My cat ate onion – what should I do?
Call a vet todayCall your vet today for advice – don't wait until signs appear. Onion is poisonous to cats and can damage red blood cells.
What to do right now
- Call your vet or the nearest emergency vet.
- Note what, how much and when.
- Bring the packaging.
- Remove what is left.
- Keep your cat calm.
Don't
- Do not make your cat vomit unless a vet tells you to.
- Do not give your cat any human medicine.
Why it can be dangerous
Onion belongs to the Allium family, which is poisonous to cats.[2] In cats, eating 5 g/kg of onions is enough to cause clinically important changes in the blood.[3]
Signs to watch for
What the experts say
“the ingestion of 5 g/kg of onions by cats and 15–30 g/kg by dogs is enough to cause clinically important hematologic changes”
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Common questions
How much onion is dangerous for a cat?
In cats, eating 5 g/kg of onions is enough to cause clinically important changes in the blood.[3]
What signs should I watch for?
The listed signs are vomiting, diarrhea and anemia.
What should I do now?
Call your vet or the nearest emergency vet, note what, how much and when, and bring the packaging.
Sources
- US FDA – Center for Veterinary Medicine
- Pet Poison Helpline
- Cortinovis & Caloni 2016, Household Food Items Toxic to Dogs and Cats, Front Vet Sci
How this page was made: written with the help of AI from the sources below, then checked claim by claim against those sources. Urgency levels follow OkPaw’s fixed safety rules. It is guidance, not a diagnosis. How we write our pages
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