Can Dogs Have Onions? Risks & Toxicity of Onions for Dogs

Pet care & safety

Red onions, yellow onions, and white onions can all be harmful to dogs. But regardless of the onion's color, how much onion is toxic to dogs? Even small amounts can be dangerous, so it's important to keep onions out of your dog's reach.

Onions in their various forms are favorite flavor boosters for some humans’ tastebuds. These versatile vegetables can be eaten in nearly every form and added to nearly every dish--every dish, that is, except your dog’s food bowl. Onions are actually toxic for dogs to consume, and when eaten in large enough amounts can cause significant issues. So, whether you’re looking to sneak your dog a taste of your dinner or are into home cooking your dog food, it’s important to know that onions are bad for dogs. 

What Makes Onions Toxic to Dogs? 

Onions, and other members of the Allium, contain a compound called N-propyl disulfide which causes damage to the membranes of a dog’s red blood cells. This damage makes the membranes fragile and more likely to burst. You can probably guess that fragile, bursting red blood cells are a problem, especially if a lot of them are affected. 

Eating onions can lead to a condition called Heinz body hemolytic anemia which is a medical way of saying a reduced number of red blood cells due to red blood cell destruction. The Heinz body part refers to little bundles of hemoglobin that can be found when looking at an affected animal’s blood under the microscope. They just help a veterinarian clue in that the cause of the anemia may be due to eating something like onions.  

It's also important to know that it’s not just onions that are a problem. All members of the Allium family, including garlic, leeks, and chives, can do the same thing. 

Forms of Onions That are Toxic to Dogs 

You now know why onions are a no-no on your dog’s dinner menu, but can dogs eat onions in other forms? The answer is no. All variations of onions can affect your dog’s health. That includes raw or cooked onions, dried onions and powdered or minced onions. Even green onions make the bad list for dogs. 

The same goes for garlic, chives and leeks. No form of these, even the seasonings prepared from them, are safe for a dog to eat. 

How Much Onion is Toxic to Dogs? 

The amount of onion that your dog needs to eat to cause problems is going to vary based on your dog’s weight. While some sources suggest that even a small amount like 0.5% of a dog's weight in onions can be harmful, this can be difficult to visualize.

Instead, let’s look at it based on the size of the onion or amount of onion powder a dog would need to eat. For a dog around 10 pounds, about 3/4 of a tablespoon of chopped onion or 1/3 teaspoon of onion powder can lead to signs. For dogs around 30 pounds, it would take 1/3 cup chopped onion or 1 teaspoon onion powder and for dogs around 60 pounds, you can double those amounts.  

Fortunately, most dogs aren’t going to raid your onion bin and help themselves to a plain, raw onion. The bigger risk of onion toxicity in dogs comes into play when you’re cooking for them or sharing some of your meal. Seasoning your food with onion or garlic powder and then sharing it with your canine companion can make them sick. I have never seen a dog with onion toxicity from eating onions on their own, instead, all the issues have come from eating human foods. 

Signs of Onion Poisoning in Dogs 

The major concern with eating onions or their garlic, chive, and leek relatives is the anemia that may ensue within a few days, but that likely won’t be the first signs you see if your pup gobbles down a bunch of onion or onion powder. Instead, what may show up first is: 

  • Vomiting 

  • Diarrhea 

  • Lethargy 

  • Decreased appetite 

  • Drooling 

  • Abdominal pain 

Then, within 3-5 days, you may see: 

  • Weakness 

  • Pale gums 

  • An increased respiratory rate 

  • Excessive panting 

  • Reddish or brownish urine 


A brown dog is sitting in a raised garden bed surrounded by green onion plants, looking up at a person gently petting its head. This image highlights the importance of keeping dogs away from onions, as they can be toxic to pets.

What to do if Your Dog has Consumed Onions 

If you witness your dog eating onions or onion-containing products contact your vet or the pet poison control hotline immediately. Don’t do any treatments, such as inducing vomiting at home, unless instructed by a veterinarian.  

If your pup ate the onions within a few hours, your vet may induce vomiting in the clinic to try to get as much of the onion out as possible. They may then give activated charcoal in an attempt to absorb what couldn’t be vomiting out. From there, supportive treatment will begin, which may include fluids, anti-emetics, and hospitalization. 

If it’s been longer than a couple of hours since ingestion, your vet will go right to supportive treatment. They will likely run blood tests to check kidney and other organ function and to get a look at your pup’s red blood cells. Fluids or even blood transfusions may be necessary. 

Fortunately, in most mild cases of onion toxicity in dogs, they will recover. Severe toxicity, especially without treatment, may be fatal. That’s why preventing your pup from eating onions in the first place is always the best way to go. 

The High Cost of Onion Poisoning 

While it's important to prevent your dog from ingesting onions, accidents can happen. Onion poisoning can be a costly affair for pet owners. This is where dog pet insurance can be invaluable. The treatment for this condition can vary widely depending on the severity of the case and the necessary medical interventions. Here's a breakdown of potential costs: 

  • Emergency veterinary visit: This is often the first step in treating onion poisoning. The cost can vary, depending on the veterinarian's fees and the location. 

  • Diagnostic tests: To determine the extent of the damage to your dog's red blood cells, your veterinarian may need to conduct blood tests. These tests can add to the overall cost. 

  • Treatment: Depending on the severity of the poisoning, your dog may require treatments such as induced vomiting, activated charcoal, intravenous fluids, or even blood transfusions. These procedures can be expensive. 

  • Hospitalization: In severe cases, your dog may need to be hospitalized for monitoring and treatment. This can significantly increase the cost of care.  

Treatment can vary depending on the severity of the poisoning. The total cost of treating onion poisoning can easily exceed $1,000 or more. This is why investing in pet insurance can provide peace of mind and financial protection in such situations.  

Preventing Onion Poisoning in Dogs 

Again, most dogs aren’t going to seek out and steal plain onions. Instead, they’re more at risk of eating them when consuming human foods, given to them both intentionally and unintentionally. Many human foods contain onions, including savory dishes like chili, pasta sauces, and stir-fries. So, the best prevention is to not feed human foods, especially if you don’t know the full ingredients list, to your pets. You’ll want to store onions and other foods out of reach of your dog as well. Also, keep onions out of homemade dog treats and opt for other flavorings instead. There are lot of dog friendly seasonings that you can use instead, but when in doubt, find out before giving it to your pup. Can dogs eat cinnamon? Yes, in small amounts, so try that flavor instead. 

If you just can’t resist those begging puppy dog eyes, choose safe and healthy foods to share with your pup. Cut up pieces of plain, cooked or raw carrots, green beans, pumpkin, or raw cucumber are much better options. Fruits like apples, bananas, berries, and melons are also good options in moderation. 

If you’re looking for something a little more adventurous in the snack department, you may wonder about nuts. Can dogs eat cashews? While macadamia nuts are toxic, other nuts can be safe in small amounts. Speak to your vet about safe human food options for your pup. 

Dogs Cannot Safely Consume Onions 

Onions may be a household staple, but they aren’t okay to feed to your dog. Onions are actually toxic, and if eaten in high enough amounts, can lead to fairly serious issues including anemia and death. If you see your dog eat onions, just suspect it, or if they are showing any signs of illness, see your vet as soon as possible.  

A dog's love is a precious gift, and it's our responsibility to keep them safe. Understanding what's harmful to them, like onions, is an essential part of being a responsible pet owner. By being mindful of their diet and keeping them away from harmful foods, we can ensure they stay healthy and happy for years to come.