Major Uses

Fenbendazole is an antiparasitic medication that belongs to the benzimidazole group of anthelmintics. It is a relatively broad spectrum medication and is typically used to remove roundworms, whipworms, and hookworms in both large and small animals. Fenbendazole is effective against Giardia, several lungworm species, some flukes, and Taenia species, but not against Dipylidium caninum.

Fenbendazole is available over the counter, but it should only be used under the guidance and supervision of a veterinarian.

Common Precautions

Nausea and vomiting may occur following treatment with fenbendazole. In some cases, dead worms may be present in the stool after treatment.

This medication is safe for use during pregnancy in all animals. Birds may develop bone marrow suppression and resulting anemia, low platelets, and low white blood cell counts after being treated with fenbendazole. Fenbendazole may be more effective if mixed with or given with food. With veterinarian approval, this dewormer can be administered with a small amount of food.

Fenbendazole should not be used in animals with a known allergy or hypersensitivity to the drug. It is unlikely that an overdose of this drug will be toxic. However, any unusual symptoms or behaviors following a known or suspected overdose should be reported to a veterinarian right away.


Fenbendazole should be stored in a tight fitting, light resistant container at room temperature. The medication should be kept far out of reach of children and pets.


Fenbendazole is available as an oral suspension, paste, and as granules.

For cats and dogs, fenbendazole should be administered at a dose of 25 mg per pound (50 mg/kg) daily. Fenbendazole should be continued for 3 to 5 consecutive days to eliminate most parasites. Depending on the parasite being treated, a second course of the drug may be necessary.

Doses may vary in different species, when the drug is given by a different route or concurrently with other medications, and with regards to a patient's age, breed, and health status. A veterinarian's dosing instructions and/or those printed on the medication label should be followed closely.

If a dose of this medication is missed, it should be given as soon as possible. If it is almost time for the next dose, the missed dose should be skipped and the regular schedule should be resumed. Two doses of this drug should not be given at once.

This information is for general reference only and should not be used for the diagnosis or treatment of any condition of your pet. It's intended as a general reference, this information may not include all possible uses, precautions, directions, reactions (including allergic), drug interactions, or withdrawal times. Always consult your local veterinarian and have your pet examined for any advice concerning the diagnosis and treatment of your pet, including which products and doses are most appropriate. Any trademarks are the property of their respective owners. VetDepot is not a pharmacy. All prescription products are dispensed by our Pharmacy Partner. Article last updated 2/2014.