Updated October 11, 2026. Fact-checked against veterinary sources; review by a licensed veterinarian is in progress. See our editorial policy.
Quick answer: Mild diarrhea in an otherwise bright, eating adult cat often settles within a day or two. See a vet if it lasts more than 48 hours, keeps coming back, or comes with vomiting, blood, lethargy, or poor appetite. Kittens, seniors, and cats with health conditions need care sooner because they dehydrate quickly.
Signs to watch
- Soft or watery stool, or more frequent trips to the litter box
- Straining or mucus in the stool
- Accidents outside the box
- Blood in the stool
Common causes
- Sudden diet changes or new treats
- Intestinal parasites such as worms, Giardia, or coccidia
- Stress
- Infections
- Inflammatory bowel disease or intestinal lymphoma in older cats
- Hyperthyroidism
Go to a vet or emergency clinic right away if
- Diarrhea with repeated vomiting
- Lethargy, weakness, or hiding
- Not eating for more than a day
- Large amounts of blood, or black tarry stool
- Signs of dehydration: sticky gums, sunken eyes
- A kitten with diarrhea and lethargy
Safe home care while you arrange a visit
- Keep fresh water available
- Offer small meals of the usual food or a vet gastrointestinal diet
- Keep the litter box clean and note stool changes
- Take a photo of the stool and bring a fresh sample to the vet
What to avoid
- Human anti-diarrhea medicines such as Pepto-Bismol or loperamide
- Milk
- Withholding food for long periods, which risks fatty liver disease
Can you ask a vet online about this?
Online vet services can be helpful for deciding how urgent a problem is, getting general advice, and follow-up questions. But they have limits:
- A vet can’t examine your cat, listen to the heart and lungs, or run tests over video
- In many US states, a vet must have examined your cat in person before prescribing medication. Rules vary by state and are changing
- For any emergency sign listed above, go directly to an emergency clinic rather than waiting for an online reply
Have your cat’s age, weight, medications, and photos or video of the problem ready to make any consultation more useful.
More: IBD in cats and coccidia in cats.
Sources
- Merck Veterinary Manual: Diarrhea in small animals
- Cornell Feline Health Center: Diarrhea in cats
- Companion Animal Parasite Council (CAPC): Guidelines
This article is for general education and is not a substitute for care from your own veterinarian. Learn about The Pet Vet and our editorial policy.