| 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 |
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.
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 — it can do more damage than the poison. What we will and won't tell you.
Can cats eat onions? — Toxic for cats.
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.
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. Some signs lag by a day — call, don't wait.
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.