Cat Food

Can Cats Eat Onions? What to Know About Cats and Onions

Can cats eat onions? What about raw onions vs. cooked onions? What should you keep in mind about cats and onions?

Sassafras Lowrey  |  Mar 21st 2019

For us humans, onions are a flavorful ingredient used both cooked and raw in many dishes. Onions might be delicious to us humans, but what about onions and cats? Can cats eat onions?

Can Cats Eat Onions?

A calico cat getting pet — might be sick or at rest.

Wondering, “Can cats eat onions?” Let’s take a look. Photography © krblokhin | iStock / Getty Images Plus.

The answer to, “Can cats eat onions?” is pretty clear. Onions are extremely dangerous for cats, even in small amounts. If veterinary care is not immediately sought after a cat eats onions, ingesting onions could even be fatal to cats.

Emmy-award winning veterinarian Dr. Jeff Werber  explains that cats are very sensitive to onions and it doesn’t take very much onion to make them very sick. Onions are especially dangerous to cats because they could cause anemia, liver damage and even death. 

Can Cats Eat Onions In Any Amount?

As touched on above, even a small amount of onion can be dangerous to cats.  Dr. Amy Mathiak, of Firehouse Animal Health Center, says that she considers a cat consuming any amount of onion as an emergency that requires immediate veterinary intervention.

Can Cats Eat Onions That Are Raw? Can Cats Eat Onions That Are Cooked?

The next question you might have after, “Can cats eat onions?” might be about raw vs. cooked onions. “The most dangerous are raw onions, then dehydrated, then cooked,” Dr. Werber explains, “but, again, all onions, in all forms — raw and prepared — are dangerous to cats.”

Dr. Mathiak says that cats aren’t generally tempted to eat raw onions. Cats usually get exposed to onions from cooked and processed human foods. She also cautions that onions are a surprisingly frequent additive in processed foods. It’s not advised to share human foods with your kitty unless checking in with a vet first, but if you do choose to give your cat some people food, make sure there are no onions in it.

What Should You Do If Your Cat Eats Onions?

Now that we’ve laid out some answers to, “Can cats eat onions?” let’s look at what to do in the unfortunate event that your cat eats onions.

Since even a small amount of onion can make a cat extremely sick, don’t share any “people food” with your cat that could contain onion. Cats can be sneaky, so it’s a good idea to exercise extra caution when cooking with onions or preparing foods that have onions as an ingredient.

If you even think that your cat ate onions, or something that contains onions, Dr. Mathiak advises cat guardians to head to the vet immediately. Do not attempt to treat your cat at home. Dr. Werber says that it is not safe to attempt to induce vomiting. Dr. Mathiak echoes this concern by cautioning that the usual methods people use to try to get cats to vomit are generally ineffective. Get your cat to your vet or a veterinary hospital for care as soon as possible.

Treatment for a Cat Who Ate Onions

When a cat who has ingested onions gets to a veterinarian, there are a few courses of treatment. If the cat has ingested onions in the past few hours, the vet will likely try to induce vomiting (again, do not attempt this at home yourself). The vet will also get baseline lab work on blood and urine, which will help determine how severe the onion exposure was.

“Based on symptoms and diagnostics, we will either attempt life-saving blood transfusions and oxygen therapy and/or supportive care for milder GI issues,” explains Dr. Mathiak.

It’s important for your cat to get treatment as soon as possible, however the side effects of ingesting onions can take a while to present. “The onset of severe symptoms, depending on the amount ingested, can be delayed five to seven days,” Dr. Mathiak cautions. “The most important thing that you can do if your cat eats onion is to seek veterinary care for your cat.”

Thumbnail: Photography © velkol | iStock / Getty Images Plus.

About the author

Sassafras Lowrey is an award-winning author and Certified Trick Dog Instructor. Forthcoming books include: “Tricks IN THE CITY: For Daring Dogs and the Humans That Love Them,” “Healing/Heeling” and “Bedtime Stories for Rescue Dogs: William To The Rescue.” Sassafras lives and writes in Portland, Oregon with three cats and three dogs. Learn more at

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