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

What Kind of Cat Breed Is Marie from The Aristocats? Disney Felines Explained

One of Disney’s claims to fame is having the most adorable, animated animals. One of the most popular to date is Marie, a...

How to Get Rid of Cat Pee Smell: Tips for Every Surface

One of the worst things about owning a cat is the possibility of cat pee on your carpet or wooden floors. Every cat...

Thai Cat Breed: Info, Pictures, Temperament & More

Perhaps you love the colorpoint pattern of the Siamese but would prefer a cat with more rounded edges. You need to meet the...

How Big Do British Shorthairs Get? Vet-Reviewed Growth & Weight Chart

The British Shorthair is a sturdy cat with a strong, compact build. They have a dense but short coat. Some people may mistake...

More related

How to Keep Cats Off Your Car: 16 Vet Approved Ideas

Though we all love our furry friends, there is one place we do not want them to hang out: on our cars. Cats...

Can Cats Eat Weed? Vet-Approved Facts & Safety Guide

If you have your medical license, you may have wondered if you can share your marijuana with your kitty. Marijuana, also known as...

How to Tell if Your Bengal Cat is a Mix: 9 Vet-Approved Ways

Bengals are among the most popular cats worldwide and are adored by cat enthusiasts. They are a beautiful hybrid mix of Asian Leopard...

Megacolon in Cats: Signs, Causes, Treatment & Prevention (Vet Answer)

You’re likely quite familiar with your cat’s litter box habits. After all, you need to regularly scoop and clean the box, so you...

Keep reading

Do Cats Like It When You Boop Them? Understanding Your Furry Friend

Booping a cat is the ultimate way to ask a cat’s permission to give them some love. It generally involves taking one finger, touching your cat’s nose, and then holding it out for a cat to investigate. Some, but not...

Can Cats Eat Grapefruit? Vet Approved Health Guide & FAQ

Cats can safely eat a variety of fruits as occasional treats but, unfortunately, grapefruit is not one of them. Cats should never eat grapefruit because most parts of this fruit are toxic and even the flesh can upset their stomachs....

Can Cats Eat Grapefruit

How to Tell if Your Cat Has a Tick – 8 Signs to Look For

Ticks are nasty little parasites that feed on blood. They’re in the same category as fleas and mosquitoes and can cause health problems for your cat if left on the body. So, you definitely want to remove a tick as...

cat with tick

10 Best Flea Combs for Cats in 2025 – Reviews & Top Picks

Caring for your feline friend involves more than just feeding them and ensuring they get regular check-ups. One major aspect of pet care is grooming, which includes dealing with pests like fleas that can cause your cat discomfort and health...

flea combing a tabby cat, looking for fleas

What Behavioral Changes Can I Expect from an Older Cat? Vet Verified

If you’ve spent many years with your cat and they’ve suddenly started to act and do things differently, it could be because of their old age. Cats typically have a lifespan of 12–18 years (although some live much longer) and...

Closeup portrait of old calico cat lying down by kitchen on tiled floor in home

7 Best Calming Collars for Cats in 2025 – Reviews & Top Picks

Cats suffering from anxiety and stress can misbehave, act aggressively, and even develop health problems that can include diarrhea. It’s not always easy to help them reduce their anxiety, but many people have had success with calming collars, which use...

cat wearing a purple collar

Do Cats Cry When They’re Sad? Vet Approved Facts & Care Tips

Ask any cat owner if they believe that their cat is capable of feeling emotions, and you’ll likely be met with a resounding yes. Anyone who’s spent time around cats can quickly realize that our feline friends are indeed capable...

crying-cat_Shutterstock_arvitalyaart

Does Aluminum Foil Keep Cats Off Counters? Why it Works & Alternatives

Many cat parents struggle to keep cats off their kitchen counters. Cats love jumping up on counters and, unfortunately, love knocking things off the counter. Plus, let’s be honest: cats walking around where you prepare food for your family isn’t...

a roll of aluminum foil on countertop