2025: 2Nov 2025: 2Dec 2025: 2Jan 2026: 72022202320242025

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.

0861711987: 319871989: 31990: 11991: 119911992: 11996: 51997: 119971998: 21999: 102000: 620002001: 122002: 172003: 4220032004: 622005: 592006: 7920062007: 1342008: 742009: 7220092010: 862011: 752012: 4320122013: 382014: 272015: 3120152016: 542017: 822018: 12220182019: 1332020: 1262021: 10620212022: 1082023: 832024: 13120242025: 1712026: 45

Outcomes, report types and ages

Outcome recorded in the report

Recovered/Normal11.9%244
Recovered with Sequela0.4%8
Ongoing12%246
Died3.1%63
Euthanized2.6%53
Outcome Unknown26.8%549

What kind of report it was

Safety issue74.5%1,523
Lack of expected effectiveness2.1%43
Both safety and lack of expected effectiveness3.7%76
Manufacturing or product defect19.6%400
Other0.1%3

Species

Cat38.5%787
Dog32.4%662
Human exposure9.1%186
Ferret0.2%5
Cattle0.2%4
Sheep0.1%2

Age of the animal

Under 1 year9.4%193
1 to 3 years13.7%280
4 to 7 years15.6%318
8 to 11 years15.7%321
12 years and over15.9%326
Age not given29.7%607

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

MeasureThiabendazoleAll reports
Reports2,0451,357,245
Latest 12 months against the 12 before+34%-5%
Classed serious, of reports stating it36.4%38.6%
Death or euthanasia recorded, per 1,000 reports56.763.8
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 nameActive ingredientsSponsorApproved forApplication
Tresaderm Dermatologic SolutionDexamethasone, Neomycin Sulfate, ThiabendazoleBoehringer Ingelheim Animal Health USA, Inc.Dogs, CatsNADA 042-633
Equivet-14; Equizole-BThiabendazole, TrichlorfonFarnam Companies, Inc.HorsesNADA 091-067
Thiabendazole, Dexamethasone, Neomycin Sulfate SolutionDexamethasone, Neomycin Sulfate, ThiabendazoleDechra Veterinary Products LLCDogs, CatsANADA 200-565
Thibenzole Sheep & Goat Wormerapproval voluntarily withdrawnThiabendazoleBoehringer Ingelheim Animal Health USA Inc.Sheep, GoatsNADA 013-022
Equizole Horse Wormerapproval voluntarily withdrawnThiabendazoleBoehringer Ingelheim Animal Health USA Inc.HorsesNADA 013-407
Thibenzole 20% Swine Premixapproval voluntarily withdrawnThiabendazoleBoehringer Ingelheim Animal Health USA Inc.SwineNADA 013-954
Omnizoleapproval voluntarily withdrawnThiabendazoleBoehringer Ingelheim Animal Health USA Inc.Cattle, Sheep, GoatsNADA 014-350
TBZ Cattle Wormer (Drench)approval voluntarily withdrawnThiabendazoleBoehringer Ingelheim Animal Health USA Inc.CattleNADA 015-123
TBZ 200 Medicated Feed Premixapproval voluntarily withdrawnThiabendazoleBoehringer Ingelheim Animal Health USA Inc.Cattle, Swine, Sheep, GoatsNADA 015-875
Thibenzole (18 mg)approval voluntarily withdrawnThiabendazoleBoehringer Ingelheim Animal Health USA Inc.CattleNADA 030-103
E-Z-EX Wormer Pelletsapproval voluntarily withdrawnThiabendazoleADM Animal NutritionCattle, Sheep, GoatsNADA 030-578
Equizoleapproval voluntarily withdrawnThiabendazoleBoehringer Ingelheim Animal Health USA Inc.Horses, Cattle, Sheep, GoatsNADA 034-114
Thibenzole Pig Wormerapproval voluntarily withdrawnThiabendazoleBoehringer Ingelheim Animal Health USA Inc.SwineNADA 035-631
Equizole Aapproval voluntarily withdrawnPiperazine Phosphate, ThiabendazoleBoehringer Ingelheim Animal Health USA Inc.HorsesNADA 037-410
Purina Horse Wormer Medicatedapproval voluntarily withdrawnThiabendazoleVirbac AH, Inc.HorsesNADA 040-205
E-Z-EX Wormer Mintrate Blockapproval voluntarily withdrawnThiabendazoleADM Animal NutritionCattleNADA 042-910
Thibenzole 300 Medicatedapproval voluntarily withdrawnThiabendazoleBoehringer Ingelheim Animal Health USA Inc.CattleNADA 043-141
Equizole Horse Wormer Pelletsapproval voluntarily withdrawnThiabendazoleBoehringer Ingelheim Animal Health USA Inc.HorsesNADA 044-654
Equizole A Liquidapproval voluntarily withdrawnPiperazine Citrate, ThiabendazoleBoehringer Ingelheim Animal Health USA Inc.HorsesNADA 047-333
TBZ Wormer Paste 50%approval voluntarily withdrawnThiabendazoleBoehringer Ingelheim Animal Health USA Inc.CattleNADA 048-487
TBZ Wormer Paste 43%approval voluntarily withdrawnThiabendazoleBoehringer Ingelheim Animal Health USA Inc.CattleNADA 049-461
Equizole 50% Wormer Paste; Equizole 50% Wormer Paste For Horsesapproval voluntarily withdrawnThiabendazoleBoehringer Ingelheim Animal Health USA Inc.HorsesNADA 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.