Fenbendazole

• When using this product: Safe for use in puppies 6 weeks or older and adult dogs, including pregnant bitches. Do not deworm a dog or puppy that is sick.

Dosage: The daily dose is 50 mg/kg (22.7 mg/lb) of body weight.

Not for use in humans

1. 1Fatigue1618%
2. 2Diarrhoea1315%
3. 3Off Label Use1213%
4. 4Asthenia89.0%
5. 5Headache89.0%
6. 6Dyspnoea77.9%
7. 7Hot Flush77.9%
8. 8Nausea77.9%
9. 9Drug Effective For Unapproved Indication66.7%
10. 10Electrocardiogram Qt Prolonged66.7%
11. 11Insomnia66.7%
12. 12Tachyarrhythmia66.7%
13. 13Torsade De Pointes66.7%
14. 14Abdominal Discomfort55.6%
15. 15Accidental Exposure To Product55.6%

Recent PubMed references pinned to Fenbendazole as a MeSH major topic. Citations link to pubmed.ncbi.nlm.nih.gov.

• Computational insights into fenbendazole encapsulation by Cucurbit[n]urils (n = 7, 8): Implications for drug delivery and nanocarrier design through integrated structural, electronic, thermodynamic, and spectroscopic investigations.
  Journal of molecular graphics & modelling · 2026 · Alomari MI, Ababneh TS, Dawoud JN, et al.
  PMID 42013618DOI 10.1016/j.jmgm.2026.109410
• Pharmacokinetics of fenbendazole and its bioactive metabolite oxfendazole in northern bobwhite administered an anthelmintic feed.
  International journal for parasitology. Drugs and drug resistance · 2026 · Suber HN, Patel D, Arlowe TB, et al.
  PMID 41931961DOI 10.1016/j.ijpddr.2026.100640
• Thermal and Kinetic Analysis of Benzimidazole Derivatives: Fenbendazole, Mebendazole, and Flubendazole.
  Molecules (Basel, Switzerland) · 2026 · Ledeți A, Pârvănescu RD, Ridichie A, et al.
  PMID 41900104DOI 10.3390/molecules31061005
• Treatment efficacy of pyrantel, fenbendazole and macrocyclic lactones in equine strongyles in Germany using FECRT and the model eggCounts.
  Journal of equine veterinary science · 2025 · Döberl J, Li Z, Furrer R, et al.
  PMID 41177198DOI 10.1016/j.jevs.2025.105715
• [Cholestasis following use of fenbendazole as alternative cancer treatment].
  Tidsskrift for den Norske laegeforening : tidsskrift for praktisk medicin, ny raekke · 2025 · Skaara TR, Amdal CD, Jespersen H, et al.
  PMID 41097960DOI 10.4045/tidsskr.25.0229
• Fenbendazole-amino acid derivatives as novel anthelmintic candidates: Synthesis, activity against Haemonchus contortus, and in silico profiling.
  European journal of medicinal chemistry · 2026 · Colobbio M, Teixeira R, Duarte G, et al.
  PMID 41086532DOI 10.1016/j.ejmech.2025.118247
• ANTHELMINTIC THERAPIES FOR PARAFILAROIDES DECORUS PNEUMONIA IN CALIFORNIA SEA LIONS (ZALOPHUS CALIFORNIANUS).
  Journal of zoo and wildlife medicine : official publication of the American Association of Zoo Veterinarians · 2025 · Kane LP, Field CL, Hortensius LM, et al.
  PMID 41065684DOI 10.1638/2024-0021
• Beyond fenbendazole: Molecular and integrated pathways for managing poultry ascarid resistance.
  Poultry science · 2025 · Rattanapitoon SK, Charoenphon N, Rattanapitoon NK, et al.
  PMID 41061416DOI 10.1016/j.psj.2025.105942

The 7 most recently updated of 7 ClinicalTrials.gov registrations naming Fenbendazole as an intervention. Registration is not evidence of efficacy or safety — reference crosswalk only.

• One and Two Doses of Oxfendazole Versus a Schedule of Two Doses of Triclabendazole in Chronic Fascioliasis
  Not yet recruiting · Phase 2 · Interventional · 336 enrolled · Universidad Peruana Cayetano Heredia
  NCT06367361updated 2026-06-03
• A Safety and Efficacy Study of Different Doses of Oxfendazole Compared to a Single Dose of Albendazole to Treat Trichuris Trichiura Infection in Adults
  Recruiting · Phase 2 · Interventional · 249 enrolled · Asociacion Benefica Prisma
  NCT04713787updated 2025-07-29
• Project Safe Guard-Trauma
  Recruiting · Interventional · 168 enrolled · University of Colorado, Denver
  NCT06876740updated 2025-05-20
• COVID-19 in Baselland: Validation of Simple and Accurate Tests for COVID-19 Detection, Monitoring and Tracing (ACCURATE-BL-COVID-19)
  Unknown · Observational · 1,600 enrolled · University Hospital, Basel, Switzerland
  NCT04625257updated 2024-02-23
• Distal vs. Forearm Radial Artery Access
  Completed · Interventional · 212 enrolled · An-Najah National University
  NCT04125992updated 2023-06-06
• Multiple Ascending Dose Study of Oxfendazole in Healthy Adult Volunteers
  Completed · Phase 1 · Interventional · 36 enrolled · National Institute of Allergy and Infectious Diseases (NIAID)
  NCT03035760updated 2019-12-17
• A Study to Investigate Whether the Immediate Use or Deferred Use of an Anti-viral Drug Lamivudine Will Help to Better Safe-guard the Delivery of Chemotherapy in Patients With Cancer Who Are Also Hepatitis B Carriers
  Completed · Interventional · 110 enrolled · Hospital Authority, Hong Kong
  NCT00516945updated 2013-09-05

Frequently asked questions

What is Fenbendazole used for?

According to FDA labeling, Fenbendazole carries indications including: When using this product: Safe for use in puppies 6 weeks or older and adult dogs, including pregnant bitches. Do not deworm a dog or puppy that is sick.. This is a reference summary of labeled uses, not medical advice or a treatment recommendation.

What class of drug is Fenbendazole?

Fenbendazole is classified as Benzimidazole derivatives, Decreased Cell Wall Integrity.

What are the brand names for Fenbendazole?

Fenbendazole is marketed under brand names including Defendazole, GiarcidiaZap-Wormer, Panacur, Primacur, Safe-Guard.