Carprofen and Rimadyl are the same medication. Rimadyl is simply the brand name for the generic drug carprofen, much like how Advil is the brand name for ibuprofen. Rimadyl was the first version brought to market by Zoetis (formerly Pfizer Animal Health), and several generic versions have followed since.
Brand Name vs. Generic Versions
Rimadyl was the original FDA-approved brand of carprofen for dogs. Today, generic carprofen is also sold under names like Vetprofen, Novox, and simply “Carprofen Caplets” or “Carprofen Chewable Tablets.” All contain the same active ingredient at the same strengths, typically available in 25 mg, 75 mg, and 100 mg tablets.
To earn FDA approval, generic versions must prove they are bioequivalent to Rimadyl. That means the drug reaches the same concentration in the bloodstream at roughly the same speed. FDA testing of generic carprofen chewable tablets showed the peak blood levels and total drug absorption fell well within the required equivalence range compared to Rimadyl. Because of this, the FDA did not require separate effectiveness or safety studies for the generics. In practical terms, your dog’s body processes brand-name Rimadyl and generic carprofen identically.
The main difference is price. Generic carprofen is often cheaper, which matters for dogs that take it daily over months or years. Your vet may prescribe either one, and pharmacies can sometimes substitute the generic unless the prescription specifies otherwise.
What Carprofen Does
Carprofen is a nonsteroidal anti-inflammatory drug (NSAID) designed for dogs. It is FDA-approved for two specific uses: relieving pain and inflammation from osteoarthritis, and controlling pain after soft tissue or orthopedic surgeries.
It works by blocking an enzyme called COX-2, which produces the chemicals responsible for inflammation and pain. Dogs also have a related enzyme, COX-1, that protects the stomach lining and supports kidney function. In laboratory studies using canine cells, carprofen showed a preference for blocking COX-2 over COX-1, which is part of why it tends to be easier on the stomach than older anti-inflammatory drugs. That said, it doesn’t completely spare COX-1, which is why gastrointestinal side effects can still occur.
Standard Dosing
The recommended dose is 2 mg per pound of body weight per day. This can be given as a single daily dose or split into two doses of 1 mg per pound, morning and evening. A 50-pound dog, for example, would typically get 100 mg total per day. Your vet will determine the right schedule based on your dog’s condition, size, and overall health.
Side Effects and Warning Signs
Most dogs tolerate carprofen well. Serious side effects occur in fewer than 1% of dogs, but when they happen, they can be severe. The most common mild reactions involve the digestive system: vomiting, diarrhea, decreased appetite, or constipation.
The rare but serious reactions involve the liver, kidneys, or gastrointestinal tract. Watch for these warning signs:
- Digestive problems: vomiting, black or bloody stools, or persistent diarrhea
- Liver damage: yellowing of the gums, skin, or whites of the eyes
- Kidney issues: changes in how much your dog drinks or urinates
- General decline: severe lethargy, loss of appetite lasting more than a day, disorientation, or seizures
These serious reactions can appear without warning, which is why vets recommend periodic blood work for dogs on long-term carprofen. Blood tests check liver enzymes and kidney values to catch problems before symptoms become obvious. Dogs with pre-existing liver, kidney, or heart disease face a higher risk and may not be good candidates for this medication.
Drugs to Avoid Combining With Carprofen
Carprofen should never be given alongside another NSAID. Combining two anti-inflammatories of the same class dramatically increases the risk of stomach ulcers, kidney damage, and abnormal bleeding. This includes both prescription veterinary NSAIDs and over-the-counter human medications like ibuprofen or aspirin.
Corticosteroids such as prednisone or dexamethasone are also a dangerous combination. The overlap in how these drugs affect the stomach and kidneys creates a compounding risk. If your dog is switching between a steroid and carprofen, your vet will typically require a washout period of several days between the two.
Carprofen Is Not Safe for Cats
All versions of carprofen, whether Rimadyl or generic, are labeled for dogs only in the United States. Cats metabolize the drug much more slowly, giving it an elimination half-life roughly four to five times longer than in dogs. This means the drug builds up in a cat’s system far more quickly, creating a much narrower margin of safety. Even a single 25 mg tablet can be potentially serious in a cat. There have been reported cases of acute kidney failure in cats who ingested carprofen, including one fatality in a kitten at a relatively low dose. If your cat accidentally eats a carprofen tablet, treat it as a veterinary emergency.