Can cats eat Walnuts?
No. Walnuts contain juglone and are prone to mould that produces tremorgenic mycotoxins — both are dangerous to cats. The high fat load also raises pancreatitis risk. Don't feed, and keep walnut trees' fallen nuts away from outdoor cats.
Responsible cat owners also keep parasite protection up to date — Best Vet Care ships prescription flea, tick and wormer treatments direct from licensed vets. (affiliate link)
Content compiled with reference to guidance from the Blue Cross, PDSA, Royal Veterinary College (RVC), Battersea, and Animal PoisonLine. This site does not provide veterinary advice — always consult a vet. Last reviewed: 27 September 2026.
Key facts
- Verdict: No — dangerous to cats. Walnuts should never be given deliberately.
- Category: Nuts
- Onset: Signs can start 0–12 hours — see the full timeline below.
- If it's already happened: Call your vet now, or the Animal PoisonLine on 01202 509000 (24/7, charges apply) — see the emergency steps below.
If your cat has just eaten walnuts
- Move your cat away from the walnuts.
- Don't induce vomiting at home — this is dangerous in cats.
- Call your vet or out-of-hours emergency vet immediately.
- If you can't reach a vet, call the Animal PoisonLine on 01202 509000 — 24/7, charges apply.
- Note how much walnuts was eaten, when, and your cat's weight.
What's the full picture?
Walnuts are more dangerous than most culinary nuts because of juglone (a toxin produced by the tree) and the ease with which walnuts develop mould during storage. Mouldy walnuts can cause tremors and seizures in cats.
Cats don't often seek out walnuts, but will chew on them if they find one on the floor or play with them as batting toys. Cracked or mouldy walnuts are the most dangerous.
Owners with walnut trees should clear fallen nuts regularly — these can mould quickly in British weather and be picked up by outdoor cats.
Symptoms to watch for
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Cat owner essentials
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Questions owners ask
How much walnut is dangerous to a cat?
A single intact, fresh walnut chewed briefly during play is unlikely to cause serious harm, but a mouldy or cracked walnut carries a real risk of tremorgenic mycotoxins even in a small amount — mould can develop invisibly inside the shell. There's no reliable way to judge mould exposure from the outside, so treat any confirmed ingestion of walnut, especially from fallen garden nuts, as worth a vet call if you notice tremors, restlessness, or vomiting.
How would I know if a walnut was mouldy after my cat has already eaten it?
You often can't tell in advance, which is why monitoring the cat's symptoms matters more than trying to inspect the nut. Watch for vomiting, restlessness, tremors, or diarrhoea within 12 hours — tremors specifically point toward mould-related mycotoxins rather than simple digestive upset, and warrant an urgent vet call rather than waiting to see if they settle.
Are there safer nut-like treats for cats that enjoy the shape or crunch?
There's no nutritional reason to give a cat any nut, walnut or otherwise — a crunchy commercial cat treat satisfies the texture preference without the mould, juglone, or fat-related risks. If your cat has taken an interest in batting around fallen nuts as toys rather than eating them, redirect that instinct with a proper cat toy instead.
A cat water fountain encourages drinking, which supports the kidneys — worthwhile for any cat that's had a dietary scare.
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Related
Sources referenced for this guidance
- Veterinary Poisons Information Service (VPIS) — UK clinical toxicology reference used by vets
- International Cat Care — feline-specific clinical guidance
- BSAVA — British Small Animal Veterinary Association reference materials
- Merck Veterinary Manual — professional veterinary reference
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