Colin FosterBy Colin Foster

Updated November 2026

If you are asking why does my cat have diarrhea, the short answer is that most cases come from diet changes, stress, parasites, or something your cat ate that disagreed with its stomach. This guide walks you through the likely causes, what you can safely do at home for a mild case, and the red flags that mean you should call your veterinarian right away.

Common Causes of Feline Diarrhea

Diarrhea is a symptom, not a disease, so the cause matters. Most episodes fall into a few categories:

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  • Sudden food changes. Switching brands or flavors too fast can upset the gut. A transition should take 7 to 10 days, mixing a little more of the new food each day.
  • Dietary indiscretion. Cats that eat grass, houseplants, string, or table scraps often develop loose stool.
  • Intestinal parasites. Roundworms, hookworms, Giardia, and coccidia are common, especially in kittens and outdoor cats.
  • Stress. Moving, a new pet, boarding, or a change in routine can trigger stress colitis.
  • Infections or illness. Bacterial or viral infections, pancreatitis, inflammatory bowel disease, and kidney or thyroid problems can all show up as diarrhea.
  • Medications or toxins. Some antibiotics and certain household chemicals can cause digestive upset.

What to Do at Home for a Mild Case

If your cat is bright, eating, drinking, and has had only one or two loose stools, you can usually monitor at home for up to 24 hours. Follow these steps:

  1. Withhold the new food or treat you introduced recently.
  2. Offer small, frequent meals of a bland, easily digested food. Many veterinarians suggest a prescription intestinal diet or a short-term plain diet, but ask your vet before using home recipes.
  3. Make sure fresh water is always available. Consider a wet food or a little low-sodium broth to boost fluid intake.
  4. Keep the litter box clean so you can track stool changes. Note color, consistency, and whether there is blood or mucus.
  5. Watch for improvement. Firmer stool within a day or two is a good sign.

Signs You Need a Vet Right Away

Some symptoms should not wait. Contact your veterinarian promptly if you notice any of the following:

  • Diarrhea lasting more than 24 to 48 hours, or any diarrhea in a kitten, senior cat, or cat with health conditions
  • Blood, black tarry stool, or large amounts of mucus
  • Vomiting, refusing food, or lethargy
  • Weight loss, dehydration (skin that stays tented when lifted gently), or pale gums
  • Straining, crying in the litter box, or a painful belly

Your vet may run a fecal test, bloodwork, or both. Parasites are often identified from a stool sample, and that is a quick, inexpensive way to rule out a treatable cause.

Preventing Diarrhea in Your Cat

Good habits lower the odds of repeat episodes. Keep food changes gradual, schedule regular fecal checks and deworming as your vet recommends, and keep toxic plants and string-type toys out of reach. Reduce stress where you can by keeping routines predictable and giving your cat quiet hiding spots. If you are working on litter habits or other behavior issues at the same time, our article on Why Cats Stop Using the Litter Box and How to Respond covers how to separate litter problems from medical ones.

Common Mistakes to Avoid

  • Giving human anti-diarrhea medications without veterinary guidance. Many are toxic to cats.
  • Switching foods repeatedly while the stomach is still upset.
  • Assuming a single soft stool is an emergency, or ignoring diarrhea that keeps coming back.
  • Skipping the fluid check. Dehydration is the main risk with diarrhea.
  • Overlooking appetite changes. A cat that stops eating needs attention, so see Why Your Cat’s Appetite Has Suddenly Changed for related signs.

A clean, shallow litter tray makes it much easier to see stool changes and track how often your cat goes. A digital kitchen scale helps you monitor weight loss over time, which matters if the diarrhea lingers.

  • A shallow, uncovered litter pan lets you check stool quickly and easily. View on Amazon
  • A digital pet scale helps you track weight week to week so you can spot losses early. View on Amazon

FAQ

Can stress alone cause my cat to have diarrhea?

Yes. Stress colitis is a recognized cause in cats, often following a move, a new household member, or a change in routine. If the diarrhea resolves once the environment settles, stress is a likely culprit, but your vet should still rule out other causes.

Is it safe to give my cat plain pumpkin for diarrhea?

Plain canned pumpkin (not pie filling) is sometimes recommended in small amounts, but ask your veterinarian first. Dosing depends on your cat’s size and condition, and it is not appropriate for every case.

How long should cat diarrhea last before I call the vet?

If diarrhea continues beyond 24 to 48 hours, or sooner if your cat is a kitten, senior, or shows other symptoms, call your veterinarian. Prompt evaluation is safer than waiting it out.

Conclusion

Cat diarrhea has many possible causes, from a sudden diet change to parasites or a more serious illness. Track the stool, keep your cat hydrated, and act quickly on warning signs like blood, vomiting, or lethargy. When in doubt, a fecal test and a vet visit will give you a clear answer.

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Colin Foster

About Colin Foster

Colin Foster is part of our editorial team and reviews and edits our cats guides, checking product details against manufacturer specifications and owner feedback.