Fenbendazole
Fenbendazole is a broad-spectrum anthelmintic (dewormer) medication primarily used in veterinary medicine to treat and control internal parasites. It belongs to the benzimidazole class of antiparasitic drugs and is effective against various nematodes and some cestodes in animals. The medication works by inhibiting microtubule synthesis in parasites, disrupting their cellular structure and energy metabolism, ultimately leading to their death.
A veterinary anthelmintic medication used to treat parasitic worm infections in animals including dogs, cats, horses, and livestock.
Key facts at a glance
- ATC
- P02CA06
- RxNorm
- 24821
- Generic
- Fenbendazole
- Class
- atc-p02
- Brands
- Panacur, Primacur, GiarcidiaZap-Wormer, Defendazole, Strideguard Dewormer, Safe-Guard
- Availability
- otc
- Pregnancy
- N
- Lactation
- unknown
- Half-life (h)
- 15
- Onset (min)
- 0
- Duration (h)
- 0
- Routes
- oral
- Forms
- granules, paste, suspension, chewable tablets, powder
- Regions
- United States, European Union, United Kingdom, Canada, Australia, New Zealand, South Africa, Asia, South America
- Monitoring
- liver enzymes, complete blood count
This page is for informational purposes only.
Do not use this information to diagnose yourself or to replace a physician's advice. Always consult a qualified healthcare provider before starting, stopping, or changing any medication. If you believe you are experiencing a medical emergency, call your local emergency number immediately.
Treatment of gastrointestinal parasites including roundworms (Toxocara, Toxascaris), hookworms (Ancylostoma, Uncinaria), whipworms (Trichuris), and some tapeworms (Taenia). Also used for lungworm infections and in horses for strongyles and encysted small strongyles.
Fenbendazole binds to tubulin in parasite cells, inhibiting microtubule polymerization essential for cellular structure and function. This disruption of the parasite's cytoskeleton impairs glucose uptake and transport, leading to depleted energy reserves and parasite death.
Generally well-tolerated with a wide safety margin in most animal species. FDA-approved for veterinary use; extra-label use requires veterinary prescription. Safety in breeding, pregnant, or lactating animals should be confirmed with a veterinarian. Resistance has been reported in some parasite populations with repeated use.
Official drug label
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This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.
This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.
If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.
Medically reviewed by WellAlly Editorial Team Last reviewed August 25, 2026. · Read our editorial policy