Brand: LEVAMISOLE Pour-on for Cattle

Company: VIRBAC

FORMULATION: «pour-on» for topical administration. To be applied evely in a stripe along the backline of the animal.

ACTIVE INGREDIENT(S): levamisole: 200 g/L (= 20%)

CHEMICAL CLASS of the active ingredient(s): imidazothiazole


PARASITES CONTROLLED (spectrum of activity)


  • Cattle: 2.5 ml product/50 kg bw, equivalent to 10 mg/kg bw


  • LD50 (acute oral) in rats: for the a.i. 180 mg/kg (according to MSDS)
  • LD50 (acute dermal) in rats: n.a.
  • Estimated hazard class according to the WHO: not applicable for veterinary medicines

Suspected poisoning? Read the article on levamisole safety in this site.

Withholding periods (=withdrawal times) for meat & milk (country-specific differences may apply: read the product label)

  • Meat: Australia 3 days (ESI 7 days)
  • Milk for human consumption: 24 hours. Milk collected during this time should not be fed to bobby calves.

WARNING !!!: Never use on humans, dogs and cats

You may be interested in the following articles in this site dealing with the general safety of veterinary products:


Risk of resistance? YES, resistance of gastrointestinal roundworms to levamisole in ruminants is a serious and increasing problem, particularly in sheep and goats, but also in cattle. Levamisole resistance is usually less strong and widespread than resistance to benzimidazoles, but nevertheless a serious problem. The most affected worm species are:

Based on the very abundant and frequent use of levamisole in livestock it must be assumed that resistance of these roundworms to this chemical class will continue spreading and strengthening in the future.

This means that if this product does not achieve the expected efficacy against the mentioned parasites, it can be due to resistance and not to incorrect use, which is usually the most frequent cause of product failure.

Alternative chemical classes/active ingredients to prevent resistance of gastrointestinal roundworms through product rotation:

These alternative products may not be available in all countries, or may not be available as pour-ons.

Learn more about resistance and how it develops.


Are the active ingredients of this product ORIGINAL* or GENERICS**?


*Meaning that they are still patent protected and generics are not yet available
**Meaning that they have lost patent protection and may be acquired from manufacturers of generic active ingredients other than the holder of the original patent.

COUNTRIES where this brand/product is marketed (maybe under another TM): Australia
GENERIC BRANDS available? YES, but rather few pour-ons in most countries.

Click here to learn more about GENERIC vs. ORIGINAL drugs.

For an overview on the most used antiparasitic pour-on brands click here.


LEVAMISOLE Pour-on for Cattle from VIRBAC is one of the numerous wormers for livestock containing levamisole.

Levamisole is a veteran anthelmintic. It was introduced by JANSSEN already in the 1960s (NILVERM, RIPERCOL). It has a broad-spectrum of activity against roundworms (gastrointestinal and pulmonary) but no efficacy whatsoever against tapeworms and flukes. It is also completely ineffective against external parasites of livestock (ticksflies, lice, mites, etc). Levamisole has been used massively worldwide in countless generic formulations, not only oral drenches but also pour-ons, injectables as well as additives for feed and drinking water. It still remains one of the most preferred low-cost anthelmintics for livestock worldwide. Usage is rather scarce in pets and horses. It is not used in agriculture.

Levamisole is mostly used in drenches for oral administration, and in some countries also in injectables. Pour-on administration is often more convenient than those other delivery forms, but has also disadvantages. In several scientific studies it has been shown that topically administered antiparasitics (e.g. ivermectin, fluazuron) are not "automatically" absorbed through the skin. Licking (self licking or licking of other treated animals) may account for >50% of the total intake. And individual cattle show a different licking behavior. An important practical consequence is that the quantity that is finally ingested and is therefore available for the control of gastrointestinal worms depends on the licking behavior of the treated animals. "High lickers" can be overdosed, whereas "low lickers" can be underdosed. And chronic underdosing of animals in a herd may enhance development of resistance to ivermectin in gastrointestinal roundworms. To our knowledge such effect of licking on topically administered levamisole has not been investigated but must be assumed.

Absorption through the skin is also negatively affected by the thickness of the skin and the hair coat, by dust and mud on the coat, by product lost on fences and yards, etc, factors that don't play a role after injection or drenching. In contrast with drenches or injectables, pour-on formulations should not be administered to wet animals, and rain shortly before (up to 6 hours) or after administration can cause product run-off and thus under-dosing. The pour-ons shouldn't be administered by strong winds that may blow away part of the product and/or contaminate the workers.

For all these reasons efficacy after pour-on administration is usually less reliable than after oral administration or injection.

There are also numerous mixtures of levamisole with other active ingredients.

Click here for general information on good practices for the prevention and control of gastrointestinal worms in livestock.


This article IS NOT A PRODUCT LABEL. It offers complementary information that may be useful to veterinary professionals and users that are not familiar with veterinary antiparasitics. 

Information offered in this article has been extracted from publications issued by manufacturers, government agencies (e.g. EMEA, FDA, USDA, etc.) or in the scientific literature. No guarantee is given on its accuracy, integrity, sufficiency, actuality and opportunity, and any liability is denied. Read the site's DISCLAIMER.

In case of doubt contact the manufacturer or a veterinary professional