Cat Diarrhea: When to Worry & What to Do
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A single bout of soft stool is often nothing serious and may resolve on its own in a day or two. You should worry — and call your vet — if diarrhea lasts more than a couple of days, contains blood, comes with vomiting, lethargy, or appetite loss, or if your cat is a kitten, senior, or looks dehydrated. Dehydration is the main danger, and it develops faster in small or young cats.
When to call the vet
Contact your vet promptly if your cat's diarrhea comes with any of these: it lasts more than about 48 hours, contains blood (red streaks or black tarry stool), or comes with repeated vomiting, lethargy, not eating, a painful belly, or signs of dehydration. Kittens, senior cats, and cats with other illnesses should be seen sooner — they dehydrate quickly and have less reserve.
For an otherwise bright, active adult cat with one or two soft stools and no other signs, it's usually reasonable to watch closely for a day. The judgment call is about the whole picture, not the stool alone.
Common causes
Diarrhea is a symptom, not a disease, and the list of causes is long. Common ones include:
- Dietary changes or indiscretion — a new food switched too fast, table scraps, or eating something they shouldn't.
- Intestinal parasites — especially in kittens and outdoor cats.
- Infections — viral or bacterial.
- Stress — travel, a move, or changes at home.
- Food intolerance or allergy.
- Chronic conditions — inflammatory bowel disease, hyperthyroidism, kidney disease, or other systemic illness, especially when diarrhea is ongoing.
Reading the clues
The character of the diarrhea can hint at where the problem is, which helps your vet:
| What you see | What it may suggest |
|---|---|
| Large volume, watery | Small-intestine origin |
| Small amounts, frequent, with straining or mucus | Large-intestine (colon) origin |
| Bright red blood | Lower tract; note it for your vet |
| Black, tarry stool | Digested blood from higher up — call your vet |
You don't need to diagnose it yourself, but noting these details — and bringing a fresh stool sample — speeds up the vet's work.
Home care for mild cases
For a mild case in an otherwise healthy adult cat, and only if your vet agrees:
- Keep fresh water available — hydration is the priority.
- Offer a bland, easily digestible diet as your vet recommends; don't withhold food from cats for long, as fasting can be risky for them.
- Avoid sudden diet changes and rich treats while things settle.
- Don't give human anti-diarrheal medicines — some are toxic to cats.
If it isn't clearly improving within a day or two, or any red-flag sign appears, stop watching and call your vet.
Tracking helps you and your vet
Diarrhea that comes and goes is one of the trickiest things to describe from memory. Was it three days ago or last week? Every day, or twice this month? Logging each episode — the date, consistency, any blood or mucus, and what your cat ate — turns a vague worry into a clear pattern. For chronic or recurring diarrhea especially, that record helps your vet distinguish a one-off upset from an ongoing condition, and shows whether a diet change actually helped. Pair it with tracking your cat's weight, since steady weight loss alongside diarrhea points toward a deeper problem.
Turn on-and-off diarrhea into a clear picture
Tavi lets you log stool changes, appetite and weight over time, so recurring diarrhea becomes a pattern your vet can act on instead of a guess. Free for your first pet.
Frequently asked questions
How long is it normal for a cat to have diarrhea?
A single mild bout often resolves within a day or two in an otherwise healthy adult cat. Diarrhea lasting more than about 48 hours, or that keeps recurring, warrants a vet visit. Kittens, senior cats and cats with other health issues should be seen sooner because they dehydrate quickly.
When should I worry about my cat's diarrhea?
Worry if it lasts more than a couple of days, contains blood or is black and tarry, or comes with vomiting, lethargy, appetite loss, a painful belly, or signs of dehydration. These suggest something beyond a simple upset. Very young, senior, or already-ill cats need earlier attention.
What can I give my cat for diarrhea at home?
For a mild case, and ideally with your vet's okay, keep fresh water available and offer a bland, easily digestible diet, without withholding food for long since fasting is risky for cats. Never give human anti-diarrheal medications, as some are toxic to cats. If it doesn't improve quickly, call your vet.
Can stress cause diarrhea in cats?
Yes. Stress from travel, a move, new pets or changes at home can upset a cat's digestion and cause diarrhea. It usually settles as the cat adjusts, but stress-related diarrhea that persists, or comes with other signs, still deserves a vet check to rule out other causes.
Should I take a stool sample to the vet?
Yes, a fresh stool sample is very helpful, especially for checking for intestinal parasites, which are a common cause of diarrhea. Collect a fresh sample close to your appointment. Also note the color, consistency and frequency, and whether there's blood or mucus, to help your vet.
Tavi's guides are informational and not a substitute for professional veterinary advice, diagnosis or treatment. When in doubt, call your veterinarian. Sources: Cornell University Feline Health Center; Merck Veterinary Manual; VCA Animal Hospitals; American Association of Feline Practitioners (AAFP)