Quick answer
Cat diarrhea that lasts a day or two in an adult cat that's still eating, drinking and acting normally is often caused by a diet change or stress and can be watched at home. See a vet if it lasts more than 48 hours, keeps coming back, or comes with vomiting, lethargy or not eating. Kittens, black tarry stool and a lot of blood in the stool need a vet the same day.
Cat diarrhea is common, and most cases pass on their own. If you’re not sure how urgent it is, our symptom check will tell you whether to go now, call today or book a visit this week.
What causes diarrhea in cats?
Diarrhea means stool that’s looser, more frequent or larger in volume than normal. It may also look gray or yellow and smell worse than usual. Vets sort it into sudden (acute) diarrhea that lasts a few days, and chronic diarrhea that goes on for weeks or keeps coming back.
Sudden cases are often linked to food or stress. Chronic cases usually come from a problem in the gut itself, like inflammation, infection or a tumor. Some come from illness elsewhere in the body, such as an overactive thyroid, kidney disease or liver disease.
| Cause | Common signs | Urgency |
|---|---|---|
| Diet change or new treats | Started within a few days of a new food, otherwise well | Monitor |
| Stress (move, new pet, boarding) | Short-lived, cat still eating | Monitor |
| Intestinal parasites (worms, Giardia, coccidia) | Common in kittens and new cats, mucus, weight loss | See vet soon |
| Food intolerance or allergy | Loose stool on and off for weeks, sometimes vomiting | See vet soon |
| Inflammatory bowel disease or lymphoma | Chronic diarrhea or vomiting, weight loss, often middle-aged or older | See vet soon |
| Hyperthyroidism | Older cat, eating more but losing weight, drinking more | See vet soon |
| Panleukopenia (feline distemper) | Unvaccinated kitten, severe diarrhea, vomiting, fever | Emergency |
| Toxins or a swallowed object | Vomiting, belly pain, not eating | Emergency |
Your vet may also ask whether your cat strains and passes small amounts often, or passes large amounts a few times a day. Frequent small stools with mucus usually point to the large intestine (colitis). Large, watery stools and weight loss usually point to the small intestine.
What does blood in stool mean in a cat?
It depends on the color. Bright red blood or streaks of red with mucus usually come from the lower bowel or rectum. That’s often from colitis, straining or parasites. A small streak in a cat that’s otherwise well should be checked by your vet within a day or two.
Black, tarry stool is different. It usually means digested blood from higher up in the gut, such as a stomach ulcer, and it needs a vet the same day. So does a large amount of fresh blood, or blood in the stool of a kitten or a cat that’s weak, vomiting or not eating.
Take a photo of the stool, or bring a fresh sample in a clean bag. It helps your vet a lot.
When should I worry about cat diarrhea?
Watch an adult cat at home only if they’re still eating, drinking, playing and using the litter box normally. See your vet if:
- Diarrhea lasts more than 48 hours
- It keeps coming back over weeks or months
- Your cat is losing weight
- Your cat is also vomiting, eating less or seems tired
- Your cat is a senior or has another illness, like kidney disease or diabetes
Kittens can become dehydrated within hours, so a kitten with diarrhea should see a vet the same day. Diarrhea and vomiting together raise the risk of dehydration in cats of any age. If your cat has also stopped eating, read our guide to a cat not eating.
How is diarrhea in cats diagnosed and treated?
Your vet will start with questions about diet, recent changes and how long it’s been going on, then a physical exam. Common next steps include a fecal test for parasites, bloodwork and sometimes x-rays or an ultrasound. Chronic cases may need a diet trial or, occasionally, biopsies of the gut.
Treatment depends on the cause. It may include a deworming medicine, a highly digestible or hypoallergenic diet, fiber, a feline probiotic, fluids for dehydration or, for chronic inflammation, longer-term medication. Your vet will set any doses for your cat.
| Service | Typical cost |
|---|---|
| Exam | $55 – $110 |
| Fecal test | $30 – $80 |
| Bloodwork panel | $120 – $260 |
| Abdominal x-rays | $150 – $350 |
| Fluids under the skin | $40 – $90 |
Emergency clinics usually charge more. For a full breakdown, see how much a cat vet visit costs.
What diarrhea home care is safe for cats?
Diarrhea home care is only for adult cats with mild loose stool who are otherwise acting normally. If anything in the red box applies, skip this and call a vet.
- Keep water available. Put out fresh water in a few places. Adding a little water to wet food helps too.
- Don’t fast for long. Unlike dogs, cats shouldn’t go without food for long. Offer small, frequent meals.
- Go bland. Your vet may suggest a prescription gastrointestinal diet for a few days. Ask them before switching to home-cooked food.
- Undo recent changes. If you changed food or added new treats, go back to what worked. Make future food changes gradually over 7 to 10 days.
- Keep a record. Note how often your cat goes, what the stool looks like and whether it contains blood or mucus.
- Keep the litter box clean. Scoop often, and wash your hands after, since some parasites can spread to people.
Leave human stomach remedies in the cabinet. The salicylate in Pepto-Bismol behaves like aspirin in a cat’s body, which makes it toxic, and other human anti-diarrhea medicines can cause serious side effects. If you want to support your cat’s gut, ask your vet about probiotics made for cats.
If the diarrhea hasn’t improved in 48 hours, call your vet. For other common signs and what they mean, browse our cat symptoms guides.
Frequently asked questions
How long can a cat have diarrhea before going to the vet?
An adult cat that's otherwise well can be watched for 24 to 48 hours. If it lasts longer, keeps returning, or your cat is also vomiting, not eating or tired, see your vet. Kittens and senior cats should be seen sooner.
Should I stop feeding my cat if they have diarrhea?
Don't withhold food for more than a few hours without your vet's advice. Cats that stop eating can develop a serious liver problem called hepatic lipidosis. Small, frequent meals of a bland or vet-recommended diet are usually better.
Can I give my cat Pepto-Bismol or Imodium for diarrhea?
No. Pepto-Bismol contains bismuth subsalicylate, a close chemical cousin of aspirin, and it's toxic to cats. Imodium and other human anti-diarrhea medicines can also cause problems, so give nothing unless your vet tells you to.
Why does my cat have diarrhea but is acting normal?
A recent food change, a new treat, mild stress or eating something from the trash are common causes. If loose stool keeps coming back over weeks, it can be a sign of food intolerance, parasites or inflammatory bowel disease.
Sources
Written by the CatsMed Team from the sources above. This guide isn’t reviewed by a veterinarian and isn’t a substitute for one. See how we research.
