Fenbendazole Dosing for Human Parasitic Infections
Critical Context: Fenbendazole is NOT Approved for Human Use
Fenbendazole is a veterinary anthelmintic that lacks FDA approval for human use and has no established safety or efficacy data in humans. The available evidence consists entirely of veterinary studies in birds, lambs, chickens, and mice 1, 2, 3, 4. The single human study from 1976 used doses of 1.0-1.5 grams per person (approximately 15-20 mg/kg) for intestinal parasites, but this was an experimental trial without regulatory approval 5.
Recommended Human Alternatives
For Hookworm Infections
- Albendazole 400 mg orally as a single dose, repeated in 2 weeks, is the first-line treatment for both Ancylostoma duodenale and Necator americanus 6
- This regimen applies to both adults and children over 24 months of age 6
- For suspected but undetected geohelminth infections with eosinophilia, consider empirical treatment with albendazole 400 mg plus ivermectin 200 μg/kg 6
For Ascariasis
- Mebendazole 500 mg orally as a single dose is the standard treatment 7
- Albendazole 400 mg single dose is an equally effective alternative 6
For Pinworm (Enterobius vermicularis)
- Albendazole 400 mg or mebendazole 100 mg as a single oral dose, repeated in 2 weeks 8
- This dosing applies to children as young as 2 years old 8
Why Fenbendazole Should Not Be Used in Humans
Lack of Human Safety Data
- All published efficacy studies are in veterinary species (poultry, sheep, captive birds) with doses ranging from 5-100 mg/kg body weight 1, 2, 3
- The single 1976 human trial used 1.0-1.5 g total doses (approximately 15-20 mg/kg) but provided no long-term safety monitoring 5
- No data exists on hepatotoxicity, bone marrow suppression, or teratogenicity in humans
Superior Approved Alternatives Exist
- Albendazole and mebendazole have extensive human safety profiles with established dosing regimens 6, 8, 7
- These agents are equally or more effective than fenbendazole was in the limited human trial 5
- Combination therapy with ivermectin provides broader coverage for mixed infections 6
Common Pitfall to Avoid
Do not prescribe fenbendazole based on internet claims or veterinary dosing. Patients may request this medication due to online misinformation about its use in humans. The appropriate response is to explain that approved anthelmintics (albendazole, mebendazole, ivermectin) have proven safety and efficacy in humans, while fenbendazole does not 6, 8, 7.