Rimadyl and Carprofen Side Effects in Dogs
Most dogs take carprofen (brand name Rimadyl) without trouble. In the original US field studies, vomiting, diarrhea and reduced appetite occurred at rates similar to dogs given a placebo. The serious problems, such as stomach ulcers and liver or kidney injury, are uncommon but real, and they are most likely in the first weeks of treatment or in dogs with risk factors. This page goes through the signs one by one, what each may mean, and how urgently to act.
- Black, tarry, or bloody stool, or vomit with blood or a coffee-grounds look
- Repeated vomiting, or vomiting with not eating
- Yellow gums, eyes or skin (jaundice)
- Much less drinking or urinating, or a sudden big increase
- Marked weakness, collapse, wobbliness or seizures
- Facial swelling, hives or difficulty breathing
Out of hours, go to the nearest emergency animal hospital. Bring the medication bottle with you.
Carprofen Side Effects, Symptom by Symptom
| What you see | What it may mean | What to do |
|---|---|---|
| Reduced appetite | Common, usually mild stomach irritation. | Give doses with food; tell your vet if it lasts more than a day or two. |
| Vomiting (including yellow bile) | The most common side effect. One episode is usually mild; repeated vomiting, or vomit with blood or a coffee-grounds look, can mean a stomach ulcer. | Stop and call your vet if it happens more than once or there is any blood. |
| Diarrhea or soft stool | Common and usually mild. | Call your vet if it lasts beyond a day or two, or is bloody. |
| Constipation | Uncommon. In the Rimadyl caplet field study it was reported in 0.3% of dogs, the same rate as in dogs given a placebo, so it is often unrelated to the drug. | Keep water available; call your vet if your dog strains without passing stool for more than a day, or the stool is black. |
| Black, tarry stool | Digested blood from bleeding in the stomach or upper gut. Uncommon but serious. | Urgent: stop the drug and call your vet the same day. |
| Drinking and urinating more | Can reflect effects on the kidneys, especially in older dogs or dogs with kidney disease. | Call your vet soon; they will usually check bloodwork. |
| Drinking and urinating much less | Can be a sign of kidney injury, particularly if your dog is also vomiting or dehydrated. | Urgent: call your vet the same day. |
| Lethargy or sleepiness | Carprofen is not a sedative. Some dogs rest more once pain eases, but weakness or dullness can signal a problem. | Call your vet if your dog is weak, unwilling to get up, or not eating. |
| Panting | Not a typical drug effect. Panting more often reflects pain that isn't controlled, heat, anxiety, or another illness. | Mention it to your vet; panting with weakness, pale gums or a swollen belly is an emergency. |
| Itching, hair loss or skin sores | Reported but uncommon: itching, more shedding, hair loss, moist sores, and occasional skin inflammation. | Call your vet; they may switch your dog to a different medicine. |
| Yellow gums, eyes or skin (jaundice) | A sign of liver injury. Rare, but most cases appear in the first few weeks. | Emergency: stop the drug and see a vet the same day. |
| Wobbliness, disorientation or seizures | Rare neurological reactions have been reported. | Emergency: see a vet immediately. |
| Restlessness, agitation or aggression | Rare behavior changes have been reported. | Tell your vet, especially if it started after beginning carprofen. |
| Bruising, nosebleeds or pale gums | Rare blood-related reactions, such as anemia or low platelets. | Urgent: call your vet the same day. |
| Facial swelling, hives, or trouble breathing | Rare allergic-type reaction. | Emergency, especially if breathing is affected. |
| Weight gain | Not a recognised side effect. Dogs often eat better and move less carefully once comfortable, and less activity can add weight. | Adjust food portions; mention steady gain at the next check-up. |
How Common Are Carprofen Side Effects?
Carprofen has been prescribed for dogs in the US since the late 1990s, so its side effects are well documented. In the controlled field studies used for its US approval, the rates of vomiting, diarrhea and appetite changes in treated dogs were close to those in dogs given a placebo. Since approval, the label has listed further reactions reported by owners and vets in four main groups:
- Digestive: vomiting, diarrhea, loss of appetite, black stool, stomach ulcers.
- Liver: raised liver enzymes, jaundice and, rarely, acute liver injury.
- Kidney and urinary: increased thirst and urination, blood in the urine, accidents, and rarely kidney failure.
- Other: skin reactions, behavior changes, neurological signs and blood disorders.
These reports show what can happen, not how often. Because spontaneous reports aren't counted against the number of dogs treated, they can't give a percentage. For most dogs the benefit of controlling arthritis or post-surgical pain outweighs these risks, provided the dog is screened and monitored.
When Side Effects Usually Start
- First few days: stomach upset, if it is going to happen, usually shows early.
- First few weeks: the rare liver reaction (sometimes called idiosyncratic hepatotoxicity) is unpredictable and not dose-related. In the case series that first described it, signs began within roughly 5 to 30 days of starting carprofen, and Labrador Retrievers were over-represented in early reports. Many vets recheck liver values two to four weeks after starting.
- Months to years: on long-term treatment the focus shifts to slow changes in kidney and liver values, which is why dogs on daily carprofen usually have bloodwork every 6 to 12 months, or more often if they have risk factors.
Which Dogs Are at Higher Risk?
- Dogs with kidney, liver or heart disease, or a history of stomach ulcers
- Dehydrated dogs, or dogs having surgery under anesthesia without fluid support
- Dogs also taking a steroid (such as prednisone) or any other NSAID, including aspirin
- Dogs on diuretics (such as furosemide) or ACE inhibitors (such as enalapril or benazepril)
- Senior and giant-breed dogs, whose kidney reserve may be lower
- Dogs that have reacted badly to any NSAID before
None of these automatically rules carprofen out, but each is a reason for your vet to check bloodwork first, use the lowest effective dose, and monitor more closely. See carprofen for dogs with kidney or liver disease and carprofen drug interactions.
Side Effects in Senior and Large Dogs
Older dogs are the main users of carprofen, because arthritis is a disease of age. They are not automatically more sensitive to it, but they are more likely to have early kidney disease or be on other medicines, so pre-treatment bloodwork and regular rechecks matter more. In large and giant breeds, vets often dose on lean body weight to avoid overdosing overweight dogs. See carprofen for senior dogs.
How to Treat Rimadyl (Carprofen) Side Effects
Rimadyl side effects are treated by holding the next dose, calling your vet, and treating the specific problem. Mild stomach upset is often managed by giving doses with food or pausing for a day or two. Black stool, repeated vomiting, jaundice or changes in drinking need an exam and bloodwork the same day. Most dogs with a mild reaction recover fully once the drug is stopped.
What to do at home, right away
- Hold the next dose until you have spoken to your vet. Don't give a "make-up" dose later.
- Call your vet and describe exactly what you see, when it started and how many doses your dog has had. Out of hours, call an emergency animal hospital.
- Keep fresh water available and offer a small, bland meal only if your vet agrees.
- Don't give human remedies. Pepto-Bismol contains bismuth subsalicylate, an aspirin relative, which adds to the ulcer risk of an NSAID. Never give ibuprofen, naproxen or aspirin for the pain instead (see why ibuprofen is dangerous for dogs). Antacids such as famotidine or omeprazole are used by vets, but only at a dose they set.
- Take the bottle with you if your dog is seen, so the vet knows the brand, strength and how many tablets are left.
What the vet usually does, by problem
| Problem | How urgent | Typical treatment |
|---|---|---|
| One episode of vomiting or soft stool | Call within a day | Give doses with food, pause for a day or two, or lower the dose; sometimes a stomach protectant. |
| Repeated vomiting, black or bloody stool (possible ulcer) | Same day | Stop carprofen; stomach protectants such as omeprazole, famotidine or sucralfate; fluids; bloodwork to check for blood loss. Severe bleeding may need hospital care. |
| Drinking or urinating much more or less (kidney stress) | Same day | Stop carprofen; kidney bloodwork and a urine test; intravenous or under-the-skin fluids. |
| Yellow gums, eyes or skin (liver reaction) | Emergency | Stop carprofen permanently; liver bloodwork; supportive care, sometimes in hospital; repeat bloodwork until values return to normal. |
| Itching or skin sores | Call within a day or two | Usually a switch to a different pain medicine, plus skin treatment if needed. |
| Seizures, collapse, facial swelling or trouble breathing | Emergency | Immediate emergency care. |
After a reaction, many dogs are managed with a different type of pain relief, such as Galliprant, gabapentin or Librela (see carprofen alternatives). A dog that had a liver reaction to one brand of carprofen should not be given another brand, because Rimadyl, Novox, Vetprofen, Carprovet and the other generics are all the same drug. Your vet can report the reaction to the manufacturer and the FDA.
How Long Do Rimadyl Side Effects Last?
Mild stomach upset from Rimadyl usually settles within one to three days of stopping the drug. Carprofen has a half-life of about 8 hours in dogs, so most of it has left the body within two days. Ulcers, liver injury and kidney injury are different: they are damage that has to heal, so recovery takes days to weeks and depends on how severe it was and how quickly it was treated.
- Vomiting, soft stool, reduced appetite: usually better within 1 to 3 days of the last dose.
- Sleepiness or quietness: should lift within a day or two; if it doesn't, something else may be going on.
- Stomach ulcer: typically several weeks of stomach protectants.
- Liver reaction: liver values often take weeks to return to normal; your vet will repeat bloodwork.
- Kidney injury: varies widely; some dogs recover fully, others are left with reduced kidney function.
If a sign is getting worse rather than better after stopping, or hasn't improved within two to three days, call your vet again rather than waiting.
Reducing the Risk
- Ask for bloodwork before starting, and again a few weeks in if your dog will be on it long-term.
- Give every dose with a meal, and keep fresh water available.
- Never combine carprofen with aspirin, ibuprofen, another NSAID or a steroid unless your vet plans it.
- Keep to the prescribed dose and schedule, and don't double up after a missed dose.
- Watch stool colour, appetite and thirst for the first month.
- Report suspected side effects to your vet, who can report them to the manufacturer and the FDA.
Long-Term Use
Many dogs take carprofen for years. The long-term concerns are gradual changes in kidney and liver values, so most vets recommend bloodwork (and often a urine test) every 6 to 12 months, more often for older dogs or those with risk factors. See carprofen bloodwork monitoring and how long a dog can stay on carprofen.
Expired Tablets
Expired carprofen is more likely to have lost strength than to have become harmful, but there is no guarantee. Ask your vet or pharmacist before using tablets past their expiry date. See our storage and expiration guide.
Frequently Asked Questions
What are the most common carprofen side effects in dogs?
Vomiting, soft stool or diarrhea, and reduced appetite are the most common, usually in the first days or weeks of treatment. In the original US field studies these occurred at rates similar to dogs given a placebo.
Are Rimadyl side effects different from carprofen side effects?
No. Rimadyl is a brand of carprofen, so Rimadyl, Novox, Vetprofen, Carprovet and the other generics share the same side-effect profile.
How soon do carprofen side effects start?
Stomach upset usually shows within the first few days. Liver reactions are rare, and most reported cases began within the first few weeks (roughly 5 to 30 days) of starting the drug, which is why vets often recheck bloodwork two to four weeks in.
Does Rimadyl cause drowsiness?
Rimadyl (carprofen) is not a sedative, but lethargy is a reported side effect. Many dogs simply rest more once their pain is controlled. True dullness, weakness or not wanting to get up is a warning sign to report to your vet. See does carprofen make dogs sleepy?
Can carprofen cause constipation in dogs?
It can, but it is uncommon. In the Rimadyl caplet field study, constipation was reported in 0.3% of treated dogs, the same rate seen with a placebo. Straining with no stool for more than a day, or black stool, needs a call to your vet.
Can carprofen cause panting in dogs?
Panting is not a typical carprofen side effect. It more often points to pain that is not fully controlled, heat, anxiety or another illness. Mention it to your vet, and treat panting with weakness or pale gums as an emergency.
Can carprofen cause itching in dogs?
Yes, uncommonly. Itching, hair loss and skin sores are listed among reported reactions. Tell your vet, who may switch to a different pain medicine.
Can carprofen cause kidney or liver damage?
Rarely, yes. Dogs that are dehydrated, older, or already have kidney or liver disease are at higher risk. Baseline and periodic bloodwork helps catch problems early.
Can carprofen cause seizures?
Seizures and other neurological signs have been reported very rarely. Any seizure needs immediate veterinary attention.
Sources & Further Reading
- Rimadyl (carprofen) US package insert (Zoetis), adverse reactions and post-approval experience
- Rimadyl Caplets dog owner information and field study adverse reactions (Zoetis; Animal Drugs @ FDA)
- FDA Center for Veterinary Medicine, Freedom of Information Summary for carprofen (NADA 141-053)
- MacPhail CM et al. Hepatocellular toxicosis associated with administration of carprofen in 21 dogs. J Am Vet Med Assoc. 1998;212(12):1895-1901
- Plumb's Veterinary Drug Handbook, carprofen monograph, adverse effects and monitoring
This page summarizes and explains publicly available veterinary drug information. It is not a substitute for the official prescribing information your vet or pharmacist provides with your specific prescription.