Brand: FASINEX ® 100 Oral Suspension


FORMULATION: «drench» for oral administration.

ACTIVE INGREDIENT(S): triclabendazole: 100 g/L (=10%)

CHEMICAL CLASS of the active ingredient(s): benzimidazole


*Goats not in the UK

PARASITES CONTROLLED (spectrum of activity)

  • Liver fluke infections caused by all stages of Fasciola hepatica from 2 day old immature to adult fluke.


  • Sheep & Goats: 1 ml product/10 kg bw, equivalent to 10 mg triclabendazole/kg bw.
  • Cattle: 3 ml product/25 kg bw, equivalent to 12 mg triclabendazole/kg bw.


  • LD50 (acute oral) in rats: >5000 mg/kg (according to MSDS).
  • LD50 (acute dermal) in rats: >4000 mg/kg (according to MSDS).

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

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

  • Meat:
    • Cattle: UK: 56 days; Australia: 21 days (ESI 56 days); New Zealand 28 days.
    • Sheep: UK: 35 days; Australia: 21 days (ESI 63 days); New Zealand 28 days.
    • Goats: Australia: 21 days (ESI 63 days); New Zealand 28 days.
  • Milk for human consumption: 
    • UK: Not authorised for use in cattle producing milk for human consumption including during the dry period. Do not use during the last trimester of pregnancy in heifers which are intended to produce milk for human consumption.
    • Australia: DO NOT USE in lactating animals where milk or milk products may be used for human consumption. DO NOT USE less than 21 days before calving, lambing or kidding in cows, ewes or does where milk and milk products from treated animals may be used for human consumption. Lambs or kids fed this milk should not be slaughtered for human consumption within 7 days. Calves fed this milk should not be slaughtered for human consumption within 10 days.
    • New Zealand: Milk intended for human consumption must be dircarded during treatment for not less than 70 milkings or approximately 35 days following the last treatment.

The different withholding periods in various countries illustrate the fact that unfortunately, national regulatory authorities often draw different conclusions from the same scientific evidence. This has been always so and there are no indications that things will improve in the near future.

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

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


Risk of resistance of Fasciola hepatica to triclabendazole: YES. Resistance of liver flukes to triclabendazole (and albendazole) in sheep was already discovered in the mid 1990's in Australia. Since then it has been reported in several other countries (e.g. New Zealand, UK, Ireland, Spain, Argentina), also in cattle (e.g. Australia, The Netherlands, Argentina). However, the incidence so far is not that serious as for roundworm resistance to benzimidazoles and other nematicides. Nevertheless, in certain regions products with triclabendazole may not protect livestock adequately against liver flukes.

This means that if this product does not achieve the expected efficacy against the mentioned parasites, it may 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 liver flukes through product rotation:

These alternative products may not be available in all countries or may not be available as drenches.

There are also a few reports on liver fluke populations in sheep resistant to rafoxanide and closantel (both salicylanilides), probably with cross-resistance to nitroxinil, and also to clorsulon. So far resistance to these compounds seems to be less frequent than to resistance to benzimidazoles.

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: UK and EU countries, Australia, New Zealand.
GENERIC BRANDS available? Yes in most countries.

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

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


FASINEX is the original brand of triclabendazole drenches from CIBA-GEIGY (later NOVARTIS, NOW ELANCO), introduced in the late 1970s.

Triclabendazole is a narrow-spectrum benzimidazole introduced in the 1970s (by CIBA-GEIGY). It has no efficacy against roundworms or tapeworms. However it was and remains the only flukicide effective against adults as well as all immature stages of liver flukes, which are the most damaging stages due to their destructive migration through the liver tissues. For this reason it has been for decades and still remains the most widely used livestock flukicide worldwide. It is ineffectivy against any external parasites (ticksflies, lice, mites, etc) of livestock. It is abundantly used in ruminants, but not in other livestock, horses or pets. It is also used in human medicines. It is not used in agriculture.

Because it is effective against all stages of immature flukes, triclabendazole is appropriate to treat acute fascioliasis, caused my massive infections with larvae migrating through the liver.

As all benzimidazoles (and many other anthelmintics such as levamisole, monepantel, and tetrahydropyrimidines), triclabendazole administered as a drench has no residual effect, i.e. it kills the parasites shortly after administration, but does not significantly protect the animals against re-infestation by infective stages in their environment.

Triclabendazole is often used in combinations that broaden the spectrum of activity, mainly to add efficacy against roundworms. Typical mixtures include a macrocyclic lactone (e.g. abamectinivermectin, moxidectin) or levamisole.

In ruminants, reducing the amount of feed slows down the exit flow of the rumen and prolongs the time during which the active ingredient remains there and is absorbed. Consequently it is advisable to reduce the access of animals to feed (especially to fresh pasture, not to water) 24 hours before administration. For the same reason, it is better to keep the animals away from food for about 6 hours after drenching. However sick or weak animals should not be kept away from food and fasting animals should have access to water. In cattle, a fiber-rich diet also increases the bioavailability of fenbendazole.

Triclabendazole active ingredient is a solid compound poorly soluble in water and in drenches it is formulated as a suspension (not as a solution or as an emulsion). A key unfavorable feature of all suspensions is that the suspended solid particles tend to fall down to the bottom of the container and sediment, very much like sand in water. This means that suspensions must be thoroughly shaken before use. How fast the suspension sediments and how easily shaking the container redistributes the suspension depends on the formulation quality. A good formulation sediments slowly and shaking will re-suspend it quickly. Bad formulations sediment quickly and shaking re-suspends them slowly.

Thoroughly shaking suspensions before use is crucial for efficacy. If the active ingredient remains in the sediment, a few animals may get most of the active ingredient and will be overdosed, and the large majority will get almost only solvents and will be underdosed.


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.