Can cats eat onion?
No. Onion is toxic to cats in every form — raw, cooked, dried or powdered. It can damage red blood cells and cause anaemia, and cats are the most sensitive species. Call your vet if your cat eats any.
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Why
Onion belongs to the allium family (the onion family). Alliums damage red blood cells and can lead to anaemia, and they also irritate the stomach and gut. Cats are the most sensitive species. All forms are poisonous to cats — raw, cooked, dried, powdered and liquid.
Signs to watch for
- Vomiting
- Diarrhoea
- Reduced appetite
- Weakness
- Pale gums
- Red-coloured urine
- Faster or harder breathing
What to do
Contact your vet or a pet poison helpline right away, even if your cat seems well — signs of anaemia can take several days to show. Note what your cat ate (raw, cooked, powder or a dish containing it), how much and when. Don't try to make your cat sick at home.
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Is cooked or powdered onion safe for cats?
No. All forms are poisonous to cats, including raw, cooked, dried, powdered and liquid onion. Be careful with leftovers, stuffing and gravy that may contain it.
Why do signs sometimes appear days later?
Tummy upset often shows first, but signs of anaemia usually take longer and can appear within one to five days. That is why you should call your vet straight away rather than wait.
Related foods
All foods: What can cats eat?Sources
- Garlic and Onion (Allium spp) Toxicosis in Animals — Merck Veterinary Manual (C. Hayes, ASPCA APCC; full review Sept 2024)
- Onion, Garlic, Chive, and Leek Poisoning in Cats — VCA Animal Hospitals (R. Schmid, DVM, DABT, for Pet Poison Helpline)
- Onion and Garlic Poisoning in Cats — PDSA (May 2023)
- People Foods to Avoid Feeding Your Pets — ASPCA Animal Poison Control Center
- Cats and human foods — Cats Protection
- Common cat poisons and toxins — Blue Cross
- Vet charity warns of fatal foods for furry friends this Christmas — PDSA press office (16 Dec 2021)
General information from the sources below, not reviewed by a vet and not a substitute for veterinary advice. When in doubt, call your vet.
How kids practise this in PetPrep
In PetPrep a child looks after a realistic cat: meals at the right times, water, walks and care. Knowing what is safe to share is part of being ready for a real pet.