Flubendazole is an antiparasitic active ingredient used in veterinary medicine in livestock and pets against internal parasites (roundworms, tapeworms). It is not used against agricultural and household pests. It belongs to the chemical class of the benzimidazoles.

Common name:  FLUBENDAZOLE

Type: veterinary medecine
Chemical class: benzimidazole


Molecular structure of FLUBENDAZOLE 


Type of action: broad-spectrum nematicide and taenicide anthelmintic, endoparasiticide
Main veterinary parasites controlled: gastrointestinal and respiratory roundworms (= nematodes) and tapeworms

Efficacy against a specific parasite depends on the delivery form and on the dose administered.

Click here for general information on features and characteristics of PARASITICIDES.


Click here to view the article in this site with the most common dosing recommendations for flubendazole used in domestic animals.


Oral LD50, rat, acute*: >5000 mg/kg
Dermal LD50, rat, acute*: not found
* These values refer to the active ingredient. Toxicity has to be determined for each formulation as well. Formulations are usually significantly less toxic than the active ingredients.

MRL (maximum residue limit) established for either beef, mutton pork or chicken meat*:

  • CODEX: Yes
  • EU: Yes
  • USA: No
  • AUS: No

* This information is an indicator of the acceptance of an active ingredient by the most influential regulatory bodies for use on livestock.

Withholding periods for meat, milk, eggs, etc. depend on delivery form, dose and national regulations. Check the product label in your country.

Learn more about flubendazole safety (poisoning, intoxication, overdose, antidote, symptoms, etc.).

General safety information for antiparasitics is available in specific articles in this site (click to visit):


Never use agricultural or hygiene products with this or any other active ingredient on livestock or pets, even if there are veterinary products with this same active ingredient approved for use on animals. The formulations for agricultural or hygiene use are different and may be toxic for livestock or pets.

It is obvious that veterinary products are not intended for and should never be used on humans!!!


Decade of introduction: 1970
Introduced by: JANSSEN
Some original brands: FLUBENOL
Patent: Expired (particular formulations may be still patent-protected)

Use in LIVESTOCK: Yes, moderate, manily in pig and poultry
Use in DOGS and CATS: Yes, rather scarce

Main delivery forms: 

Use in human medicine: Yes
Use in public/domestic hygiene: No
Use in agriculture: No
Generics available:  Yes


In livestock: Yes, as all benzimidazoles, very frequent worldwide in gastrointestinal roundworms in sheep, goats and cattle, but not yet in swine or poultry.
In dogs and cats: No

Visit also the section in this site about parasite resistance to antiparasitics and more specifically to flubendazole.


Flubendazole is a veteran anthelmintic (wormer) compound belonging to the chemical class of the benzimidazoles. It is an analogue of mebendazole, another anthelmintic benzimidazole. Flubendazole is moderately used in pig and poultry, very scarcely in dogs, cats and ruminants.

For livestock flubendazole it is available in the form of feed additives, drenches, bolus, tablets, pills, etc, all for oral administration, mostly used alone. There are no classic injectables or pour-ons with flubendazole.

For dogs and pets flubendazole is usually available in the form of drenches and tablets, pills, etc.

For pets it is also used in mixtures that broaden the spectrum of activity, mostly with taenicide (e.g. praziquantel).

Efficacy of flubendazole

Flubendazole has a broad-spectrum of activity against gastrointestinal roundworms and lungworms of pig and poultry, including adults and larvae of the most important species (e.g. of the genus Ascaris, Ascaridia, Capillaria, Heterakis, Hyostrongylus, Oesophagostomum, Trichuris, etc.). It is also effective against some tapeworms (e.g. Taenia, Davainea, Raillietina, etc.).

It is also effective against the major parasitic roundworms (e.g. Ancylostoma, Toxocara, Trichuris, Uncinaria) and tapeworms (e.g. Taenia) of dogs and cats.

Flubendazole is absorbed slowly in the stomach. Therefore the longer it remains there, the better the efficacy. In carnivores (e.g. dogs and cats) and other animals with a simple stomach the passage through the stomach is rather fast and therefore a higher dosage or repeated treatments are usually required.

Flubendazole has no residual effect. This means that a single administration will kill the parasites present in the host at the time of treatment, but it will not protect against re-infestations.

At the therapeutic dose flubendazole is not effective against flukes and whatsoever external parasites.

Resistance of worms to benzimidazoles, including flubendazole in dogs, cats, pig and poultry is not a problem so far. However resistance of several gastrointestinal roundworms to all benzimidazoles, including flubendazole is already very high and very frequent worldwide in sheep and goats, slightly lower in cattle. For this reason, the risk that benzimidazoles fail to protect ruminants against gastrointestinal roundworms is considerable worldwide.

Pharmacokinetics of flubendazole

Flubendazole is almost insoluble in water. Orally administered flubendazole is poorly absorbed into the bloodstream. This means that significant amounts remain in the gastrointestinal tract and are available for the control of gut-dwelling roundworms and tapeworms. But blood levels are low and efficacy against tissue-dwelling worms may be lower or insufficient.

Absorbed flubendazole is quickly broken down in the liver to metabolites without anthelmintic efficacy. Both the parent molecule and its metabolites are excreted mainly through bile and feces, the rest through urine. However, there are important species-specific differences.

In dogs about 90% of the administered dose was excreted in the first 4 days after treatment, >80% through feces, most of it as unchanged flubendazole. About 6% was excreted through urine, most of it as various metabolites.

In pigs fed flubendazole during 5 days, ~80% of the administered dose was excreted within 30 days after end of the medication period. About 55% was excreted in feces and ~25% in urine.

In layers, flubendazole leaves very low residues in eggs, which allows low or nil withholding periods for eggs.

Mechanism of action of flubendazole

The molecular mode of action of all benzimidazoles, including flubendazole, consists in binding to tubulin, a structural protein of microtubules. These microtubules are important organelles involved in the motility, the division and the secretion processes of cells in all living organisms. In the worms the blocking of microtubules perturbs the uptake of glucose, which eventually empties the glycogen reserves. This blocks the whole energy management mechanism of the worms that are paralyzed and die or are expelled.

Since cell division is also disturbed, worm egg production and development is also blocked by benzimidazoles, i.e. most of them also have an ovicidal effect.

Click here to view the list of all technical summaries of antiparasitic active ingredients in this site.