Onsior Tablets, 6 mg
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Small, flavored tablets for post-surgical pain with once-daily dosing for a maximum of 3 days
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For pain relief following orthopedic surgery and spay /neuter.
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Help get them from hospital to home comfortably
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The only FDA-approved oral NSAID for cats
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Onsior is available by prescription only. Talk to your veterinarian to find out if Onsior is right for your cat.
INDICATIONS:
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.
IMPORTANT SAFETY INFORMATION:
ONSIOR tablets for cats should only be given to cats. People should not take ONSIOR tablets. Keep ONSIOR tablets and all medication out of reach of children. Do not use in cats less than 5.5 lbs. or less than 4 months of age. Do not give ONSIOR if your cat has had an allergic reaction (such as hives, facial swelling, or red or itchy skin) to robenacoxib (the active ingredient in ONSIOR) or to aspirin or other non-steroidal anti-inflammatory drugs (NSAIDs). Do not give Onsior with other NSAIDs (e.g., aspirin, meloxicam) or corticosteroids (e.g., prednisone). ONSIOR tablets should only be given once a day and for no longer than 3 days. ONSIOR tablets may cause some side effects in individual cats. These are normally mild, but serious side effects have been reported in cats taking NSAIDs including ONSIOR tablets. Serious side effects can result in death. It is important to stop the medication and contact your veterinarian immediately if your cat appears to be uncomfortable. Possible side effects are decreased appetite, vomiting, diarrhea, changed stool color, change in drinking or urination, behavioral changes such as depression or restlessness. For complete safety information, please see ONSIOR
product label or ask your veterinarian.
Product sourced directly from the manufacturer or their approved distributor. Guaranteed genuine product backed by the manufacturer.
For
Cats
Active ingredient(s)
Robenacoxib
Drug class
Nonsteroidal anti-inflammatory drug (NSAID)
Product flavoring
Onsior tablets are yeast flavored.*
*Contains yeast.
Product strength & size
Onsior tablets contain 6 mg of robenacoxib per tablet and are supplied in blister cards containing 3 tablets each. Tablets are not scored and should not be broken.
Please ensure the selected product and quantity are appropriate for your pet, as recommended by your veterinarian. For current availability, please refer to the product selection above.
Usage
Onsior should be administered as directed by your veterinarian. Please consult your veterinarian before making any changes or discontinuing the prescribed dosing schedule.
If a dose is missed, administer it as soon as possible. If it is almost time for the next dose, skip the missed dose and continue with the regular schedule. Do not give more medication than prescribed or two doses at once. If you have questions about your pet’s prescribed dosing schedule (e.g., timing, interval), please contact your veterinarian.
Manufacturer Directions for Use*
For pets weighing between 5.5 to 13.2 pounds, give one 6 mg tablet daily or as directed by your veterinarian.
For pets weighing between 13.3 to 26.4 pounds, give two 6 mg tablets daily or as directed by your veterinarian.
*Additional information may be provided within the manufacturer’s full Prescribing Information and the Information for Cat Owners Sheet. Always follow the specific instructions provided by your veterinarian regarding your pet's care.
Storage
Store in a cool, dry place at a controlled room temperature between 59° and 77°F. Keep this and all other medications in a secure location out of the reach of children and animals. Tablets should remain sealed in their original packaging and should only be taken out at the time of dosing.
Exposure to extreme temperatures, light, or moisture can affect the integrity and effectiveness of medications. Always store this medication properly (e.g., away from the bathroom, kitchen sink, or other damp places).
Side effects
The most common adverse events are anorexia, depression, vomiting, elevated BUN, elevated creatinine, and renal insufficiency/failure.
It is important to stop the medication and contact your veterinarian immediately if you think your cat may have a medical problem or is experiencing side effects while on Onsior tablets. Monitor for the following side effects that may indicate your cat is having a problem:
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Vomiting, particularly if severe, appears bloody, or has a “coffee grounds” appearance
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Significant decrease or complete loss of appetite
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Extreme changes in behavior, such as depression or restlessness
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Change in bowel movements, such as (severe) diarrhea or changes in stool color (e.g., dark or tarry stools)
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Significant changes in drinking or urination
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Yellowing of gums, skin, or whites of the eyes (jaundice)
The information provided above may not encompass all possible side effects. Please notify your veterinarian if your pet experiences any side effects, including those listed above, or if you notice anything unusual.
Precautions
Before using this product, please review the manufacturer’s full Prescribing Information and the Information for Cat Owners Sheet for any relevant warnings and safety precautions.
For oral use in cats only.
Not for use in humans. Keep this and all other medications out of reach of children and animals. Consult a physician in case of accidental ingestion by humans.
Do NOT administer Onsior to cats with a preexisting liver or kidney condition or those that have any condition predisposing to dehydration (e.g., active infection, taking a diuretic).
Robenacoxib may prolong the QT interval; the associated risk of developing ventricular arrhythmia is unknown. The use of robenacoxib with other drugs shown to prolong the QT interval is not recommended.
The use of ONSIOR tablets has not been evaluated in breeding, pregnant, or lactating cats. Discuss the risks of using this medication with your veterinarian prior to use if your pet is in one of these groups.
Do not administer this medication to animals with a known or suspected allergy/hypersensitivity to any NSAID, including robenacoxib, or to any other ingredient in the formulation. Allergic reactions to medications may occur. Please inform Vetsource and your veterinarian if your pet has any known sensitivities or allergies, especially to medications and supplements.
If your pet displays symptoms of an allergic reaction, discontinue therapy and call your veterinarian immediately or seek emergency veterinary attention. Symptoms may include (but are not limited to): swollen lips, tongue, face, or airways; difficulty breathing; agitation; profuse salivation; and widespread hives or itching.
Food and drug interactions
Do NOT administer Onsior tablets in conjunction with any other oral or injectable NSAID or corticosteroid.
The following drugs* may have potential interactions with this medication:
ACE inhibitors (e.g., benazepril), amlodipine, anticoagulants (e.g., warfarin), antidiabetic agents (including insulins), aspirin, beta blockers (e.g., atenolol, sotalol), clopidogrel, corticosteroids (e.g., dexamethasone, prednisolone), cyclosporine, digoxin, diuretics (e.g., furosemide, spironolactone), fluconazole, fluoroquinolone antibiotics (e.g., ciprofloxacin), methotrexate, concurrent NSAIDs, pentoxifylline, sildenafil, SSRIs (e.g., fluoxetine), telmisartan (Semintra), toceranib (Palladia), and tricyclic antidepressants (e.g., amitriptyline).
*NOTE: This may not be a comprehensive list. As with all medications, please consult your veterinarian if you have any questions or concerns prior to use. Contact your veterinarian if your pet experiences any unusual reactions when multiple medications and/or supplements are given together.
Please ensure your veterinarian is aware of all medications, supplements, and over-the-counter (OTC) products that your pet is currently using. Your veterinarian may prescribe multiple medications, even if a potential drug interaction may occur. In these instances, your veterinarian may adjust the dosages or monitor your pet more closely.
Adverse reactions
If you are concerned that your pet has experienced an adverse reaction to this medication, please contact Elanco at 1-888-545-5973 or Vetsource Pet Owner Care at 877-738-4443.
Overdose
If you have any reason to suspect accidental ingestion or overdose, call your doctor/veterinarian or the appropriate poison control resource immediately.
For humans:
The national toll-free Poison Help line, 1-800-222-1222, will connect you to your local poison center in case of emergency. This service is available nationwide and in most U.S. territories.
For animals:
The ASPCA Animal Poison Control Center is available 24 hours a day, 365 days a year at 888-426-4435.
Pet Poison Helpline also provides a 24/7 animal poison control service at 855-764-7661.
*Please note: The contact information provided above is for third-party services in the event of a potential poison-related emergency. Consultation fees may apply for these services.
Disclaimer
The content provided on this page is NOT medical advice.
All content, including the images and product description above, is intended for general informational purposes only and should not be considered a substitute for professional veterinary consultation, diagnosis, or treatment.
For additional information about this product and how it fits into your pet's individual treatment plan, please consult your veterinarian.
Last revised: 6/30/2026