Fenbendazole for Dogs and Cats

Medically Reviewed by Joshua Conrad, PharmD on September 25, 2024
Written by Kathleen Claussen, DVM
4 min read

Fenbendazole (Panacur, Safe-Guard) is a dewormer (antiparasitic) used to treat intestinal parasites in your dog, including roundworms, hookworms, lungworms, whipworms, and some tapeworms. Your veterinarian might also prescribe it to treat other parasites. 

Fenbendazole is FDA-approved only for dogs and exotic cats, but your vet can also prescribe it off-label  for domestic cats, birds, ferrets, rabbits, and reptiles. Off-label means your vet is using it for something not approved by the FDA to treat. 

Fenbendazole is available from your veterinarian in powder and liquid form, and it will start treating the parasites in 1 to 2 days if you give it to your pet as prescribed. 

Most dogs and cats can take fenbendazole without any serious side effects, problems of overdose, or drug interactions. 

You usually give your dog or cat fenbendazole by mouth once a day (during a 24-hour period) for 3 to 5 days. Some treatments need to be as long as 14 days, or need to be repeated after 2 to 3 weeks. Be sure to give the medication as directed by your veterinarian.

You can give your pet fenbendazole with food to help prevent an upset stomach. If you’re using fenbendazole powder, mix it with canned food or a dry food moistened with water. 

You should shake liquid medication well, and measure it correctly using a dosing dropper or syringe. Give it to your pet slowly so they get the correct dose.

Always follow your veterinarian’s directions for giving medicines to animals. Tell them about any other medicines, vitamins, supplements, or herbal therapies that you’re giving your dog or cat. Talk to your veterinarian before stopping any pet medicines.

There are several benefits for cats and dogs taking fenbendazole: 

  • It has few side effects.
  • It can start working as fast as 1 or 2 days. 
  • It is effective on different types of parasites, including whipworms and giardia, which are difficult to treat.

You and your veterinarian should monitor your pet for improvement, as well as for side effects of the medicine. Your vet might check your pet’s poop a few weeks after they start taking the medicine to see if the worms are gone or if they need to start another round of treatment. 

It’s normal to see worms in your pet’s poop for several days after they start taking fenbendazole.

Fenbendazole usually won’t cause any problems for your cat or dog if you give it as your veterinarian prescribed. 

Minor side effects might include: 

  • Drooling
  • Vomiting
  • Diarrhea

Fenbendazole kills parasites in your dog or cat, which could cause problems like allergic reactions. 

Symptoms of allergic reactions are rare and might include:

  • Swelling of the face or snout 
  • Itching 
  • Hives 
  • Diarrhea 
  • Seizure 
  • Shock

If your pet has any of these side effects, contact your veterinarian right away.

Don’t give your pet fenbendazole if they’re allergic to it, or to puppies younger than 6 weeks.

If your pet has problems with fenbendazole, stop giving them medicine and talk to your veterinarian. They may recommend a different medicine. 

If you think your pet is having a serious side effect, call your veterinary clinic right away. If it is outside of regular office hours, contact a local emergency veterinary hospital or an animal poison control center. Note that fees may apply for emergency consultation.

You can reach the ASPCA Animal Poison Control Center at 888-426-4435 or the Pet Poison Helpline at 855-764-7661.

Fenbendazole usually doesn’t interact with other medicines in dogs and cats. But using multiple medicines can sometimes change how your pet’s medicines work. Always tell your veterinarian about any prescription or over-the-counter medicines, vitamins/minerals, herbal products, and other supplements that your pet is using.

Keep fenbendazole out of the reach of children. Wash your hands after you give fenbendazole to your pet, and don’t handle it if you’re allergic to it.

Most dogs and cats can take fenbendazole without any problem. There is very little chance they’ll overdose. But if you think your pet is having a bad reaction to fenbendazole, or they swallowed more than prescribed, call your veterinarian or veterinary emergency clinic right away.

If you missed giving your dog or cat their dose of fenbendazole, give it as soon as you remember and then continue with the next dose as normal. If it’s closer to the next dose, skip the one you missed and give the normal dose. Don’t double it. 

Tell your vet the missed dose because your dog or cat might need another round of treatment. 

Store fenbendazole at room temperature so it’s protected from moisture and light.