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My 3-year-old cat with a sensitive stomach ate two chocolate chip cookies and now has diarrhoea. Could this be an allergy?

Cats · Food safety

Last reviewed: 2026-09-05 · Reference ranges: ASPCA, Pet Poison Helpline & Merck Veterinary Manual

Short answer

It's more likely an intolerance or mild toxicity, not a classic allergy. The high fat and sugar in cookies can upset a cat's stomach, and chocolate chips add a toxic element. Watch for further signs like vomiting, restlessness, or increased diarrhoea, as these could point to chocolate poisoning. Offer fresh water, withhold food for a few hours to let the gut settle, and call your vet if the diarrhoea persists or she seems lethargic.

Cookies — Food safety facts

Feed with care · Cats · full breakdown on the linked food page

Same traps as cake — chocolate chips, raisins, and sugar-free versions with xylitol.

Dogs and cats carry the same rating (Feed with care), so the notes below hold for either pet.

Cookies is not poisonous to cats, but it is easy to over-feed. Rich fat, salt or seasoning can bring on vomiting or diarrhoea within a day, and repeated large portions are a recognised trigger for pancreatitis.

If it ate some before you noticed, watch for vomiting, diarrhoea, loss of appetite, unusual tiredness or a painful, swollen abdomen over the next 24 hours. A one-off small amount in a healthy adult usually passes with water and rest; repeated exposure, a puppy or kitten, a senior, or a pet with an ongoing illness is a reason to call your vet the same day.

Why these cautions matter

Even a gram or two of xylitol can trigger a sharp drop in a dog's blood sugar, and larger exposures go on to damage the liver.

Theobromine is the part that hurts. Pets clear it far more slowly than people do, so it builds up and reaches the heart and nervous system.

Grapes and raisins are linked to kidney failure in dogs, and no safe amount is reliable — some pets react after only a few.

Added sugar brings empty calories, and over months that means weight gain and dental disease — both far harder to undo than to avoid.

The full verdict, portion guidance and serving notes are collected on the Cookies food facts page.

Open the full food page: Cookies food facts →