Cats · Guide
Can Cats Eat Onions?
No, onions are toxic to cats in any form. Even small amounts can harm red blood cells. Learn which forms count, the signs to watch for, and what to do.
No, cats should not eat onions. Raw, cooked, or dried, onions can damage a cat’s red blood cells and lead to anemia, which means the blood can’t carry enough oxygen. Cats are more sensitive than dogs, so even a small amount is a reason to call your vet.
Why are onions bad for cats?
Onions belong to the Allium family, along with garlic, chives, and leeks. The Merck Veterinary Manual says these plants contain sulfur compounds that damage red blood cells. The damaged cells form clumps called Heinz bodies, and the body removes them too fast. This is called hemolytic anemia.
Merck calls cats the most sensitive species, with dogs next. The ASPCA also says cats are more at risk than dogs. Merck notes that very small amounts can be a problem for a cat. The ASPCA names the harmful compound as N-propyl disulfide.
Are cooked onions safe for cats?
No. Cooking does not remove the danger. Merck says raw, cooked, dried, and powdered onion can all be toxic. This includes onion in soup, gravy, stuffing, and sauces. Onion powder is also found in some seasonings and human foods.
Other kinds of onion
Are green onions safe for cats?
No. Green onions (also called scallions) are Alliums too. Pet Poison Helpline lists green onions, chives, leeks, and shallots as poisonous to cats, dogs, and livestock. The same goes for the white and green parts. Treat them like any other onion.
What about chives, leeks, and garlic?
Also no. Pet Poison Helpline and the ASPCA list chives, leeks, and garlic as risky for cats. Merck says garlic is about 3 to 5 times more toxic than onion.
What about onion powder and cooked onion?
No. As above, Merck says dehydrated and cooked onion are toxic too. Check ingredient labels before sharing any human food.
What are the signs of onion poisoning in cats?
The ASPCA lists these signs:
- Vomiting
- Weakness
- Fast heart rate and panting
- Blood in the urine
Pet Poison Helpline also lists nausea and diarrhea. Merck says signs of anemia usually appear several days after eating onion, about 3 to 5 days. They include tiredness, not wanting to eat, fast breathing, yellow skin or gums, dark urine, and collapse. Don’t wait for these signs before you call.
What should I do if my cat ate onion?
- Take any onion or food away from your cat.
- Call your vet or a poison hotline right away. Tell them what your cat ate, how much, and when.
- Follow their advice. Merck says early treatment to remove the onion from the stomach helps. Cats with anemia may need oxygen, fluids, or blood transfusions.
Don’t try to make your cat vomit yourself unless a vet tells you to.
How much onion is too much?
No safe amount is known. Merck says even very small amounts can cause harm in cats, so the best plan is none at all. Keep your cat out of the kitchen when you cook, and clean up scraps right away. Don’t share table scraps that might have onion or onion powder in them.
Safer treats for your cat
Skip the table scraps and ask your vet which treats suit your cat. See our guide on eggs for cats and the full list of foods that are toxic to cats. Treats should stay under about 10% of your cat’s daily calories.
Common questions
How much onion is toxic to a cat?
The Merck Veterinary Manual says cats are the most sensitive pet, and very small amounts can cause harm. No safe amount is known, so treat any onion as a reason to call your vet.
How long after eating onion will a cat get sick?
Merck says signs of anemia often show up several days after the onion is eaten, usually 3 to 5 days. An upset stomach may come sooner. Call your vet right away instead of waiting.
Is onion powder safe for cats?
No. Merck says dried and powdered onion are toxic too. Onion powder is common in sauces, soups, and seasonings, so check labels.
Can my cat eat food that has onion in it, like soup or sauce?
No. Merck says cooked and dried onion are toxic too, so onion cooked into food still counts. Check the ingredients before you share human food.