Why?
Potatoes are nightshades. Solanine concentrates in the skin, green patches, sprouts and in raw or poorly stored potatoes; it irritates the gut and, in large amounts, can affect the nervous system. Cooking doesn't fully destroy it, which is why peeling and cutting away anything green matters. Once cooked, the flesh is mostly starch, which does nothing useful for a carnivore.
How much?
A teaspoon of peeled potato, well boiled or steamed and mashed, once in a while. No butter, milk or salt: no seasoned mashed potatoes, fries, chips or au gratin.
The risks
- Raw, green or sprouted potato: toxic solanine
- Vomiting, diarrhea, drooling, lethargy
- Weakness or neurological signs after a large amount of raw potato
- Fries, chips and gratins: too fatty and salty
- Weight gain, since it's mostly starch
Your cat ate some: what now?
A little plain cooked potato is no problem. If your cat ate raw potato, green skin or sprouts, watch it for 24 to 48 hours and call your vet if it vomits, drools, has diarrhea or seems weak. Call right away if it ate a large amount.
Better options
Cooked sweet potato has no solanine, and cooked pumpkin brings fiber with few calories: two simpler options.
Common questions
Can cats eat mashed potatoes?
Only a small spoonful made without butter, milk or salt. Classic mashed potatoes contain dairy and butter that can cause diarrhea, and sometimes garlic.
Can cats eat french fries?
One fry isn't dangerous, but fries are fatty and salty, so don't make it a habit. Just watch for vomiting or diarrhea afterward.
This information is general and does not replace advice from a veterinarian. If your cat has swallowed something toxic, call your vet or an animal poison control center right away, without waiting for symptoms.