Can Cats Eat Onions or Garlic?

No. Onion and garlic are toxic to cats, and cats are more sensitive to them than dogs are. If your cat just ate some, call your vet or a poison line now, even if your cat seems fine: the damage to red blood cells shows up days later.

Why cats are especially at risk

The Merck Veterinary Manual is blunt: “Cats are the most susceptible species, followed by dogs.” The ASPCA agrees (“Although cats are more susceptible, dogs are also at risk”), and Pet Poison Helpline says “certain animal species and breeds are more sensitive to Alliums including cats.”

The ASPCA explains what they do: “Allium species can cause gastrointestinal irritation and red blood cell damage.” Garlic is the stronger of the two: Merck says “garlic is 3–5 times more toxic than onion.”

Then there’s the amount. Merck notes that “toxicosis has been reported in cats after ingesting less than a teaspoon of cooked onions.” That figure comes from Merck alone, but it’s why I treat any amount as a reason to call: for a cat, there’s no amount small enough to wait and see.

Every form counts

Merck says dogs and cats “have been affected after ingesting raw, cooked, dehydrated, or granulated onions and garlic,” and it notes that concentrated forms are the most common cause. In a kitchen, that means:

• Onion and garlic powder in seasonings and rubs
• Food cooked with onion or garlic, even if you can’t see any pieces
• Chives, part of the same family the ASPCA warns about

Keep these out of reach, and check the label before you share any people food with your cat.

Signs, and why they come late

“Hemolysis typically occurs 3–5 days after exposure,” Merck says: that’s when red blood cells break down. The signs Merck lists include lethargy, not eating, fast breathing, a fast heart rate, weakness, tiring easily and jaundice (a yellowish tint). Severe cases can bring blood-tinged urine, collapse and death. Because the anemia is delayed, a cat can look normal for days.

When to call the vet: right now

1. Call your vet or a poison line as soon as you know. In the US, ASPCA Animal Poison Control at (888) 426-4435 is “available 24/7, 365 days a year,” and Pet Poison Helpline is available 24/7 at (855) 764-7661 (a fee may apply).
2. Have the details ready: what your cat ate, roughly how much, when, and your cat’s weight.
3. Don’t wait for signs, and don’t try home treatment. Merck’s guidance favors early decontamination, and that’s your vet’s job.
4. Over the next days, report any of the signs above to your vet, even after a reassuring first call.

Keep the free Pet Poison Emergency Card on the fridge so the numbers are there when you need them. For setting up a new cat’s home, there’s also the free New Cat Checklist.

More on what cats can eat

Dogs face the same risk at a lower sensitivity (onions and garlic for dogs). For the other common kitchen questions, see milk, tuna and dog food, and the new kitten checklist for setting up a safe home.