In the UK, carprofen is a POM-V medicine — prescription-only, veterinary — dosed at 4.4 mg/kg once daily or 2.2 mg/kg twice daily, and sold as Rimadyl, Carprodyl, Canidryl, Rimifin and Dolagis among others. Two things British owners have that most articles never mention: a legal right to a written prescription, which can cut the cost of long-term treatment substantially, and a direct route to report a suspected adverse reaction to the Veterinary Medicines Directorate without going through anyone. This guide covers both, alongside what the veterinary literature actually shows about how well carprofen works and where the real risks sit.
POM-V: what that classification means for you
POM-V medicines can only be prescribed by a veterinary surgeon following a clinical assessment of the animal, and supplied by a vet or pharmacist against that prescription. There is no legitimate route to buy carprofen without a prescription in the UK, and a site offering one is not operating within the Veterinary Medicines Regulations.
Your vet must also see the dog periodically to continue prescribing. Most practices work on a re-examination every three to six months for a dog on long-term NSAIDs, often bundled with the recheck bloodwork described below. That visit is not a revenue exercise — it is the mechanism by which liver and kidney problems get caught before they become clinical.
The written prescription most owners never ask for
Under RCVS guidance, you are entitled to ask your vet for a written prescription rather than buying the medicine from the practice, and to have that dispensed by a registered online veterinary pharmacy. The practice may charge a prescription fee. For a large dog on carprofen indefinitely, the arithmetic often still favours the written prescription — and the CMA's review of the veterinary sector has pushed practices toward making that option visible rather than buried.
Ask two questions at the next appointment: what is your prescription fee, and how long is the prescription valid for. Then compare against the practice's own dispensed price for a three-month supply. It is a five-minute conversation that some owners find saves them a meaningful sum a year.
Carprofen dosage for dogs
| Dog weight | Total daily dose (4.4 mg/kg) | Split (2.2 mg/kg twice daily) |
|---|---|---|
| 5 kg | 22 mg | 11 mg twice daily |
| 10 kg | 44 mg | 22 mg twice daily |
| 20 kg | 88 mg | 44 mg twice daily |
| 30 kg | 132 mg | 66 mg twice daily |
| 40 kg | 176 mg | 88 mg twice daily |
This is the licensed dose, printed so you can check the label you were handed — not so you can dose at home. UK data sheets are published on the VMD's Product Information Database, which is the authoritative source for whichever brand your practice dispensed. Vets commonly prescribe below the licensed figure in older dogs or dogs with borderline renal values, and that is a clinical decision made with bloodwork in front of them.
How well it works: the 805-dog field study
The largest published field study treated 805 lame osteoarthritic dogs across 51 clinics with 4 mg/kg for 84 consecutive days, dosed by their own owners at home (Mansa et al., Veterinary Record 2007, PMID 17400900). By day 84, 194 dogs — 26.7% — were no longer lame and 357 — 49.2% — had improved. Twenty-four dogs, 3.0%, came off the study because of side effects.
Two findings from that paper deserve more circulation than they get. How long the dog had been lame before treatment started significantly affected the result (P<0.01) — earlier treatment did better. And too much exercise during the 84 days caused relapses, because a dog with the pain switched off will cheerfully overload the joint you are trying to protect.
A systematic review of canine NSAID studies placed carprofen in the highest evidence tier alongside firocoxib and meloxicam (Monteiro-Steagall et al., JVIM 2013, PMID 23782347) — while noting that most safety studies were conducted in healthy, non-geriatric research dogs rather than the arthritic thirteen-year-old actually being prescribed it.
Side effects: the numbers behind the leaflet
Video capsule endoscopy in dogs receiving an NSAID for at least 30 days — a median of six months, mostly carprofen — found gastrointestinal erosions in 10 of 12 dogs, 83.3%, significantly more than controls (Mabry et al., JVIM 2021, PMID 33534961). Most were subclinical. "He's been on it for years and he's fine" describes symptoms, not mucosa.
A 2025 JAVMA case series of 33 dogs with confirmed ulceration found eleven had ulcerated on a single COX-2-sparing NSAID at an appropriate dose — and every one of the five dogs receiving two NSAIDs concurrently suffered a full-thickness perforation (Hillier et al., PMID 39426398). Idiosyncratic liver injury is the other well-documented reaction, described in 21 dogs presenting with inappetence, vomiting and jaundice, most of whom recovered once the drug was withdrawn (MacPhail et al., JAVMA 1998, PMID 9638189).
Reporting a suspected reaction: you can do this yourself
The UK operates a veterinary pharmacovigilance scheme run by the Veterinary Medicines Directorate, and — this is the part most owners do not know — animal owners can submit a suspected adverse event report directly, not only vets. Reports feed into the ongoing safety review of every authorised product.
If your dog reacts badly to carprofen, tell your vet first and get the dog seen. Then, separately, report it. The system only works if the events reach it.
The rules that prevent the worst outcomes
- Never two NSAIDs together. Not carprofen plus leftover meloxicam, not carprofen plus human ibuprofen or aspirin. Five out of five dogs on concurrent NSAIDs perforated in the series above.
- Never with corticosteroids — prednisolone, dexamethasone — unless your vet has explicitly directed it.
- Observe the washout period when switching between NSAIDs. Your vet sets the interval.
- Give with food, and not to a dog that is off its water. Dehydration is the main multiplier of renal risk.
- No human painkillers. Ibuprofen, naproxen and paracetamol are among the most common causes of emergency poisoning presentations in dogs.
Monitoring schedule
| Stage | Typical UK practice |
|---|---|
| Before the first dose | Baseline haematology, biochemistry and urinalysis |
| 2–4 weeks in | Recheck liver enzymes and renal values |
| Every 3–6 months | Re-examination and repeat bloods while treatment continues |
| Any new sign | Stop the drug, phone the practice the same day |
Check your pet insurance policy wording too. Long-term medication for a chronic condition is where exclusions and per-condition limits bite, and osteoarthritis is a condition many policies treat as ongoing from the date of first signs — not the date of diagnosis.
Ring the practice the same day if you see
- Repeated vomiting, or vomit resembling coffee grounds
- Black tarry faeces, or fresh blood
- Loss of appetite — the commonest first sign of liver injury
- Yellowing of gums, eyes or skin
- Marked lethargy, or sudden increased thirst and urination
- Restlessness, disorientation or uncharacteristic aggression
Do joint supplements help alongside carprofen?
They are not contraindicated, and vets frequently run both within a multimodal plan. But here is the evidence going against our own commercial interest: a 2022 knowledge summary in Veterinary Evidence reviewed two prospective block-randomised trials of marine omega-3s added to NSAID therapy and found no statistically significant difference versus the NSAID alone at week 2 or week 4, on limb force or orthopaedic assessment score (Wong & Govendir, PMID 42007295).
So no, a supplement does not let your vet cut the carprofen dose — nobody has demonstrated that in a controlled trial. Where daily joint support does earn its place is earlier: the stiff-after-a-nap, hesitant-on-the-stairs stage before a prescription is on the table. Our Hip & Joint Chews carry 18 named actives — glucosamine HCl and chondroitin sulfate as the base, plus MSM, green-lipped mussel, UC-II undenatured type II collagen, hyaluronic acid, eggshell membrane, boswellia and turmeric at 95% curcumin — rather than the two or three most chews stop at. Our best joint supplements for dogs guide grades the category on named dosages rather than claims.
If carprofen is no longer holding your dog's pain, the next conversation is usually about other prescription options: Librela for dogs and Adequan for dogs cover the two most common, and dog arthritis medicine maps the wider landscape. Alongside all of it, the non-drug levers in how to help a dog with arthritis at home — weight, flooring, ramps, controlled lead exercise — remain the highest-yield thing most owners are not doing. If you are still at the stage of working out what you are seeing, start with arthritis in dogs symptoms. The full US guide is carprofen for dogs.
What we will not tell you
- That any supplement replaces carprofen, reduces a prescribed dose, or treats osteoarthritis.
- That carprofen should be avoided. It carries the strongest evidence base of any canine NSAID.
- That you can dose, adjust or stop and restart it around flare-ups without speaking to your vet.
- A universal side-effect rate. The 3.0% withdrawal figure is one study, one protocol, 84 days.
Frequently asked questions
Can I buy carprofen for my dog without a prescription in the UK?
No. Carprofen is POM-V — prescription-only, veterinary — and can only be supplied against a prescription written by a vet who has clinically assessed your dog. You can, however, ask for a written prescription and have it dispensed by a registered online veterinary pharmacy.
How much carprofen for a 20 kg dog?
The licensed dose works out at 88 mg daily, or 44 mg twice daily, but the correct dose for your dog is the one on the label your vet dispensed. Never dose from a chart, and never use another dog's tablets.
How long can a dog stay on carprofen?
Many dogs take it for years under monitoring — baseline bloods, a recheck at two to four weeks, then every three to six months. Bear in mind that subclinical gastrointestinal erosions were found in 83.3% of dogs on chronic NSAID therapy in one capsule-endoscopy study, so no visible symptoms is not the same as no injury.
How do I report a bad reaction to carprofen?
Get your dog seen by your vet first. Then submit a suspected adverse event report to the Veterinary Medicines Directorate — owners can report directly, not only vets, and those reports feed the ongoing safety review of the product.
Is Rimadyl the same as carprofen?
Yes. Rimadyl, Carprodyl, Canidryl, Rimifin and Dolagis are UK brand names for the same active substance. Do not assume equivalent tablet strengths between brands — read the label each time you collect a repeat.
References
- Mansa S, et al. Long-term treatment with carprofen of 805 dogs with osteoarthritis. Veterinary Record. 2007;160(13):427-30. PMID 17400900
- Mabry K, Hill T, Tolbert MK. Prevalence of gastrointestinal lesions in dogs chronically treated with NSAIDs. JVIM. 2021;35(2):853-859. PMID 33534961
- Hillier TN, et al. Dogs receiving COX-2-sparing NSAIDs and/or nonphysiologic steroids are at risk of severe gastrointestinal ulceration. JAVMA. 2025;263(3). PMID 39426398
- MacPhail CM, et al. Hepatocellular toxicosis associated with administration of carprofen in 21 dogs. JAVMA. 1998;212(12):1895-901. PMID 9638189
- Monteiro-Steagall BP, Steagall PV, Lascelles BD. Systematic review of NSAID-induced adverse effects in dogs. JVIM. 2013;27(5):1011-9. PMID 23782347
- Wong LYS, Govendir M. Marine-derived omega-3 fatty acids as an adjunct to NSAID therapy vs NSAID alone, for dogs with osteoarthritis. Veterinary Evidence. 2022;7(1). PMID 42007295
Educational content, not veterinary advice. Carprofen is a POM-V medicine and must be prescribed, dosed and monitored by a veterinary surgeon who has examined your dog. Pure Majesty Pets products are complementary feeds, not veterinary medicines: they are not intended to diagnose, treat, cure or prevent any disease. Rimadyl, Carprodyl, Canidryl, Rimifin, Librela and Adequan are registered trademarks of their respective owners; Pure Majesty Pets is not affiliated with them.
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