- Toxic forms
- Raw, cooked, dried and powdered
- Most potent
- Garlic, and concentrated powders or soup mixes
- Main danger
- Red blood cell damage (Heinz body anemia)
- When signs show
- Stomach upset early, anemia a few days later
- What to do
- Call your vet or a poison line now
Quick answer
No. Onions, garlic, chives, leeks and shallots all belong to the Allium family, and they damage a cat's red blood cells. Cooked, dried and powdered forms are still toxic, and powders are more concentrated than fresh onion. Signs of anemia often take a few days to appear, so call your vet or a pet poison line as soon as you know your cat ate any, even if they seem fine.
Can cats eat onions? No. Onions and their relatives are toxic to cats in every form, and cats are more sensitive to them than dogs or any other species. The onion family, called Allium, includes onion, garlic, chives, leeks, shallots and scallions (green onions). Pet Poison Helpline data reported by VCA Animal Hospitals put onion-family foods among the top ten cat poisonings of 2023.
The tricky part is timing. A cat can seem completely normal for several days while its red blood cells are being damaged. That’s why you should call as soon as you know your cat ate some, not when signs appear.
Why are onions and garlic toxic to cats?
Onion-family plants contain sulfur compounds. Chopping, cooking and chewing release them, and bacteria in the gut release more. Once absorbed, they damage the hemoglobin inside red blood cells, the part that carries oxygen.
The damaged hemoglobin clumps into small lumps called Heinz bodies. The body sees those cells as faulty and destroys them faster than it can replace them. The result is Heinz body anemia: too few red blood cells to carry enough oxygen around the body.
Cats are especially at risk. Pet Poison Helpline explains that cats rely heavily on an antioxidant called glutathione to protect their red blood cells, which leaves them less able to cope with these compounds. Merck Veterinary Manual describes cats as the most susceptible species.
Can cats eat garlic?
No. Garlic is even more dangerous than onion. According to Merck Veterinary Manual, garlic is 3 to 5 times more toxic than onion. That includes fresh cloves, garlic powder, garlic salt, garlic butter and garlic bread.
Chives, leeks, shallots and scallions carry the same compounds. Merck notes that garlic and onion cause most cases, but the rest of the family can poison cats too, so treat them the same way.
Is cooked onion or onion powder still toxic?
Yes. Cooking, frying, drying or powdering doesn’t remove the harmful compounds. Merck Veterinary Manual reports poisoning in cats and dogs after eating raw, cooked, dehydrated and granulated onion and garlic, and in cats after less than a teaspoon of cooked onion.
Concentrated forms are the biggest worry. Merck notes that poisoning is most often linked to dehydrated flakes, powders and dry onion soup mixes. Pet Poison Helpline estimates that one teaspoon of onion powder is about as potent as 5 ounces of fresh onion, roughly one small onion.
Onion and garlic hide in a lot of human food:
| Food | Why it’s a risk |
|---|---|
| Onion or garlic powder, flakes, salt | Highly concentrated |
| Dry onion soup mix | Highly concentrated |
| Soups, stock, broth and gravy | Often made with onion or garlic, sometimes as powder |
| Baby food | Some meat baby foods contain onion powder |
| Deli meats, ham, sausages | Often seasoned with garlic or onion |
| Pizza, pasta sauce, curry, stir-fry | Usually contain onion or garlic |
| Tuna salad, meatloaf, burgers | Often mixed with onion |
| Garlic bread, garlic butter | Concentrated garlic |
Never use broth or gravy to tempt a cat to eat unless you’ve checked the label. Our what can cats eat? tool lists safer foods to share.
Is baby food with onion powder safe for cats?
Not if it contains onion powder. Meat baby food is sometimes used to tempt a sick cat that has stopped eating, so this matters.
In a 1998 study from the University of California, Davis, published in the Journal of the American Veterinary Medical Association, cats fed baby food containing onion powder developed high numbers of Heinz bodies in their red blood cells. In a second part of the study, the diet with the most onion powder lowered the cats’ red blood cell levels. The researchers concluded that baby food containing onion powder should be avoided for cats, especially when cats eat a lot of it.
Before using any baby food, read the full ingredient list. Look for onion powder, garlic powder, and vague terms like “seasoning” or “natural flavors”. If you’re unsure, ask your vet for a safer option.
What are the signs of Heinz body anemia in cats?
In the first day, some cats have an upset stomach: nausea, vomiting or diarrhea. Many show nothing at all.
The anemia comes later. Merck Veterinary Manual explains that Heinz bodies form within 24 hours and peak at about 72 hours, and the red blood cells usually break down 3 to 5 days after eating. Signs are generally not seen until a lot of cells have been lost. Watch for:
- low energy or weakness
- not eating
- pale or yellow gums
- fast or heavy breathing
- a fast heart rate
- tiring quickly or hiding
- red or brown urine
- collapse
Red or brown urine means broken-down red blood cells are passing through the kidneys, which can injure them.
| Sign | What to do |
|---|---|
| Ate onion or garlic, no signs yet | See vet soon Call your vet or a poison line now |
| Vomiting or diarrhea after eating onion or garlic | See vet soon See a vet today |
| Weakness, pale or yellow gums, fast breathing, red or brown urine, collapse | Emergency Go to an emergency vet now |
To check gum color, gently lift your cat’s upper lip. Healthy gums are pink. White, very pale or yellow gums need a vet.
My cat ate onion or garlic: what should I do?
- Take away the food and anything else your cat could reach.
- Gather the details. What food was it? Did it contain fresh onion, garlic, powder or a soup mix? How much is missing, and when did it happen? Keep the package or recipe.
- Call your vet or a pet poison line. ASPCA Animal Poison Control and Pet Poison Helpline both answer 24 hours a day and charge a consultation fee.
- Don’t make your cat vomit at home. VCA Animal Hospitals warns that there are no over-the-counter products that safely make cats vomit, and salt or hydrogen peroxide can poison or injure a cat.
- Keep watching for several days. Anemia can take that long to show. Check gum color and energy each day, and go in if anything changes.
If you’re not sure how urgent your cat’s signs are, try our should I go to the vet? check or see the cat emergency guide.
How do vets treat onion and garlic poisoning?
If your cat ate onion or garlic recently, your vet may give a medicine at the clinic to make your cat vomit, and sometimes activated charcoal. Your vet will decide whether that’s useful.
Diagnosis relies on what your cat ate, the signs and blood tests that look for Heinz bodies and anemia. IV fluids help protect the kidneys. A cat with severe anemia may need oxygen or a blood transfusion, which means a hospital stay. Your vet chooses the treatment and any medicine doses.
Treatment for severe anemia can be expensive. See what an emergency vet costs for cats so you know what to expect, and use our 24-hour vet finder if your clinic is closed.
How do I keep my cat safe from onions and garlic?
- Don’t share plates, leftovers, gravy or sauces with your cat.
- Keep onions, garlic and spice jars in closed cupboards.
- Clear chopping boards and counters straight after cooking.
- Check the label on any broth, baby food or human food before offering it.
- Give treats made for cats, or plain cooked meat or fish with nothing added.
Not sure about a food? Snap a photo with our food scanner or browse our is it safe for cats? guides, including can cats eat chocolate and can cats eat tuna.
Frequently asked questions
Is a small amount of onion OK for cats?
Don't assume so. Cats are more sensitive to onions than any other species, and poisoning has been reported after less than a teaspoon of cooked onion. Call your vet or a poison line and tell them what your cat ate. They'll tell you whether it needs treatment.
Can cats eat chicken or tuna cooked with onion or garlic?
No. The onion or garlic in the food is the problem, and cooking doesn't make it safe. Plain meat or fish with nothing added is the only safe way to share.
Can cats eat baby food?
Only if the label shows no onion or garlic in any form. A study of cats fed baby food containing onion powder found red blood cell damage. Check for onion powder, garlic powder and vague terms like seasoning or natural flavors, and ask your vet before using it.
Can onion poisoning in cats show up days later?
Yes. Damage to red blood cells starts within a day, but the cells usually break down 3 to 5 days after eating. Weakness, pale gums and fast breathing may not appear until then.
Sources
- Merck Veterinary Manual: Garlic and onion (Allium spp) toxicosis in animals
- Robertson JE, Christopher MM, Rogers QR. Heinz body formation in cats fed baby food containing onion powder. J Am Vet Med Assoc. 1998;212(8):1260-1266
- Pet Poison Helpline: Onions
- Pet Poison Helpline: Feline safety
- ASPCA Animal Poison Control: People foods to avoid feeding your pets
- VCA Animal Hospitals: Household hazards, toxic hazards for cats
Written by the CatsMed Team from the sources above. This guide isn’t reviewed by a veterinarian and isn’t a substitute for one. See how we research.
