The label says, word for word:
ONSIOR (robenacoxib) injection is indicated for the control of postoperative pain and inflammation associated with orthopedic surgery, ovariohysterectomy and castration in cats ≥ 4 months of age; for up to a maximum of 3 days. ONSIOR (robenacoxib) injection is indicated for the control of postoperative pain and inflammation associated with soft tissue surgery in dogs ≥ 4 months of age; for up to a maximum of 3 days.
ONSIOR tablets should not be used in cats that have a hypersensitivity to robenacoxib or known intolerance to NSAIDs.
ONSIOR (robenacoxib) should not be used in dogs that have a hypersensitivity to robenacoxib or known intolerance to NSAIDs.
Not for use in humans. Keep this and all medications out of reach of children. Consult a physician in case of accidental ingestion by humans. For oral use in cats only.
Do not administer ONSIOR tablets or injection in conjunction with any other oral or injectable NSAID or corticosteroid.
Do not use for more than 3 days.
The use of ONSIOR tablets has not been evaluated in cats younger than 4 months of age and weighing less than 5.5 lbs, cats used for breeding, or in pregnant or lactating cats.
The safe use of ONSIOR has not been evaluated in dogs younger than 4 months of age, dogs used for breeding, or in pregnant or lactating dogs.
Every approved medicine has a field study behind it, and the label prints what happened:
Tablets, cats: "The most commonly reported adverse reactions were surgical site bleeding, infected surgery sites, lethargy, vomiting and inappetance." Field study counts (ONSIOR vs placebo): Incision site bleeding 7 vs 1; Incision site infection 6 vs 2; Inappetance, weight loss 4 vs 2; Decreased activity, lethargy 4 vs 1; Vomiting 4 vs 1.
From the sheet the maker writes for owners:
Two labels: ONSIOR tablets (cats only, NADA 141-320; tablet indication: "ONSIOR tablets are indicated for the control of postoperative pain and inflammation associated with orthopedic surgery, ovariohysterectomy and castration, in cats ≥ 5.5 lbs (2.5 kg) and ≥ 4 months of age; for up to a maximum of 3 days.") and ONSIOR injection (cats and dogs; NADA 141-443). Short-course drug: maximum 3 days in both species.
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 Onsior tablets, which are given to cats to control pain and inflammation after orthopedic surgery, spaying or castration, for no more than three days. Onsior injection has a label of its own.
The label reports a rapid start, about half an hour, in a laboratory model of inflammation in cats. It also says the level of the drug in the blood peaks about half an hour after a tablet.
The tablets are given by mouth, once a day and for no longer than three days, and the label says they may be given with or without food. They are not scored and should not be broken. The first dose is given about 30 minutes before surgery, so the clinic gives that one, and the cat may also have had an Onsior injection there. The owner sheet that comes with the label says a cat should not get more than one dose a day or more than three doses in total, so follow the vet's instructions on how many are left to give at home.
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 owner sheet does say that a cat should not get more than one dose in a day.
The studies and the warnings are quoted above. The owner sheet says to stop giving the tablets and call the vet if your cat eats less, vomits, has diarrhea or a change in the color of its stool, drinks or urinates differently, or behaves differently, for example seems depressed or restless. It also says to contact the vet immediately if your cat eats more than the prescribed amount.
Store the tablets at room temperature, between 59° and 77°F. Keep them 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, 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: _____________________________________________