What’s actually slowing this PC down?
Pick the symptom - the matching free tool is one click away.
Robenacoxib is a prescription anti-inflammatory tablet for cats. In the United States, the Onsior tablet label covers control of postoperative pain and inflammation after orthopedic surgery, ovariohysterectomy (spay) and castration. It is labeled for cats at least four months old and at least 5.5 lb (2.5 kg), at 1 mg/kg (0.45 mg/lb) by mouth once daily, for no more than three days. Anything beyond that, or any use outside those indications, is a decision for the prescribing veterinarian.
This guide reflects U.S. labeling and U.S. Food and Drug Administration (FDA) guidance as checked on October 9, 2026. Doses, approvals and product availability differ in other countries and can change, so confirm them with a local veterinarian or regulator.
What robenacoxib is
Robenacoxib belongs to the coxib class of nonsteroidal anti-inflammatory drugs (NSAIDs). Like other NSAIDs, it reduces inflammation and pain, but it is not a sedative and does not treat the underlying cause of a problem. It is sold under the brand name Onsior in the United States, and tablets are prescription-only, so a licensed veterinarian must authorize them.
What the U.S. label covers
The FDA-approved tablet indications are narrow: postoperative pain and inflammation associated with three procedures, namely orthopedic surgery, ovariohysterectomy and castration. The label does not establish that robenacoxib is approved in the U.S. for every cause of feline pain, such as arthritis flares, dental pain or injury. Using it for those purposes is an off-label decision that belongs to the veterinarian, who may weigh other options.
#1 Best Overall
- SOOTHE WHOLE BODY HOMEOPATHY - Manage your besties pain naturally with the power of Arnica plus medicines like Calendula, Echinacea and Hypericum to support their healing process, calming minor discomfort in muscles, joints, and hips, as well as soreness and pain due to injuries
- PLANT-BASED CARE TO THE RESCUE - Lasting relief of aches and pains helps your furry friend get back to doing what they love; gentle formula can be used with your pet's daily supplement, vitamins, or medication without known interaction.
- BOOST THEIR BODY'S DEFENSES - Homeopathic remedies help address symptoms with a micro dose of an active ingredient to stimulate the body’s own defenses; we combine multiple potent actives in multiple concentrations for greater relief of more symptoms
- VETS KNOW BEST - Approved by veterinarians, liquid oil remedy can be easily mixed with water or food instead of disguising medicine in treats and chews that pets spit out; dosages provided for dogs, cats, and horses from newborn to adults
- HOLISTIC APPROACH - Natural reliever without risk, a safe non-narcotic alternative with no known interactions or side effects; doesn't just mask pain but goes to its source by supporting their own self-healing mechanisms
Eligibility for tablets
- Age: at least four months old.
- Weight: at least 5.5 lb (2.5 kg).
- Not evaluated in: cats under four months, cats under 5.5 lb, cats used for breeding, and pregnant or lactating cats.
- Contraindicated in: cats with known hypersensitivity to robenacoxib or known intolerance to NSAIDs.
Dosage and duration
The labeled dose is 0.45 mg/lb (1 mg/kg) by mouth once daily, with a maximum of three days of treatment. The label directs use of the lowest effective dose for the shortest duration consistent with the individual cat’s response. The tablet chart works in whole tablets, and the 6 mg tablets are not scored and should not be broken.
| Cat’s weight (U.S. label chart) | Labeled tablet amount, once daily |
|---|---|
| 5.5–13.2 lb (2.5–6 kg) | One 6 mg tablet |
| 13.3–26.4 lb (6.1–12 kg) | Two whole 6 mg tablets |
These figures are the printed label directions, not a calculation for your cat. Cats outside the weight bands in this chart need veterinary direction, and owners should never split a tablet to fit a dose.
Rank #2
- NATURAL ANTIBIOTICS FOR CATS: Formulated with a blend of beneficial and completely safe extracts from plant pomace, this ensures that your cat gets the most critical components with no harm to its body.
- GENTLE AND COMPREHENSIVE CARE: Drawing on the power of nature, our Antibiotic for cats composition helps with everyday moments in cats, including allergies, UTIs, and more.
- NATURE'S ANSWER TO CHEMICALS: Qualified experts precisely measure each ingredient of cat Antibiotics in liquid form to ensure it delivers maximum benefit while remaining completely safe for pets.
- FOR CATS OF ALL BREEDS: This non-toxic supplement was developed with guidance from a specialist to ensure proper digestion. The liquid quickly enters the circulation and has a supportive effect.
- PROVIDING NATURAL BALANCE: Our natural Antibiotic for cats and all supplements undergo strict laboratory testing before being approved for sale. Products are both practical and safe for your pet.
Before the first dose
The label requires a veterinary history and physical examination before NSAID therapy, plus appropriate laboratory tests to establish hematological and serum biochemical baseline data. Dehydrated cats, cats on diuretics, and cats with existing kidney, heart or liver dysfunction may face a higher risk of adverse events. The label recommends perioperative fluid therapy when an NSAID is used, to reduce the risk of kidney complications. Whether your cat has any of these conditions is for the veterinary team to establish, not for an owner to infer from symptoms at home.
Side effects and what to do
The owner information in the U.S. tablet label lists these signs of possible intolerance:
Quick wins for a faster PC:
Scan for outdated or missing drivers - takes under a minuteDriver Scan →Repair Windows errors before they cause bigger problemsFix Now →Fix the driver behind crashes, sound loss and screen glitchesFind Drivers →Rank #3
- Expert-formulated homeopathic support - Crafted by pet wellness experts, this homeopathic formula includes Arnica montana, Bryonia, Rhus tox, and Belladonna to help maintain healthy mobility and natural ease of movement in dogs and cats.
- Supports Joint Function & Flexibility—Formulated to promote healthy joint mobility and flexibility in pets of all ages. A great addition to your pet’s routine for maintaining ease of movement.
- For Dogs & Cats of All Ages – Whether your pup is slowing down or your cat enjoys staying active, this liquid supplement supports ongoing comfort and vitality for pets young and old.
- Gentle and alcohol-free formula - Made with non-addictive, preservative-free ingredients in a liquid base that contains no alcohol—suitable for pets of all sizes and sensitivities.
- USA Made with Trusted Quality – Our formula is made in the United States using thoughtfully sourced ingredients. ComfyPet Pain Relief offers simple, homeopathic support for everyday pet wellness.
- Vomiting or diarrhea
- Decreased appetite
- Dark or tarry stools
- Increased water consumption or increased urination
- Signs of anemia
- Yellowing of the gums, skin or whites of the eyes (jaundice)
- Lethargy or incoordination
- Seizures or behavioral changes
If any of these appear, stop the tablets and contact the veterinarian immediately. The label also says to stop if appetite drops or the cat becomes lethargic. Do not wait to see whether the sign passes.
Medicines to avoid combining
Do not give Onsior tablets or injection together with another oral or injectable NSAID, or with a corticosteroid. Tell the veterinarian about every medication, supplement and prescription the cat already takes before the first dose, because the combination risk applies to other anti-inflammatory drugs as well.
Rank #4
- VETERINARIAN RECOMMENDED COMFORT: Ensure maximum mobility, longevity, and joint support for your cat with Summit Animal Health Joint & Mobility for Feline Joint Relief. Perfect for both young and senior felines in need of total body inflammation relief.
- FIGHT JOINT PAIN + DEGENERATION: Target hip, back, and elbow pain, especially the effects of arthritis. Our supplement not only repairs wear and tear but also addresses the root causes of joint discomfort, ensuring optimal feline health.*
- NATURALLY MANAGE CHRONIC PAIN + INFLAMMATION: This anti-inflammatory solution isn’t just for joints. Its potent antioxidant properties combat destructive enzymes, offering pain relief and reducing soreness and swelling at the cellular level - a must-have for every cat owner.*
- PATENTED LIPOSOMAL DELIVERY: With our patented technology developed by renowned scientist Dr Marvin S. Hausman, Summit Animal Healths Joint & Mobility Feline Relief Solution ensures maximum absorption. Unlike most supplements where ingredients degrade, ours delivers unrivaled, effective results. A leap beyond both traditional prescription and non-prescription medications.*
- UNIQUE FORMULA. UNRIVALED RESULTS: 100% natural, drug-free, and without CBD. Our powerful pharmaceutical-grade chondroitin 4-sulfate formulation offers unrivaled joint repair benefits without needing aspirin or pain masking medications. A superior anti-inflammatory relief medication. A superior anti-inflammatory relief medication. In one tasty, weekly dose, Joint & Mobility Feline Relief Solution is the supplement all cats love.*
Limits on repeating or extending treatment
FDA consumer guidance on pain relievers for pets states that more than three doses of robenacoxib in cats have not been shown to be safe. Do not prolong, restart or adjust a course because the cat seems to be in pain or seems better. Any further treatment needs a new veterinary assessment.
Tablets and the injection are different products
Onsior also has an injectable form, given by a veterinary team under its own label. The injection is not interchangeable with the tablets on a milligram-for-milligram or dose-for-dose basis, and it has its own labeled dose. The injection label times the first dose before surgery, and in eligible cats later doses may be given as tablets, within a total maximum of three doses over three days. Those timing and switching decisions belong to the veterinary team.
Do these 3 things before closing this tab:
1Clear out junk files and repair common Windows errors2Fix the driver behind crashes, sound loss and screen glitches3Repair Windows errors before they cause bigger problemsBest Value
- HEALING AID AND SKIN REPAIR: Use a few times daily to flush and decontaminate your cat's wounds, cuts, abrasions, sores, and irritations.
- CAT FIRST-AID ESSENTIAL: Works great on every feline species at any life stage to relieve skin problems
- SAFE & EFFECTIVE: Made with a non-toxic hypochlorous technology that is pH-balanced and safe if licked or ingested
- VETERINARIAN RECOMMENDED: Support wound healing with this anxiety-free, cost-effective alternative to antibiotic or steroid ointments.
- TRUSTED BRAND: Vetericyn is a leader in at-home animal health products manufactured to help cat owners take the best care of their pets.
Generic robenacoxib
On January 9, 2026, the FDA announced approval of the first generic robenacoxib tablet for the same postoperative indications in cats at least four months old and 5.5 lb. The FDA says the generic contains the same active ingredient as Onsior, is bioequivalent to the brand-name product, is prescription-only, and may be given for up to three days. The sponsor named in that notice is ZyVet Animal Health, Inc. On March 9, 2026, the FDA announced approval of the first generic robenacoxib injectable product for postoperative pain and inflammation in dogs and cats.
Where the evidence stops
The official sources reviewed here establish labeled doses, eligibility, warnings and approval status. They do not provide an effectiveness percentage or an adverse-event rate for cats, so this article makes no such claim. Ask your veterinarian about the expected response and what monitoring to plan for your cat’s procedure or condition.
Quick Recap
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon at the time of purchase will apply.
