Medication safety · 2 min read

Is Naproxen toxic to cats?

No — dangerous

No. Naproxen is an NSAID with an especially long half-life in cats — it stays toxic in the system far longer than other NSAIDs.

If your cat has just eaten naproxen

  1. Move your cat away from any remaining naproxen. Do not try to make them vomit at home — this is dangerous in cats and rarely works.
  2. Note how much was eaten and when, and keep the packaging or a photo of the plant/substance if you can.
  3. Call your vet immediately, even out of hours. Tell them your cat's weight, what they ate, and when.
  4. If you can't reach your vet, call Animal PoisonLine (01202 509000) — paid triage, 24/7 for guidance. They can advise on urgency and route you to emergency care.

What's the full picture?

Naproxen (UK brand Naprosyn and in some Nurofen Joint & Back products) is an NSAID that causes severe toxicity in cats at tiny doses.

Symptoms include vomiting (often bloody), abdominal pain, and — within 24-72 hours — acute kidney injury. Signs can be subtle at first.

Never give any NSAID to a cat. If you suspect exposure, go to the vet immediately — treatment is most effective in the first few hours.

Symptoms to watch for

0–6 hours
Vomiting, drooling, loss of appetite.
6–48 hours
GI bleeding, reduced urine output.
2–5 days
Acute kidney failure, anaemia from GI blood loss.

If you're worried right now

Call your vet or out-of-hours emergency vet first. For poison advice, the Animal PoisonLine (UK) is on 01202 509000 — 24/7, charges apply. Your vet can also call the Veterinary Poisons Information Service (VPIS) directly.

Aspirin no Diclofenac (Voltarol) no Ibuprofen no Nurofen no

About this guidance

Every entry on this site is compiled from published UK veterinary toxicology sources — International Cat Care, Veterinary Poisons Information Service (VPIS) references, RCVS-registered practice materials, and peer-reviewed feline medicine literature. Where the evidence is mixed, we err on the cautious side because cats are unusually sensitive to many common substances that are harmless to humans and even to dogs.

This is general information written for UK cat owners. It is not personalised veterinary advice for your specific cat, their age, weight, medical history, or the exact exposure you're dealing with. If your cat has eaten something or is unwell, call your vet first. The Animal PoisonLine on 01202 509000 is available 24/7 for a small fee and can tell you whether an emergency visit is needed.

Entries are reviewed and updated as new research emerges. Spotted an error? Let us know — corrections are investigated and applied within 24 hours. For more context on how we work, see about and our full disclaimer.

Last reviewed: · By the What Can My Cat Eat? editorial team

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