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Fenbendazole and intestinal worms: what the evidence says

Small or mixed human studies suggest fenbendazole can clear roundworm and reduce hookworm and whipworm in people, based on 1970s trials of a form that was never approved for human use.

3/5 Limited

Some human evidence: small trials, trials on a related outcome, or population studies that disagree. How we score

Before it became an animal product, fenbendazole was tested in people under the code Hoe 881. A 1976 trial found single doses of 1 to 1.5 g effective against roundworm, with substantial falls in hookworm egg counts and good results against whipworm at the higher dose.

In the same report's comparison with pyrantel and placebo, it worked as well as pyrantel against hookworm and roundworm and better against whipworm. The abstract does not give patient numbers.

Trials from Mexico (1977) and on pinworm (1980) have no abstract in PubMed, so we have not counted them. A 1982 German case report describes successful treatment of a larval roundworm infection.

Human medicines for the same worms, such as albendazole, mebendazole and pyrantel, are prescribed today. Fenbendazole products on sale are labeled for animals.

The evidence ladder higher rungs count for more
  1. Meta-analyses of trialspooled randomized trials0
  2. Human studiestrials and population studies1
  3. Case reportssingle people1
  4. Animal studiesmostly rodents2
  5. Lab studiescells, test tubes3

The studies in people, read one by one

ResultTypeWhat they didWhat they found
PositiveClinical trial, 1976Single-dose trials in people, including a comparison with pyrantel and placebo
Measured: Worm clearance and egg counts
1 to 1.5 g was effective against roundworm and gave substantial egg-count reductions for hookworm; equal to pyrantel against hookworm and roundworm and better against whipworm. PubMed 779682
PositiveCase report, 1982
1 people
Case report, visceral larva migrans (larval roundworm infection)
Measured: Clinical response
The authors describe this first use in a human as highly effective against the infection. PubMed 7095820

Where the sources agree, and where they don’t

2 of 4 kinds of source point toward a benefit, 0 toward no effect or harm, 0 are mixed, and 2 have no data yet. Agreement between independent kinds of evidence matters more than the number of papers in any one of them.

Kind of sourcePoints toDetail
Human trials (1970s)Positivesingle doses cleared roundworm
Case reportPositive1982 larval roundworm infection
Registered trialsNo datanone for fenbendazole; sister drug oxfendazole is in worm trials
Public reportsNo datanot collected

What people report

None of the 40 public reports we read so far were about this condition. See all reports on the Fenbendazole page.

Every other paper we found

PubMed returned 11 papers for this search on 2026-10-28. We read the human studies above ourselves. The rest are sorted by type automatically from PubMed's labels, which are sometimes wrong.

Animal studies 2
  1. Efficacy of maslinic acid and fenbendazole on muscle larvae of Trichinella zimbabwensis in laboratory rats. J Helminthol, 2016
  2. Anthelmintic efficacy against tissue-arrested larvae of Ancylostoma caninum in murine hosts. J Parasitol, 1998
Lab studies 3
  1. Discovery of genomic intervals that underlie nematode responses to benzimidazoles. PLoS Negl Trop Dis, 2018
  2. Unexpected antitumorigenic effect of fenbendazole when combined with supplementary vitamins. J Am Assoc Lab Anim Sci, 2008
  3. [Therapeutic effectiveness of fenbendazole (HOE-881) in helminthiasis transmited by the soil in the state of Chiapas, Mexico]. Salud Publica Mex, 1977
Reviews 2
  1. Immunomodulatory effect of various anti-parasitics: a review. Parasitology, 2006
  2. Chemotherapy for larval echinococcosis in animals and humans: report of a workshop. Z Parasitenkd, 1982
Other papers, not yet read by us 2
  1. [Visceral larva migrans infection caused by Toxocara with bilateral exudative pleurisy]. Internist (Berl), 1986
  2. Fenbendazole (Hoe 881) in enterobiasis. Trans R Soc Trop Med Hyg, 1980

Other conditions Fenbendazole has been studied for

Checked against PubMed on 2026-10-28. Everything we know about Fenbendazole