The label says, word for word:
CREDELIO kills adult fleas and is indicated for the treatment and prevention of flea infestations (Ctenocephalides felis) and the treatment and control of tick infestations [Amblyomma americanum (lone star tick), Dermacentor variabilis (American dog tick), Ixodes scapularis (black-legged tick), Rhipicephalus sanguineus (brown dog tick), and Haemaphysalis longicornis (longhorned tick)] for one month in dogs and…
There are no known contraindications for the use of CREDELIO.
There are no known contraindications for the use of CREDELIO CAT.
Lotilaner is a member of the isoxazoline class. This class has been associated with neurologic adverse reactions including tremors, ataxia, and seizures.
Seizures have been reported in dogs receiving isoxazoline class drugs, even in dogs without a history of seizures. Use with caution in dogs with a history of seizures or neurologic disorders.
Neurologic adverse reactions have been reported in cats receiving isoxazoline class drugs, even in cats without a history of neurologic disorders. Use with caution in cats with a history of neurologic disorders.
The safe use of CREDELIO in breeding, pregnant or lactating dogs has not been evaluated.
Keep CREDELIO in a secure location out of reach of dogs, cats, and other animals to prevent accidental ingestion or overdose.
Every approved medicine has a field study behind it, and the label prints what happened:
In a well-controlled U.S. field study, which included 284 dogs (198 dogs treated with CREDELIO and 86 dogs treated with an oral active control), there were no serious adverse reactions.
Dog field study table (CREDELIO group): Weight Loss 3 (1.5%); Elevated Blood Urea Nitrogen (BUN) 2 (1.0%); Polyuria 2 (1.0%); Diarrhea 2 (1.0%)
In a well-controlled U.S. field study, which included 341 cats (228 cats treated with CREDELIO CAT and 113 cats treated with a topical active control), there were no serious adverse reactions.
Credelio (dogs): Approved by FDA under NADA 141-494 (FOI 'Date of Approval: January 19, 2018').
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. It is a chewable tablet given once a month to kill fleas and the ticks the label names. The label read for these answers is the one for dogs, which covers dogs and puppies from 8 weeks of age that weigh 4.4 pounds or more. Credelio CAT, the tablet for cats, has a label of its own, which is in the sources below.
The label says that in laboratory studies Credelio began to kill fleas four hours after the dog was given it, and that more than 99% of the fleas were killed within eight hours. Against the ticks it names, the label reports that Credelio was more than 97% effective 48 hours after the tablet.
It is given by mouth once a month. The label says it must be given with food, either with a meal or within 30 minutes after feeding, because less of the drug is absorbed on an empty stomach. Treatment can start at any time of the year and can go on all year round without a break. The label does not say what to do if the dog vomits soon after the tablet.
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 that drugs of this class have been linked to tremors, unsteady walking and seizures, and that seizures have been reported even in dogs with no history of them. If you see any of these, or your dog seems unwell after a dose, call the vet.
Store it between 59° and 77°F; the label allows short spells between 41° and 104°F. Keep it out of the reach of children. The label also says to keep it in a secure place out of reach of dogs, cats and other animals, to prevent accidental swallowing or an overdose.
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, uncrushed, 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: _____________________________________________