Can cats eat onions?

Updated 2026-08-07 · Source: ASPCA Animal Poison Control — People Foods to Avoid Feeding Your Pets; ASPCA Animal Poison Control — Toxic and Non-Toxic Plants database · Free · No sign-up

No — onions are toxic to cats, even in small amounts. Call your vet or the ASPCA Animal Poison Control Center at (888) 426-4435 now.

If your cat may have eaten something harmful — or any part of a lily — call your vet or the ASPCA Animal Poison Control Center at (888) 426-4435 right now — don't wait for symptoms. A consultation fee may apply to the ASPCA hotline.

Verdict for cats	Toxic
Severity	5 / 5 — Emergency — can be fatal, and small amounts can matter. Call now.
Safe amount	None
Category	Vegetable
Source	ASPCA Animal Poison Control — People Foods to Avoid Feeding Your Pets; ASPCA Animal Poison Control — Toxic and Non-Toxic Plants database · reviewed 2026-08-07 · confidence: high

Why

Cats are more susceptible to Allium poisoning than dogs, so a smaller amount matters more. Signs of anemia can take a few days to appear, which is why vets want to hear about the exposure straight away rather than after symptoms.

Signs to watch for if your cat has eaten onions

Vomiting, drooling or diarrhea
Weakness, tiredness or collapse
Pale or yellow gums
Red or brown urine
Fast breathing and a fast heart rate — signs can take 1–5 days to appear

Signs can lag by a day or more, so no symptoms does not mean your cat is clear — call rather than watch.

What to do now

Call your vet or the ASPCA Animal Poison Control Center at (888) 426-4435 straight away. Tell them what your cat ate, roughly how much, and when, and take the packaging with you. Don't wait for symptoms — with several poisons the harm is done before a pet looks ill.

Never induce vomiting and never give any medicine unless a vet tells you to — it can do more damage than the poison. What we will and won't tell you.

Safer alternatives for cats

A small piece of plain cooked chicken or turkey
Plain cooked fish, boneless and unseasoned
A vet-approved commercial cat treat, kept to under a tenth of daily calories
Cat grass grown indoors instead of houseplants
Fresh water — a fountain tempts many cats to drink more

What about dogs?

Can dogs eat onions? — Toxic for dogs.

This page is a reference, not veterinary advice or a diagnosis. Verdicts are transcribed from the cited source, never inferred, and a finding in one species is never copied onto the other. How we source and decide a verdict.