Can dogs eat onions? What you need to know

White dog sat next to two onions that have just been harvested
(Image credit: Getty Images)

There are lots of human foods that dogs love to eat, but can dogs eat onions? The simple here is a hard no - in fact they should be avoided at all costs. 

All parts of the onion are toxic to dogs and consuming them can cause major problems. It’s also true that onion and onion powder can be found in lots of common foods, such as pre-prepared products such as soups, ready meals and baby food.

It’s very important to keep your dog away from onions and any product that may contain them. You will also need to act quickly should your canine companion accidentally consume some. 

Although you’ll probably want your pup’s diet to be made up largely of the best dog food, if you want to share some snacks with your canine pal, be sure to check what human food can dogs eat.

Why are onions bad for dogs?

Onions contain something called N-propyl disulfide which can cause anemia in dogs as it attacks your dog’s red blood cells.

It doesn’t take a lot of onion for your dog to become sick. The American Kennel Club estimates that about 100 grams of onion per 20kg of dog is enough to cause problems. That’s about the size of a medium onion. 

Symptoms you might see in your dog include weakness and lethargy, a loss of appetite, pale gums, fainting and urine with a red tinge. You might also see vomiting, a faster heart rate and excessive panting

Onions on a table

(Image credit: Getty Images)

What to do if your dog eats onions 

It’s important to remain calm, but you should try and evaluate exactly how many onions your dog is likely to have ingested. If it’s a couple of small pieces that have fallen from your chopping board (and you have a large dog), while it’s a good idea to be mindful of any of the above symptoms, it’s probably not time to panic yet. 

However, if they somehow managed to chomp their way through an entire bag, or devoured something which contains onions / onion powder in, then it’s best to seek medical advice from your vet as soon as possible. It’s also a good idea to seek help if you’ve got a small dog, and/or you’re not sure exactly how much they might have eaten. 

Your vet will likely look for the above signs, as well as run blood tests to see if there’s any signs of anemia. If you get your dog to the vet quite quickly, your vet will likely induce vomiting, and is likely to keep your dog under careful observation. In some cases, the dog might require a blood transfusion. 

Sadly, in extreme cases, dogs have been known to die from onion poisoning, so it really is important to get help and advice as soon as you possibly can. 


Onions are highly toxic, and even fatal, to dogs and you should do everything you can to make sure your dog doesn’t get to them. 

Make sure to always check the ingredients of any human food you might be tempted to feed your dog too. Most importantly, should your dog accidentally ingest onions, pay close attention to how they react and contact your vet if you’re at all worried.

Amy Davies

Amy Davies is a freelance writer and photographer with over 15 years experience. She has a degree in journalism from Cardiff University and has written about a huge variety of topics over the years. These days she mostly specialises in technology and pets, writing across a number of different titles including TechRadar, Stuff, Expert Reviews, T3, Digital Camera World, and of course PetsRadar. She lives in Cardiff with her dog, Lola, a rescue miniature dachshund.