The label says, word for word:
For the treatment and control of Roundworms (Toxocara canis, Toxascaris leonina), Hookworms (Ancylostoma caninum, Uncinaria stenocephala), Whipworms (Trichuris vulpis), and Tapeworms (Taenia pisiformis).
Keep this and all medication out of the reach of children.
Do not deworm a dog or puppy that is sick. Consult your veterinarian for diagnosis of the illness.
Panacur® C is safe for use in puppies 6 weeks or older and adult dogs, including pregnant bitches.
Panacur® C only kills Taenia species of tapeworms. If you continue to see tapeworm segments in your dog's stool after treatment with Panacur® C, consult your veterinarian.
Every approved medicine has a field study behind it, and the label prints what happened:
In US clinical studies 3 of 240 dogs (about 1% of the treated dogs) had vomiting associated with use of the product.
'Approved by FDA under NADA # 121-473'. DailyMed classes Panacur C as an OTC animal drug label (no 'Federal law restricts' statement); the FOI summary for a supplement to NADA 121-473 describes a change from prescription to over-the-counter status for 'PANACUR-C (fenbendazole) Granules 22.2%' and references the original approval date of '27 October 1983'; FDA's 2024 Dear Veterinarian letter states 'Fenbendazole was first approved for use in dogs on November 2, 1983.'
The emergency page sorts the signs by how long you have, and the symptom checker asks what you are seeing. Reactions to a medicine can also be reported to the FDA yourself: how to report a problem.
These answers come from the approved label on DailyMed, read on 2 October 2026. Where the label does not say, the answer says so, and the vet or the pharmacist is the one to ask.
The approved use is quoted at the top of this page. The label read for these answers is the one for Panacur C, a dewormer for dogs that is sold without a prescription. It treats and controls roundworms, hookworms, whipworms and one kind of tapeworm.
The label gives no time. Ask the vet what to expect and by when. The label does say that Panacur C kills only Taenia tapeworms, and to see the vet if you still see tapeworm segments in your dog's stool after treatment.
The granules are mixed into a small amount of the dog's usual food, once a day for three days in a row. The label says to make sure your dog eats all of the medicated food, and that dry food may need moistening so the granules mix in. It tells you to weigh your dog first, because the amount goes by weight and the packets come in different sizes. It says the product is safe for puppies six weeks or older and for adult dogs, including pregnant dogs.
The label does not say what to do about a missed dose. Call the clinic or the pharmacy before you give the next one.
The studies and the warnings are quoted above. The label has no line telling owners when to call the vet. It does say not to deworm a dog or puppy that is sick, and to see the vet about the illness instead. If your dog seems unwell after a dose, call the vet.
Store it at room temperature, between 68° and 77°F. Keep it out of the reach of children.
The FDA says the best way to get rid of most unused or expired medicines is a take-back option: a drug take-back location, which can be at a pharmacy or a police station, or a prepaid mail-back envelope. If you cannot use one and the medicine is not on the FDA's flush list, the FDA says to mix it with something unappealing such as dirt, cat litter or used coffee grounds and to seal the mixture in a plastic bag before throwing it away. Flushing is only for medicines on that list, such as opioids. Do not give leftovers to another pet.
Write the dose, the times and the stop date here, then print this page for the fridge.
Dose and times: _____________________________________________
Stop date: _____________________________________________