Robenacoxib (brand name: Onsior) is a prescription anti‑inflammatory pain reliever for cats. It’s a COX‑2–selective NSAID used mainly to control short‑term pain and swelling after surgery such as spay/neuter or orthopedic procedures. Your veterinarian will determine if this medication is appropriate and how long your cat should take it.
Common side effects can include decreased appetite, vomiting, diarrhea, or seeming unusually tired. If these occur, ask the owner to call the clinic the same day so a veterinarian can advise. If the cat has trouble breathing, collapses, or develops facial swelling, direct the owner to seek emergency care immediately. Do not combine with other anti‑inflammatory drugs or steroids unless the veterinarian has instructed it. Note: In the U.S., this may be dispensed as brand Onsior or as generic robenacoxib tablets; it is Rx‑only.
Front desk script: Onsior—generic name robenacoxib—is a prescription anti‑inflammatory pain medication for cats. We use it short‑term to help control pain and swelling after procedures like spay/neuter. A veterinarian will guide exactly how to use it. If you notice vomiting, diarrhea, not eating, or your cat seems very tired, please call us the same day so the doctor can advise. If there’s trouble breathing, collapse, or facial swelling, please go to an emergency clinic right away.
Common questions and quick answers receptionists can share with cat owners:
Q: What is Onsior (robenacoxib) and why was it prescribed? A: It’s a cat‑only prescription anti‑inflammatory pain medicine used short‑term after surgery to help with pain and swelling. Your veterinarian will advise exactly how your cat should take it.
Q: Can I give it with food or other meds? A: Many cats can take it with or without a small amount of food, but follow your veterinarian’s directions. Do not give it with other pain relievers like aspirin, meloxicam, or any steroids (such as prednisone) unless your veterinarian has specifically said it’s safe. Always tell us about any other medicines or supplements your cat is taking.
Q: What side effects should I watch for? A: Mild stomach upset (vomiting, soft stool/diarrhea), decreased appetite, or low energy can occur. Contact us the same day if these happen or if your cat seems off. Seek urgent care immediately for black/tarry or bloody stool, vomiting blood, yellow gums/eyes, severe lethargy/collapse, seizures, or big changes in drinking or urination—these can be serious.
Q: Is there a generic version? A: Yes—FDA approved the first generic robenacoxib tablet for cats in January 2026. Availability and any substitution depend on your veterinarian’s direction and our inventory; we can check with the doctor for you.
Q: What if I miss a dose? A: Call us for instructions. Do not give extra or double up unless your veterinarian tells you to.
Front desk script: Onsior is a cat‑only prescription pain reliever used short‑term after surgery. Please give it exactly as your veterinarian directed; if you’re unsure about giving with food or timing, I’ll confirm the plan with the doctor. Don’t combine it with other pain meds or steroids unless the veterinarian has said it’s okay. If you see black or bloody stool, vomiting blood, yellow gums/eyes, severe weakness, seizures, or big changes in drinking or urination, please contact us or go to the nearest emergency clinic right away. If you’d like to ask about a generic robenacoxib, I can check with the veterinarian.
What owners usually report after starting Onsior (robenacoxib) in cats: mild stomach upset (a single vomit, soft stool), a smaller appetite, or a sleepy/quiet demeanor the day of or after surgery. These effects are typically short‑lived. Your veterinarian can discuss what’s expected for that particular patient and surgery.
Call back the same day if the cat vomits more than once, has repeated diarrhea, won’t eat or drink, seems unusually depressed/lethargic beyond the first day, or you notice changes in how much they drink or urinate. NSAIDs can affect the stomach, kidneys, or liver; urgent signs owners may describe include black/tarry stool or blood in stool/vomit, yellow gums/eyes, severe weakness, wobbliness/incoordination, or seizures. If any of these urgent signs are reported, treat as an emergency and connect the owner with a veterinarian or direct them to the nearest emergency clinic immediately. Your veterinarian can advise on next steps and whether medication changes are appropriate.
Front desk script: Thanks for calling—some cats on Onsior can have mild stomach upset or be a little sleepy after surgery. I want to ask a few quick questions about vomiting, stool, appetite, and any changes in drinking or peeing so I can update the veterinarian. If you’re seeing black or bloody stool, blood in vomit, yellow gums/eyes, repeated vomiting/diarrhea, severe lethargy, wobbliness, or seizures, this is urgent—I’m alerting a veterinarian now; if we get disconnected, please head to the nearest emergency clinic. Your veterinarian will advise you on the safest next steps.
Forms: Onsior is a prescription NSAID for cats. It’s usually sent home as a small flavored tablet; some cats also receive an injection at the clinic. Give exactly as labeled. Tablets must be given whole—do not split, crush, or chew. They can be given with or without food; a small bite or treat right after is okay. Avoid hiding it in a large meal because that can reduce how much medicine is absorbed.
Pilling tips: Try a pill pocket or a pea-sized amount of soft food, place the tablet on the back of the tongue, then offer a sip of water or a small treat to help it go down. If your cat spits out or chews the tablet, or you aren’t sure it was swallowed, call the clinic before giving another. If pilling is difficult, your veterinarian can demonstrate techniques or discuss tools (e.g., a pill dispenser).
Troubleshooting and when to escalate: If your cat vomits after a dose, call the clinic for next steps—do not give an extra dose unless the veterinarian instructs you to. Seek same‑day care immediately if you see repeated vomiting, black/tarry stool, blood in vomit or stool, not eating, marked lethargy, yellow gums/eyes, or notable changes in drinking or urination. If your cat absolutely won’t take tablets, your veterinarian can discuss using a reputable compounding pharmacy to make a flavored liquid; note that compounded products are not FDA‑approved and should be used only if the veterinarian prescribes them.
Front desk script: Onsior tablets can be given with or without food—giving a small treat right after is fine, but please don’t crush or split the tablet. If pilling is hard, we can show you some tricks or the doctor can discuss other options, including a compounded liquid if appropriate. If your cat vomits after a dose or spits the pill out, please call us before giving another. If you notice black or bloody stool, repeated vomiting, yellow gums/eyes, or unusual lethargy, contact us or the nearest emergency clinic right away.
Robenacoxib (Onsior) for cats is an Rx-only NSAID labeled for short-term use to control pain and inflammation after surgery, with a maximum labeled course of three days. Because of this limited duration, refills are uncommon and must be approved by the veterinarian; the doctor will decide if a re-exam is needed before authorizing any additional course or brand/generic changes. Onsior should not be used together with other NSAIDs or corticosteroids, and the manufacturer notes the tablets should not be split; questions about repeat courses or administration must be deferred to the veterinarian. ([my.elanco.com](https://my.elanco.com/us/onsior))
As of January 9, 2026, FDA has also approved the first generic robenacoxib tablets for cats; they are prescription-only and labeled for up to three days of postoperative use, similar to Onsior. If a caller requests a specific brand or a generic, document the preference and defer substitution decisions to the veterinarian (use “dispense as written” if directed). ([fda.gov](https://www.fda.gov/animal-veterinary/cvm-updates/fda-approves-first-generic-robenacoxib-tablet-postoperative-pain-inflammation-cats?utm_source=openai))
Refill call checklist: confirm patient and owner info, surgery/procedure date, reason for use, remaining doses, last dose given, current medications (especially any NSAID or steroid), and any concerning signs (vomiting, diarrhea or black/tarry stool, poor appetite, marked lethargy, yellow gums/eyes). Capture pharmacy preference (in-clinic pickup vs. licensed external pharmacy) and contact details. Typical turnaround is within 1 business day for routine requests; same-day routing is recommended if the cat is post-op and out of doses. Escalate immediately to a veterinarian if red-flag signs are reported; if severe signs are described (bloody vomit/black stool, yellow gums, collapse, seizures), direct the caller to seek emergency veterinary care now. Your veterinarian can discuss whether a recheck is needed and the most appropriate pain-control plan. ([vcahospitals.com](https://vcahospitals.com/roberts/know-your-pet/robenacoxib?utm_source=openai))
Front desk script: “Thanks for calling about a robenacoxib (Onsior) refill. This medication is typically used just for the first three days after surgery, so refills need doctor review. I’ll collect a few details—when surgery was, how many doses are left, any other meds your cat is on, and which pharmacy you prefer—and I’ll send this to the veterinarian today. If you’re seeing vomiting, black/tarry stool, yellow gums, severe lethargy, or your cat received another pain medicine or a steroid, I’m going to alert the doctor right away; if those signs are severe, please go to the nearest emergency clinic now. The doctor will advise next steps and whether a recheck is needed.”
Escalate to a veterinarian or veterinary technician immediately if a client reports any of the following while a cat is on robenacoxib (Onsior): repeated or severe vomiting or diarrhea; blood in vomit or stool; black, tarry stool; not eating; marked lethargy/weakness, wobbliness, collapse, or seizures; yellow gums/skin/eyes (jaundice); sudden changes in drinking or urination (much more or much less), or inability to urinate; unusual bruising or bleeding (including increased bleeding from a recent incision). These can indicate serious NSAID side effects affecting the stomach/intestines, kidneys, or liver, and can become life‑threatening quickly.
Also treat as an emergency if there are signs of a severe allergic reaction (facial swelling, hives, intense itching, or trouble breathing) or if an overdose is suspected (extra tablets chewed, multiple doses taken, or use with another NSAID or a steroid). The FDA and manufacturer advise contacting a veterinarian immediately if side effects are suspected; your veterinarian can discuss risks and next steps for that specific patient.
Front desk script: Based on what you’re describing, this could be a serious reaction to Onsior. Please stay on the line—I’m getting our veterinarian or a technician right now. If your cat has facial swelling, trouble breathing, black/tarry stool, collapses, or you think extra tablets were eaten, this is an emergency—head to the nearest emergency vet if we get disconnected. The veterinarian will advise you on exactly what to do next.
Robenacoxib (Onsior) is a prescription NSAID for cats. Front desk should immediately flag if an owner reports the cat is also getting any anti‑inflammatory pain medicine or any steroid (for example, meloxicam, aspirin/baby aspirin, prednisolone, budesonide, or a recent Depo‑Medrol injection). Combining these increases the risk of stomach/intestinal bleeding and kidney problems; your veterinarian can discuss if a washout or alternative is needed.
Other medication categories to flag: heart/kidney drugs that can change kidney blood flow (ACE inhibitors like benazepril/enalapril; diuretics like furosemide) because extra monitoring may be needed; medicines that can affect heart rhythm (QT‑prolonging drugs such as cisapride, some antihistamines, and certain anesthetics) — let the team know before any procedure; and highly protein‑bound or immunosuppressive/behavior meds (for example, cyclosporine; fluoxetine or clomipramine) where vets may want to monitor for side effects. Evidence in healthy cats suggests benazepril used with robenacoxib can be tolerated, but decisions for individual patients must be made by the veterinarian.
Common OTC human items owners may give alongside — all should trigger a handoff to the veterinarian: aspirin/baby aspirin or combo cold products, ibuprofen or naproxen, acetaminophen (Tylenol; dangerous to cats), antihistamines, antacids (famotidine/cimetidine), fish oil or herbal/CBD supplements. If the owner reports black/tarry stool, blood in vomit, repeated vomiting, not eating, marked lethargy/weakness, collapse, or much less/much more urine, escalate immediately for urgent veterinary guidance or direct to emergency care.
Front desk script: Thanks for letting us know your cat is on Onsior and also taking [owner’s medication]. Because some medicines can interact with Onsior, I’m going to flag this for our veterinarian to review right away and we’ll call you back with guidance today. Before we connect you, has your cat had any black or bloody stools, repeated vomiting, not eating, severe weakness, or collapse? If yes — please head to the nearest emergency clinic now while I alert the doctor. If any human pain reliever like aspirin, ibuprofen, naproxen, or acetaminophen was given, please tell me so I can prioritize this for the veterinarian.
For owner-dispensed Onsior (robenacoxib) tablets for cats: store at controlled room temperature, 59–77°F (15–25°C). Keep tablets dry and away from heat and humidity (avoid bathrooms and sunny windowsills). Because the tablets are flavored, store them in a childproof, pet‑proof location (ideally a closed, high cabinet or locked drawer). Do not use past the package expiration date. Your veterinarian can discuss any special storage considerations for your patient.
Front-desk dispensing reminders: provide the manufacturer’s dispensing envelope with the “Information for Cat Owners” sheet intact; do not remove it. Do not suggest splitting or crushing tablets; they are intended to be given as whole tablets. If clients have questions about missed or vomited doses or timing relative to surgery, defer to the veterinarian.
Disposal: do not flush NSAIDs. Encourage take‑back programs or mail‑back envelopes when available. If no take‑back option exists, mix unused tablets with an unpalatable material (used coffee grounds or cat litter), seal in a bag or container, and place in household trash per FDA/EPA guidance; follow any local regulations. If a child or another pet swallows the medication, or a cat receives more than prescribed, advise the owner to contact the clinic or an emergency veterinary service immediately; for human ingestion, contact Poison Help (1-800-222-1222) right away. Your veterinarian can advise on clinic take‑back or local disposal options.
Clinic-only note (injection kept in hospital): Onsior injection must be refrigerated at 36–46°F (2–8°C) and, once the vial is first punctured, the contents should be used within 12 weeks; clean the vial stopper with isopropyl alcohol at each use.
Onsior (robenacoxib) for cats is an NSAID labeled for short-term use only—up to a maximum of 3 days for postoperative pain. Before starting any NSAID, the veterinarian may request baseline blood and urine testing and will do a history and physical exam. For healthy cats on this 3‑day course, no routine lab recheck is typically needed unless the veterinarian specifies otherwise. Make sure the client leaves with the NSAID Client/Owner Information Sheet and that the pet’s standard post‑surgery recheck with your hospital is on the calendar. ([fda.gov](https://www.fda.gov/animal-veterinary/resources-you/what-veterinarians-should-advise-clients-about-pain-control-and-nonsteroidal-anti-inflammatory-drugs))
Advise owners what to watch for while the cat is taking Onsior and to contact the clinic immediately if they see possible side effects. Concerning signs include vomiting or diarrhea, black/tarry stools, not eating, marked lethargy, yellow gums/eyes, or increased thirst/urination; incoordination or seizures are rare but serious—these warrant urgent contact or emergency care based on the situation. Your veterinarian can discuss any additional monitoring if there are pre‑existing kidney/liver concerns or if an extended pain‑control plan is discussed. ([fda.report](https://fda.report/DailyMed/f4f307a0-88b5-4740-b198-35edef954bf1))
Front desk script: I’ll confirm whether baseline blood and urine tests are already on file or if the doctor wants them before starting the Onsior, and I’ll book your cat’s routine post‑surgery recheck. While your cat is on this 3‑day medication, please call us right away if you notice vomiting, diarrhea, black stools, not eating, yellow gums/eyes, unusual sleepiness, or big changes in drinking or urination. If your cat collapses, has trouble breathing, or has a seizure, go to the nearest emergency clinic now. The veterinarian will let you know if any follow‑up bloodwork is needed.
Onsior (robenacoxib) is a prescription NSAID for cats used short‑term after spay/neuter or orthopedic surgery to help with pain and inflammation. It’s for cats only, and is labeled for use for a maximum of three days. It should not be combined with other anti‑inflammatory medicines like NSAIDs or steroids; any medication timing or compatibility questions should be directed to the veterinarian.
If a caller reports red‑flag signs while a cat is on Onsior, treat it as urgent: vomiting or diarrhea, not wanting to eat, black/tarry stool or blood in vomit/stool, marked lethargy, yellow gums/eyes, big changes in drinking or urination, incoordination, seizures, or unusual behavior. Escalate immediately to a veterinarian; if there is trouble breathing, facial swelling, or collapse, direct the caller to an emergency clinic now. Phrases to avoid: “It’s fine to give with other pain meds,” “Just keep giving it until it’s gone,” “You can start/stop it on your own,” or any dosing instructions—those must come from the veterinarian.
Front desk script: Thanks for calling [Clinic Name]. Onsior is a prescription anti‑inflammatory for cats used short‑term after surgery; I can get your cat’s chart pulled up and have our medical team advise you on your specific questions. If you’re seeing vomiting, black or tarry stool, yellow gums/eyes, your cat is very lethargic, or drinking/peeing much more or less, please stay on the line—I’m paging a veterinarian now; if there’s trouble breathing, facial swelling, or collapse, please head to the nearest emergency clinic immediately. I’ll transfer you to a nurse/doctor so your veterinarian can review next steps and scheduling. Do you prefer a same‑day call back or to book a tech consult?