By Rania Gollakner, BS, DVM, MPH

What is fenbendazole?

Fenbendazole (brand names Panacur®, Safe-Guard®) is a medication used to treat a variety of parasites (e.g., roundworms, hookworms, lungworm, whipworm, and certain types of tapeworms) in dogs. Its use in cats for the treatment of parasites is 'off label' or 'extra label'. Many drugs are commonly prescribed for off label use in veterinary medicine. In these instances, follow your veterinarian’s directions and cautions very carefully.

How is fenbendazole given?

Fenbendazole comes as oral granules or as a liquid suspension and is given by mouth. Liquid forms must be measured carefully.

Fenbendazole should be given with food to reduce gastrointestinal upset.

Give this medication as directed by your veterinarian. Fenbendazole is often given once daily for 3 consecutive days and then again in another round 2-3 weeks later.

It is important that your pet receives all of the doses recommended by your veterinarian for best results. Do not stop early or skip doses unless recommended by your veterinarian. Retreatment may be necessary if doses are missed, the medication is stopped too soon, or if reinfection from the environment occurs.

This medication should take effect within 1 to 2 days, but visible effects will take the entire duration of treatment to be recognized.

What if I miss giving my pet the medication (or my shipment is late)?

If you miss a dose, give it when you remember. If it is close to the time for the next dose, skip the missed dose and give it at the next scheduled time. Never give your pet two doses at once or give extra doses.

Are there any potential side effects?

At regular doses, fenbendazole does not usually cause any side effects. Sometimes, substances released by the dying parasites may cause an allergic reaction, especially if fenbendazole is given at higher than regular doses. If your pet shows signs of an allergic reaction (facial swelling, itchiness, hives, diarrhea, seizures, or shock) seek veterinary care immediately.

Salivation, vomiting, and diarrhea may occur in dogs or cats receiving this medication.

This moderate-acting medication should stop working in a few days, although effects can be longer in pets with liver or kidney disease.

Are there any risk factors for this medication?

Fenbendazole is safe for use in most pets. Fenbendazole should not be used in:

  • puppies younger than 6 weeks of age.
  • sick animals


Are there any drug interactions I should be aware of?

While there are no known drug interactions with fenbendazole, be sure to tell your veterinarian about any medications (including vitamins, supplements, or herbal therapies) that your pet is taking.

Is there any monitoring that needs to be done with this medication?

Your veterinarian may recommend a fecal examination to be sure that all internal parasites have been killed and determine if additional doses are needed.

How do I store fenbendazole?

Store fenbendazole granules in a tightly sealed container at room temperature and protected from sunlight.

If your veterinarian has made a special formulation for your pet, follow the storage recommendations on the label and expiration date for the product.

What should I do in case of emergency?

If you suspect an overdose or an adverse reaction to the medication, call your veterinary office immediately. If they are not available, follow their directions in contacting an emergency facility.

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