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 dogs. Call your vet or poison control today, even if your dog seems fine.
If your dog may have eaten something harmful, 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 dogs
Toxic
Severity
4 / 5 — Serious — call your vet or poison control today.
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
Onions are an Allium. The N-propyl disulfide in them damages red blood cells and causes hemolytic (Heinz body) anemia. Cooked, raw, dried and powdered all count — onion powder in gravy, soup, baby food or takeaway is a common hidden source.
Signs to watch for if your dog 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 vary with the amount and with the individual pet, and some appear only after a day or more. Their absence does not mean your dog is in the 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 dog 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. With some substances it causes more damage than the poison. This page tells you when to get help — it never tells you how to treat at home.
Safer alternatives for dogs
Plain baby carrots or carrot sticks
Plain cooked chicken breast — no skin, no bones, no seasoning
A few blueberries or a slice of apple with the core removed
Verdicts are transcribed from the cited veterinary sources, never inferred. Where a source establishes a finding for one species only, the other species is left null and the page says to ask your vet — a dog finding is never copied onto a cat.
This page is a reference, not veterinary advice or a diagnosis. CanMyPetEat is a reference, not veterinary advice or a diagnosis. It tells you when to get help — never how to treat at home. Never induce vomiting or give any medicine unless a vet tells you to. Individual pets vary and toxicity guidance changes; your vet and the ASPCA Animal Poison Control Center are the authority.
No — onions are toxic to dogs. Call your vet or poison control today, even if your dog seems fine. Onions are an Allium. The N-propyl disulfide in them damages red blood cells and causes hemolytic (Heinz body) anemia. Cooked, raw, dried and powdered all count — onion powder in gravy, soup, baby food or takeaway is a common hidden source.
What happens if a dog eats onions?
Watch for: 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 take hours or, for some poisons, a day or more to appear, so call your vet rather than waiting to see.
How many onions are dangerous for a dog?
More than a taste can cause real illness, and the risk rises with the amount and with a smaller pet. The safe amount is none — if your dog has had more, call your vet.