Get

In Your Inbox

Catster is reader-supported. When you buy via links on our site, we may earn an affiliate commission at no cost to you. Learn more.

Can Cats Eat Onions? Vet-Reviewed Risks & Dangers

Can Cats Eat Onions

Any cat owner knows that our felines don’t always make the best choices about what they put in their mouth. Even the pickiest eaters will delight in snacking on your houseplants. So, if your kitty decides to eat either an onion or a dish that has onions in it, you may ask: Can cats eat onions? The answer is simple: no, never.

Your cats should stay away from onions at all costs, and that includes raw, cooked, and powdered forms of this potent veggie. But what makes onion so dangerous for your kitty? Let’s explain.

divider 2 catsHow Dangerous Are Onions for Cats?

Onions have the component oxidant n-propyl disulfide in them. Even eating the smallest amount of onion requires veterinary attention. Onions can make your cat extremely sick and even prove fatal if they aren’t treated immediately.

Your cat can suffer from onion toxicity because these plants cause red blood cells in your cat’s body to weaken and be destroyed. Red blood cells are responsible for carrying oxygen from the lungs all over your cat’s body, as well as carrying carbon dioxide away from your cat’s body back to their lungs. Weakened and non-functional red blood cells essentially deprive a cat of oxygen. It goes without saying that such a state is very detrimental for a cat. A state of low red blood cells is known as anemia. Though there are many types of anemia, they all are extremely detrimental to almost all domestic pets, including dogs and cats.

Unlike humans, their bodies just aren’t made with the correct elements to digest onions. Cats are even more sensitive than dogs to the effects of onions.

onion bulb-pixabay
Image Credit: mattycoulton, Pixabay

Can Cats Eat Garlic, Chives, or Leeks?

Garlic, onion, leeks, shallots, and chives are in the Allium genus. All allium plants contain the same harmful components that onions do, with garlic being at the top of the scale. Potency does play a factor, but any exposure to allium plants is unsafe.

Because the signs might not appear for up to 5 days after consumption, it’s crucial to know what to look for.

Signs of Onion Toxicity

If your cat has eaten part of an onion or eaten any food containing onion, you need to get them to your vet immediately. However, if you’re unaware it happened but notice the following signs, know that medical attention is imminent.

Signs of onion toxicity are:
  • Lethargy
  • Weakness
  • Salivation
  • Pale gums
  • Vomiting
  • Diarrhea
  • Lack of coordination
  • Decreased appetite
  • Blood in the urine
  • Yellow mucous membranes

If you notice any of these signs, don’t wait. Something may be seriously wrong with your kitty and they need you to be proactive.

If you need to speak with a vet but can't get to one, head over to PangoVet. It's an online service where you can talk to a vet online and get the advice you need for your pet — all at an affordable price!

PangoVet_Mention-in-Content for PangoVet2 save money

Diagnosis and Treatment

When you take your cat to see their vet after eating onions, they will do an immediate evaluation of the situation with all the necessary tests. Depending on the severity or amount, your vet may prescribe fluid therapy, administer charcoal treatments, or do blood testing.

The prognosis for minor episodes of onion ingestion is good if the amount consumed was minimal, you act fast, and your cat receives prompt medical attention. Even trace amounts of onion can damage your cat’s red blood cells, so observation and treatment are time-sensitive and crucial.
divider 2 cats

Foods to Watch Out For

Some foods might contain onion without you realizing it. Also, rarely, some products that are designed for cats could contain this lethal ingredient. Be very careful and always review any new food or snacks. If you find your cat reacting badly to a recently bought snack, it may be time to check the label.

You might not realize it, but many things contain onion powder, which is still highly toxic for cats. You might think nothing of sliding your cat a nice sliver of delicious chicken from takeout, but beware of the seasonings. Onion is remarkably popular for food flavoring.

Some foods that may contain onion include:
  • Baby food
  • Seasoned meat
  • Certain types of broth
  • Gravy
  • Several sauces
  • Canned soup

Before you offer any table scraps or human food to your cat, do a quick sweep of what additives are in the recipe.

divider 2 cats

Final Thoughts

Keep your cat away from onions in all forms at any cost. It doesn’t matter if a portion of food only has a tiny amount of onion—it’s bad news for your feline. Plus, you’ll rack up a ton of vet bills that you can avoid simply by keeping them away in the first place.

Of course, we all know that cats are sneaky and do what they wish. If your innocent, defenseless feline swiped a piece of onion from your plate, contact your vet for further advice.

See Also: 


Featured Image Credit: Catster.com

Want content like this delivered to you?

Sign Up For Our Newsletter

News, insights, expert advice, and everything cat

* By submitting, you agree to our Terms & Conditions and Privacy & Cookies Policy.

How useful was this post?

Click on a star to rate (you can leave written feedback after clicking submit)

Help us improve Catster for pet parents!

Your feedback really matters.

What did you like about this post? Also how can we improve it?

Join the conversation

Leave a Reply

You’re very welcome to leave a comment or question. Please know that all comments must meet our community guidelines, and your email address will NOT be published. Let’s have a positive and constructive conversation.

Talk With A Vet Online

Peace of mind,
anywhere, anytime

Affordable vet advice

Cats in Nursing Homes: Vet-Reviewed Benefits, Risks & FAQ

It’s a common practice to have therapy animals visit nursing home residents. They usually have scheduled visits where residents can interact with them...

10 Best Diabetic Cat Foods in Australia in 2026: Reviews & Top Picks

The world of pet food is a challenging one and it’s easy to get lost in the mess. As owners, we’re just trying...

National Cat Day in Japan 2026: How & When Is It Celebrated?

National Cat Day in Japan is celebrated on February 22 every year. This date was chosen because the date in Japanese resembles “nyan,...

10 Common Cat Grooming Mistakes & How Not to Make Them

Cats are fastidious groomers who pride themselves on their cleanliness. However, that doesn’t mean you don’t have to do your part to keep...

More related

Can You Use Dog Nail Clippers on Cats? Care & Safety Tips

All cat parents know that felines require regular maintenance to keep them looking clean and neat and most importantly, ensure that they’re healthy....

The Secret to Getting Your Cat to Love Your New Kitten

Bringing home a new kitten is supposed to be exciting until your resident cat gives you the look. The hissing, hiding, or cold...

How to Travel With a Cat in a Car: 11 Tips & Tricks

As much as we love our cats, the idea of traveling with them in a car on a long-distance trip can be daunting...

Why Are My Cats Fighting All of a Sudden? 5 Vet-Approved Reasons & Tips

There is something so disheartening about two best pals turning into enemies. If your cats have always gotten along but seem to be...

Keep reading

That Crusty Red Spot on Your Cat’s Lip Isn’t What You Think

You’re petting your cat when your thumb brushes something rough on their lip. You pull back to look, and there it is: a raised, reddish patch that definitely wasn’t there last week. Your stomach drops a little. What is that?...

veterinarian checking the mouth of cat

Are Bromeliads Toxic to Cats? Vet-Reviewed Houseplants Examined

Bromeliads are plants that are easy to grow and add a tropical vibe to the inside of your home. Even if you’re a beginner at growing plants or don’t have a green thumb whatsoever, these plants do not take much...

Catster_Are Bromeliads Toxic to Cats

Why Is My Cat Standing on His Hind Legs? Possible Reasons & When To Be Concerned (Vet-Verified)

It’s not uncommon for cat owners to catch their cats doing crazy things, like chasing their tails or staring wide-eyed into the distance. If you caught your cat standing on their hind legs, you may wonder what alternative universe you...

calico-cat-having-treats

How to Tell if a Cat Is Cold – 5 Vet Approved Signs to Look For

As a proud cat owner, you certainly only want what’s best for your precious little pet. When the temperature outside drops, you probably pull out your blankets and sweaters to keep warm. But what about your cat? If you’re wondering...

cat curling up in a box

Why Does My Cat Have a Stuffy Nose? 9 Vet Reviewed Reasons

If your cat has suddenly started sneezing and has trouble breathing through their nose, you might be a bit worried. Cats end up with sniffles and stuffy noses, technically known as rhinitis, for various reasons, from allergies to colds. While...

cat nose -pixabay

11 Best Cat Litters in 2026 – Reviews & Top Picks

Cats are truly some of the most unique domesticated animals and are exceptionally clean. They’re always grooming themselves, avoiding dirty situations as much as possible, and taking extraordinary measures to keep their waste out of sight. Despite their best efforts,...

Litter tray and scoop for cat on floor

Balinese Cat Health Problems: 16 Vet-Reviewed Health Issues

The Balinese is a beautiful cat breed closely related to the Siamese, but these cats can be prone to certain health problems, some of which are quite serious, and many can be inherited and passed over to new generations of...

How to Keep a Collar on a Cat: 5 Vet-Verified Easy Tips & Tricks

Whether a breakaway or traditional product, keeping a collar on a cat can be quite a task for every pet owner. While most people associate collars with dogs, it’s also a good idea for your cat to wear one if...

cat with red calming collar