Colin FosterBy Colin Foster

Updated November 2026

If you are asking why does my cat have diarrhoea, the short answer is that it is usually caused by diet changes, intestinal parasites, stress or a mild stomach upset. Most cases clear up within a day or two. This guide walks you through the likely causes, what to do at home, and the signs that mean you should call a veterinarian right away.

Common Causes of Diarrhoea in Cats

Diarrhoea means stool that is loose, watery, or more frequent than normal. The most common triggers include:

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  • Sudden food changes. Switching brands or flavors too quickly can upset the gut. Cats need roughly 7 to 10 days to adjust to a new diet.
  • Eating something unusual. Grass, houseplants, string, human food, or spoiled food can all cause loose stools.
  • Intestinal parasites. Roundworms, hookworms, tapeworms, Giardia and coccidia are frequent culprits, especially in kittens and outdoor cats.
  • Stress. Moving house, a new pet, boarding, or a new baby can trigger stress colitis.
  • Infections or inflammatory bowel disease. Bacterial or viral infections and chronic conditions are more likely if diarrhoea lasts longer than a few days.

What to Check Before Calling the Vet

Before deciding how urgent the problem is, take a few minutes to observe your cat and note the following:

  1. How many episodes have happened in the last 24 hours, and whether stool is watery, soft, or has blood or mucus.
  2. Whether your cat is still eating, drinking, and using the litter box normally.
  3. Any recent changes in food, treats, plants, medications or environment.
  4. Whether other pets in the home have similar symptoms.
  5. Your cat’s deworming and flea prevention history.

Write these details down. They help your vet narrow the cause much faster.

Home Care for Mild Diarrhoea

For a healthy adult cat with one or two loose stools and no other symptoms, you can usually manage at home for up to 24 hours:

  • Make sure fresh water is always available. Dehydration is the main risk.
  • Withhold new foods and treats, but do not starve your cat. Offer a small amount of their regular food if they are hungry.
  • Avoid giving human anti-diarrhoeal medicines unless a vet tells you to. Many are toxic to cats.
  • Keep the litter box clean so you can monitor stool changes.

If the diarrhoea continues beyond 24 to 48 hours, return to a normal diet gradually over several days if your cat is otherwise well.

When Diarrhoea Needs a Vet Visit

Call your veterinarian promptly if you notice any of the following. Kittens, senior cats, and cats with chronic illness should be seen sooner.

Sign What to do
Diarrhoea lasting more than 48 hours Book a vet visit
Blood, black stool, or mucus Contact your vet the same day
Vomiting along with diarrhoea Contact your vet the same day
Lethargy, weakness, or hiding Seek urgent care
Dehydration (dry gums, skin that stays tented) Seek urgent care
Refusing food for more than 24 hours Contact your vet the same day

Fecal tests, bloodwork, and deworming are often needed to find the cause. A vet can also prescribe treatment if parasites or infections are confirmed. Always consult a veterinarian before giving any medication to your cat.

Common Mistakes to Avoid

  • Switching diets abruptly when the stomach is already upset.
  • Giving over-the-counter human medicine without vet approval.
  • Ignoring recurring loose stool, which can signal a chronic problem.
  • Skipping regular parasite prevention for indoor-outdoor cats.
  • Waiting too long when a kitten or senior cat has diarrhoea, since they dehydrate faster.

A stool sample is often the fastest route to a diagnosis, so a clean, sealable container and disposable gloves are worth keeping on hand. Owners of multi-cat homes also find a second litter box helpful for tracking which cat is affected.

  • Sealable collection containers for stool samples, which make it easy to bring a fresh sample to the clinic. View on Amazon
  • Disposable nitrile gloves for safe handling and cleanup of loose stool. View on Amazon

FAQ

Can stress really cause diarrhoea in cats?

Yes. Stress colitis is a recognized condition in cats, often linked to moving, boarding, or changes in the household. Symptoms usually improve once the stressor is reduced, but a vet should still rule out other causes.

Is it safe to give my cat plain rice or pumpkin for diarrhoea?

Small amounts of plain cooked food can be offered for a short time, but cats are obligate carnivores and need meat-based nutrition. Check with your vet before using home remedies, especially for kittens.

How long is diarrhoea in cats normally contagious?

It depends on the cause. Parasites like Giardia can spread to other pets and people, so wash hands after cleaning the litter box and separate affected animals until your vet confirms the diagnosis.

Conclusion

Most cases of cat diarrhoea come from diet changes, mild stress, or parasites and resolve with simple home care. Watch closely for blood, vomiting, lethargy, or symptoms lasting more than two days. When in doubt, call your veterinarian, because early testing prevents small problems from becoming serious ones.

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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.