Ricobendazole is an antiparasitic active ingredient used in veterinary medicine mainly in livestock against internal parasites (roundworms, tapeworms, and liver flukes).

It is not used against agricultural and household pests. It belongs to the chemical class of the benzimidazoles.


Type: veterinary medecine
Chemical class: benzimidazole


Molecular structure of RICOBENDAZOLE 


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

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.


Ricobendazole is a broad-spectrum anthelmintic effective against roundworms and, depending on the dose also against some tapeworms (e.g. Moniezia spp) and flukes (e.g. Fasciola hepatica adults). It is completely ineffective against external parasites. It is the only benzimidazole that can be administered by injection but is also availlable for drenching. It is abundantly used in ruminants in some countries (e.g. in Latin America) but only scarcely elsewhere. Use in pets or horses is very rare.

In ruminants, a 50% reduction of the diet 36 prior and 8 hours after oral treatment slows down the passage through the stomach, which increases the bioavailability of benzimidazoles and their metabolites and consequently its efficacy against gastrointestinal parasites.

In carnivores (incl. dogs and cats) delivery with the food increases the bioavailability of all benzimidazoles resulting in a better efficacy.

All benzimidazoles have almost no residual effect, i.e. they kill the parasites during a few hours after treatment but offer no significant protection against re-infestation.

The table below indicates some usual dosing recommendations for ricobendazole issued by manufacturers or documented in the scientific literature. They may not be approved in some countries.

Dosing recommendations for RICOBENDAZOLE
Delivery Parasites Dose (against ricobendazole-susceptible parasites)
Oral (tablets) Roundworms 24 mg/kg
Oral (susp.) Roundworms 30 mg/kg. Severe infestation: repeat after 24 h
Delivery Parasites Dose (against ricobendazole-susceptible parasites)
Oral Roundworms
30 mg/kg. Severe infestation: repeat after 24 h
Delivery Parasites Dose (against ricobendazole-susceptible parasites)
Injectable Roundworms & tapeworms 2.5-8 mg/kg dep. on indications
Injectable Ostertagia spp inhibited larvae 5-7.5 mg/kg
Injectable Fasciola hepatica adults 5 mg/kg
Oral Roundworms (gastrointestinal) 3 mg/kg
Oral Ostertagia spp inhibited larvae 4.5 mg/kg
Oral Roundworms (respiratory) 6 mg/kg
Oral Fasciola hepatica adults 6 mg/kg
Oral Tapeworms (Moniezia spp) 6 mg/kg
Delivery Parasites  Dose (against ricobendazole-susceptible parasites)
Injectable Roundworms & tapeworms 3.4-7.5 mg/kg dep. on indications
Injectable Ostertagia spp inhibited larvae 5-7.5 mg/kg
Injectable Fasciola hepatica adults 6.8 mg/kg

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Dosing recommendations for antiparasitics depend on national regulations. National regulatory authorities determine whether a product is approved for a given indication, i.e. use on a particular host at a specific dose and against a specific parasite. Check the labels of the products available in your country for specific information on approved indications.


Oral LD50, rat, acute*: 2400 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.

WARNING: Ricobendazole, as well as albendazole, parbendazole and cambendazole can be teratogenic and should not be administered to pregnant females.

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

  • CODEX: Yes
  • EU: Yes
  • USA: Yes
  • AUS: Yes

* 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.

General information on the safety of veterinary antiparasitics is available in specific articles in this site (click to visit):


Never use products for livestock on dogs and cats unless they are explicitly approved for both livestock and pets. Pets may not tolerate livestock formulations

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


Decade of introduction: 1980
Introduced by: Robert Young
Some original brands: RYCOBEN, ALLVERM
Patent: Expired (particular formulations may be still patent-protected)

Use in LIVESTOCK: Yes, moderate
Use in DOGS and CATS: Yes, very scarce

Main delivery forms

Use in human medicine: No
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.
In dogs and cats: No

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


Ricobendazole is a veteran anthelmintic (wormer) compound belonging to the chemical class of the benzimidazoles.

It is moderately used in livestock, mainly in cattle, scarcely in sheep and goats. It is available in the form of injectables and drenches. Use in dogs and cats either as drenches or tablets, pills, etc, is marginal.

Ricobendazole is "the" injectable benzimidazole. Chemically ricobendazole is albendazole sulfoxide, the major metabolite of albendazole. Benzimidazoles are very poorly soluble in water, and therefore cannot be injected, because they "get stuck" at the injection site. They have to be delivered orally (in drenches, boluses, tablets, etc.). Ricobendazole is significantly more soluble in water than albendazole and can be injected. However, whereas it is quite popular in several regions (e.g. Latin America) it is not used at all in others (e.g. the EU).

Efficacy of ricobendazole

Ricobendazole has basically the same broad-spectrum of efficacy as albendazole, although the effective dose for certain parasites may be slightly different. Ricobendazole is effective against gastrointestinal roundworms and lungworms of livestock, including adults and L4-larvae of the most important species (e.g. of the genus Bunostomum, Haemonchus, Ostertagia - Teladorsagia, Trichostrongylus, Cooperia, Nematodirus, Chabertia, Oesophagostomum, Trichuris, Dictyocaulus, etc.) as well as arrested larvae of several species. It is also effective against most livestock tapeworms (e.g. Moniezia) and against adult liver flukes (Fasciola hepatica and Fascioloides magna), but not against immature stages.

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

Ricobendazole has only a limited residual effect. This means that a single administration will kill the parasites present in the host at the time of treatment and protect against re-infestations for a few days, but not for weeks. In non-ruminants the residual effect is substantially shorter, i.e. only a few hours.

Ricobendazole has no efficacy whatsoever against external parasites.

Unfortunately, resistance of several gastrointestinal roundworms to all benzimidazoles, including ricobendazole is already very high and very frequent worldwide in sheep and goats, slightly lower in cattle. Resistance of the liver fluke (Fasciola hepatica) is not that dramatic, but spreading in many countries. For this reason, the risk that benzimidazoles fail to protect ruminants against gastrointestinal roundworms is considerable worldwide.

Worm resistance to benzimidazoles in dogs, cats, pig and poultry are so far not a serious problem.

Pharmacokinetics of ricobendazole

Injected ricobendazole is rapidly absorbed into the bloodstream. Maximum plasma levels are reached about 5 hours after administration. It is quickly distributed throughout the whole body and appears also in the abomasum, where it is partly reduced to albendazole.

Excretion in ruminants is mainly through urine, in the form of the parent molecule or various metabolites.

Mechanism of action of ricobendazole

The molecular mode of action of all benzimidazoles, including ricobendazole, 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.

Ricobendazole also inhibits a helminth-specific fumarate reductase, an enzyme involved in the energy management of the worm cells as well.

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