Rimadyl vs Onsior
A detailed comparison of Rimadyl and Onsior for dogs. Which is the better choice? We compare ingredients, dosing, price, and side effects.
Rimadyl
Carprofen chewable tablets — an established NSAID for pain and inflammation in dogs, particularly post-surgical and arthritis pain.
Onsior
Robenacoxib tablets — a newer-generation COX-2 selective NSAID for dogs with a focus on minimising GI side effects.
Save on Rimadyl or Onsior at a UK pharmacy
UK registered pharmacies dispense the same prescription medications as your vet, often for less. Ask your vet for a written prescription, then fill it online.
Affiliate links to The Pharm Pet Co., a UK registered veterinary pharmacy. We may earn a small commission, at no extra cost to you. Always follow your vet's guidance on medication choice and dosing.
Side-by-Side Comparison
| Feature | Rimadyl | Onsior |
|---|---|---|
| Active Ingredient | Carprofen | Robenacoxib |
| Form | Chewable tablet | Tablet |
| Frequency | Once or twice daily | Once daily |
| Species | Dogs | Dogs |
| Price Range | £15–£35/box of 20 | £15–£40/box |
Key Differences
GI safety
Onsior is more COX-2 selective, meaning lower risk of stomach/intestinal side effects.
Palatability
Rimadyl chewable tablets are liver-flavoured treats; Onsior tablets are plain.
Half-life
Onsior clears the body faster — advantageous for dogs with liver/kidney concerns.
Long-term data
Rimadyl (carprofen) has been used for decades; Onsior is newer with less long-term data.
Cost
Rimadyl is cheaper, especially in generic carprofen form.
Pros & Cons
Rimadyl
Pros
- Chewable liver-flavoured tablet — easy to give
- Rapid pain relief
- Long track record in veterinary medicine
- Generic versions available for savings
Cons
- Less COX-2 selective — higher GI risk than Onsior
- Liver monitoring recommended for long-term use
- Can cause appetite changes
- Prescription only
Onsior
Pros
- Most COX-2 selective veterinary NSAID available
- Lowest theoretical GI risk
- Short half-life — rapid clearance if problems occur
- Once daily dosing
Cons
- More expensive
- Less palatable — not a chewable treat
- Smaller body of long-term safety data
- No generic version available
Compare Prices & Save
Both Rimadyl and Onsior may be cheaper from a licensed online retailer than from your vet. Ask for a written prescription and compare prices.
Important: This comparison is for informational purposes only and is not veterinary advice. Always consult your vet before starting, stopping, or switching your pet's medication. Prices shown are typical UK ranges and may vary by product size, weight band, and retailer.
Alternative options to consider
Retailers we earn a commission from. It costs you nothing and never changes what we show.
The Pharm Pet Co. — Pet Pharmacy
UK online pet pharmacy. Flea, worm, prescription medications, supplements and pet food. Save vs vet prices.
Pet Care at Pharmacy2U
The UK's largest online pharmacy. Pet wormers, flea treatments, dental and joint care. Free delivery on orders over £30.
YuMOVE Joint Care for Dogs
The UK's number-one selling joint supplement for dogs. Triple action with green-lipped mussel, glucosamine and hyaluronic acid. Works in six weeks or money back.
We may earn a small commission if you purchase through these links, at no extra cost to you.