Yes, Rimadyl is an NSAID (nonsteroidal anti-inflammatory drug). Its active ingredient, carprofen, belongs to the propionic acid class of NSAIDs, the same chemical family as ibuprofen and naproxen in human medicine. Unlike those drugs, Rimadyl is approved exclusively for use in dogs and should never be given to other pets or people.
What Rimadyl Is Prescribed For
Rimadyl is FDA-approved for two specific uses in dogs: relieving pain and inflammation from osteoarthritis, and controlling pain after soft tissue or orthopedic surgeries. Osteoarthritis is by far the more common reason. Dogs on Rimadyl for arthritis typically take it daily, sometimes for months or years, to manage chronic joint pain and keep them mobile.
How It Works Differently From Other NSAIDs
All NSAIDs reduce pain and inflammation by blocking enzymes called COX-1 and COX-2. COX-2 drives inflammation and pain, while COX-1 helps protect the stomach lining and supports normal kidney function. The problem with older NSAIDs is that they block both enzymes roughly equally, which is why stomach upset and kidney issues are common side effects.
Carprofen stands out because it’s far more selective for COX-2 in dogs. In laboratory testing, carprofen was over 100 times more potent against COX-2 than COX-1 in canine tissue, making it the most COX-2-selective NSAID tested in that study. That selectivity is the main reason it became one of the most widely prescribed pain medications in veterinary medicine. It targets the inflammation pathway while largely sparing the protective one.
Standard Dosing
The FDA-approved dose is 2 mg per pound of body weight once daily, or 1 mg per pound twice daily. Your vet will choose the schedule based on your dog’s condition and how they respond. Rimadyl comes in chewable tablets (flavored, so most dogs take them willingly) and standard caplets.
Side Effects to Watch For
Most dogs tolerate Rimadyl well, but because it’s an NSAID, it carries the same general risks as the drug class. The most common side effects are digestive: decreased appetite, vomiting, and diarrhea. These are usually mild and may resolve on their own or with a dosage adjustment.
Rare but serious reactions can affect the liver or kidneys. Signs of liver trouble include yellowing of the gums, skin, or whites of the eyes (jaundice), along with vomiting and loss of appetite. Kidney-related signs include a sudden increase in thirst and urination, or blood in the urine. Dark or tarry stools suggest bleeding somewhere in the digestive tract. The FDA’s labeling notes that serious reactions can occur without warning, so any of these signs warrant stopping the medication and contacting your vet right away.
Other reported reactions include pale gums (a sign of anemia), lethargy, incoordination, seizures, and behavioral changes. These are uncommon but worth knowing about, especially in the first few weeks of treatment.
Blood Work and Monitoring
Before starting Rimadyl, your vet will likely recommend blood and urine tests to make sure your dog’s liver and kidneys are healthy enough to handle an NSAID. This baseline is important because it gives your vet something to compare against later.
For dogs on long-term Rimadyl for arthritis, periodic blood and urine tests are recommended to catch any organ changes early, before symptoms appear. Your vet will set the schedule based on your dog’s age and overall health, but rechecks every few months are typical for older dogs or those with pre-existing conditions.
Dangerous Drug Combinations
One of the most important things to know about Rimadyl is what not to combine it with. Never give your dog two different NSAIDs at the same time. That includes aspirin, which many owners don’t realize is also an NSAID. Stacking NSAIDs dramatically increases the risk of stomach ulcers, kidney damage, and abnormal bleeding.
Corticosteroids like prednisone and dexamethasone are equally risky to combine with Rimadyl. In reported adverse reactions involving carprofen, 9% of cases involved dogs that were also taking a corticosteroid. If your dog is switching from prednisone to Rimadyl, or from Rimadyl to a different NSAID, a washout period of 5 to 7 days between the two medications is recommended to let the first drug clear the system.
Why It’s Not Used in Cats or People
Carprofen was originally developed for human use and was briefly available in some countries before being withdrawn from the human market. It’s now formulated and approved solely for dogs. Cats metabolize NSAIDs very differently and are far more sensitive to their toxic effects, so Rimadyl is not safe for cats. If your cat needs pain management, entirely different medications are used.