Short answer: onions, garlic, chives and leeks are the human foods most dangerous to cats. The Merck Veterinary Manual calls cats the most susceptible species and notes poisoning after less than a teaspoon of cooked onion. Chocolate and caffeine, alcohol, raw yeast dough and grapes are also on the list, along with lilies, which aren’t food but can cause fatal kidney failure. If your cat eats any of these, call your vet, ASPCA Animal Poison Control at (888) 426-4435 or Pet Poison Helpline at (855) 764-7661.
Cats are obligate carnivores with a metabolism quite different from dogs, which means some foods that are relatively low-risk for dogs can be more dangerous for cats, and vice versa — the toxic list isn’t identical between species.
What Foods Are Toxic to Cats?
The table combines the ASPCA’s list of people foods to avoid with the Merck Veterinary Manual’s toxicology and nutrition chapters. “How serious” is a general guide; any real exposure is worth a call.
| Food | Toxic compound or problem | What it does to cats | How serious |
|---|---|---|---|
| Onions, garlic, chives, leeks (raw, cooked, powdered) | Sulfur-containing oxidants | Destroy red blood cells, causing anemia days later | Serious; cats are the most sensitive species |
| Lilies (true lilies and daylilies) | Toxin present in every part of the plant | Vomiting, then acute kidney failure; pollen and vase water count | Emergency, any amount |
| Chocolate, cocoa, coffee, tea, energy drinks | Theobromine and caffeine | Vomiting, restlessness, abnormal heart rhythm, tremors, seizures | Dose-dependent; cats rarely eat much |
| Alcohol, including in desserts | Ethanol | Vomiting, incoordination, breathing difficulty, coma | Emergency; absorbed quickly |
| Raw yeast dough | Expanding yeast plus ethanol | Stomach distension and alcohol poisoning | Emergency |
| Grapes and raisins | Tartaric acid is suspected in dogs | Kidney failure reported anecdotally in cats | Treat as an emergency; evidence in cats is limited |
| Milk and dairy | Lactose | Diarrhea and stomach upset | Mild, but best avoided |
| Large amounts of canned tuna | Too little vitamin E | Pansteatitis (painful inflamed body fat) | Serious if fed regularly |
| Raw fish | Thiaminase enzyme | Destroys thiamine (vitamin B1); neurologic signs | Serious if fed regularly |
| Raw eggs | Avidin in whites; bacteria | Biotin deficiency; Salmonella or E. coli | Moderate |
| Liver as a main food | Excess vitamin A | Vitamin A toxicity | Serious if fed regularly |
| Raw meat and bones | Bacteria; sharp fragments | Infection risk for cat and people; mouth or gut injury | Moderate to serious |
| Very salty foods | Sodium | Thirst, vomiting, tremors, seizures | Dose-dependent |
Why Are Onions and Garlic Such a Problem for Cats?
Merck ranks cats as the most susceptible species to Allium poisoning, followed by dogs. The sulfur compounds released when onion or garlic is chopped, cooked or chewed damage red blood cells, and the damaged cells are destroyed, typically 3–5 days after exposure. Poisoning is most often linked to concentrated forms such as dehydrated flakes, powders and dry soup mixes, but Merck reports cases in cats after less than a teaspoon of cooked onion, or 5 g of raw onion per kilogram of body weight.
That makes leftovers a real risk. Gravies, stews, curries, dal with tadka, stuffing and seasoned meat are often built on onion and garlic. If you share home-cooked food with your cat, our guide to caring for a senior desi cat covers which Indian home foods are safe and which, like masala and tadka leftovers, are not.
Why Are Lilies a Hazard Worth Knowing About?
Lilies deserve special mention because the risk is so severe and so commonly underestimated. Pet Poison Helpline says all parts of true lilies (the Lilium genus, including Easter lilies) and of daylilies are toxic to cats, “including any amount of leaf, stem, flower, pollen, vase water, or rhizome,” and that ingestion leads to vomiting, abdominal pain, dehydration and acute kidney failure. If you have cats, not bringing these lilies into the home at all is the safest approach. Other plants called lilies behave differently; lily of the valley, for example, contains heart toxins instead.
Why Is Tuna, Raw Fish or Liver a Problem If It’s “Natural”?
These foods aren’t poisons in small amounts; the danger is a diet built around them. The Merck Veterinary Manual’s chapter on nutritional requirements describes vitamin E deficiency and pansteatitis in cats given large quantities of canned tuna, thiamine deficiency from thiaminase enzymes in raw freshwater fish (cooking and canning destroy them), biotin deficiency from the avidin in raw egg whites, and vitamin A toxicity from feeding only liver. The fix is a complete and balanced cat food, with these foods as occasional extras at most.
Cats also can’t do without animal-based nutrients. The ASPCA notes cats are obligate carnivores that must get taurine from animal sources, which is why vegetarian diets aren’t appropriate for them, and Merck adds that cats, unlike dogs, can’t convert beta-carotene from plants into vitamin A. A food formulated and labeled for cats should be the staple.
Which “Toxic Food” Claims Are Myths for Cats?
- Xylitol: dangerous to dogs, but the Merck Veterinary Manual says dogs are the only domestic species in which xylitol poisoning has been reported and cats are not at risk of the low blood sugar or liver injury it causes. Sugar-free sweets can still contain chocolate or caffeine, so check the label.
- Chocolate: still toxic to cats, but less often a problem. In the ASPCA’s Top 10 Toxins of 2025, chocolate made up 13.6% of calls, mostly involving dogs; cats may sample it but rarely eat large amounts.
- Grapes and raisins: the evidence in cats is thinner than in dogs. Merck notes only anecdotal reports of kidney failure in cats, while Pet Poison Helpline says grapes and raisins can “potentially” harm cats. Treat any ingestion seriously anyway.
What Should You Do If Your Cat Eats Something Toxic?
- Take away what’s left and keep the packaging, plant or recipe.
- Note what, how much and when, and your cat’s approximate weight.
- Call for help now, even if your cat seems normal: your vet or nearest emergency clinic, ASPCA Animal Poison Control at (888) 426-4435, or Pet Poison Helpline at (855) 764-7661. Both hotlines run 24/7; ASPCA says a consultation fee may apply and Pet Poison Helpline charges $89 per incident. In India, call your vet or the nearest 24-hour veterinary hospital.
- Don’t try to make your cat vomit. Pet Poison Helpline says there is no safe way to induce vomiting in cats at home, and hydrogen peroxide can cause serious inflammation and ulcers in a cat’s stomach and esophagus. Vets use injectable drugs for cats when vomiting is appropriate.
- Don’t wait for symptoms. Onion and garlic anemia can take days to appear, and lily kidney damage is treated most successfully early.
Symptom onset is often delayed, and early treatment substantially improves outcomes for most of these toxins. For the list that applies to dogs in the same household, see our guide to human foods toxic to dogs; if you also keep birds, our guide to foods toxic to pet birds covers a different set of risks, including avocado.
This article is for informational purposes only and does not replace guidance from your veterinarian.
Sources
- ASPCA — People Foods to Avoid Feeding Your Pets
- ASPCA — The Top 10 Toxins of 2025, March 2026
- ASPCA — Why Can’t My Cat Be Vegan?, May 2018
- Merck Veterinary Manual — Garlic and Onion (Allium spp) Toxicosis in Animals, September 2024
- Merck Veterinary Manual — Nutritional Requirements of Small Animals, November 2023
- Merck Veterinary Manual — Xylitol Toxicosis in Dogs, June 2025
- Merck Veterinary Manual — Grape, Raisin, and Tamarind Toxicosis in Dogs, September 2024
- Pet Poison Helpline — Lilies and Daylily
- Pet Poison Helpline — Hydrogen Peroxide to Induce Vomiting, May 2026
- Pet Poison Helpline — Veterinarians Warn Pet Owners About Halloween Dangers
