Can Cats Eat Onion?

NoEmergency risk
Verdict for cats: Toxic · Evidence: H · Last verified: 2026-11-01 (seed data — veterinary review pending)

No. Onion is toxic to cats. It contains N-propyl disulfide (Allium). There is no amount we can call safe, so it should stay off the menu. If your cat has already eaten some, contact your veterinarian or a pet poison hotline right away.

Your cat already ate some?
Don't wait for symptoms. Call your veterinarian now, or a pet poison hotline:
ASPCA Animal Poison Control (US): (888) 426-4435 (a fee may apply) · Pet Poison Helpline (US/CA): (855) 764-7661 (a fee applies)

Why it is toxic

N-propyl disulfide (Allium)

Which parts are the problem?

all forms

Dose & exposure rules

Even small amounts are dangerous for cats

If it must be on the menu: safe preparation

None — cats are more sensitive than dogs

Symptoms to watch for

lethargypale gumsred or brown urineweakness

Anemia delayed 1-5 days

What to do now

Vet visit even if asymptomatic

✔ Reviewed against ASPCA · Merck Vet Manual. Veterinary review pending — this page will carry a named, licensed veterinarian's sign-off after review (see team and editorial policy). General information only, not veterinary advice.

FAQ

How much onion can a cat eat?

Even small amounts are dangerous for cats

What are the signs of onion problems in cats?

Watch for: lethargy; pale gums; red or brown urine; weakness. Anemia delayed 1-5 days

What should I do if my cat ate onion?

Vet visit even if asymptomatic

Related:

Can dogs eat onion?

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