Cat Throwing Up or Has Diarrhea? What to Do Next
Cat Throwing Up or Has Diarrhea? What to Do Next
By the Humarian Research Team · Updated September 15, 2026
Quick Answer
Occasional vomiting or diarrhea in cats is often something minor — a hairball, a fast diet change, or a mild stomach upset — and it can often be managed at home with a short rest for the gut, a bland diet, and fresh water. But a few symptoms mean you should skip the home remedies and call your vet right away. Once the episode has passed, a daily probiotic can help support your cat's normal digestion going forward.
Call Your Vet Now If Your Cat Has:
- Blood in the vomit or stool
- Vomiting more than once a week, or repeated vomiting/dry heaving that doesn't stop
- Diarrhea or vomiting lasting more than a day or two
- Lethargy, weakness, or decreased appetite
- Signs of dehydration: not drinking, increased thirst, or changes in urination
- A kitten, a senior cat, or a cat with an existing health condition
- A swollen or painful belly, or you suspect they swallowed a toxin, plant, string, or object
- A fever, or any other symptom that worries you
Think your cat ate something toxic? Call ASPCA Animal Poison Control at (888) 426-4435, available 24/7.
Common Causes of Vomiting and Diarrhea in Cats
Most cases trace back to something ordinary:
- Hairballs — occasional hairball vomiting is normal; more than once a month is worth mentioning to your vet
- Dietary indiscretion — plants, table scraps, spoiled food, string, or foul-tasting things like certain insects
- Too many carbohydrates. Cats are carnivores that need a high-protein, low-carb diet, and some kibble is carb-heavy relative to protein
- A sudden food change
- Food allergies or intolerances
- Intestinal parasites
- Stress, especially after travel, boarding, or a change in routine
Less common but more serious causes include toxin ingestion (including poisonous plants, antifreeze, chocolate, or onions), a swallowed foreign object, inflammatory bowel disease, pancreatitis, and kidney, liver, or thyroid disease. These need a vet visit, not a home remedy — see the red-flag box above.
What to Do in the First 24 Hours
First, check for red flags. If your cat has any of the symptoms in the box above, call your vet before trying anything at home.
Ask your vet about a short rest for the gut. For a mild, one-off episode in an otherwise healthy adult cat, some vets recommend briefly withholding food to let the stomach settle. This isn't right for every cat — kittens, seniors, and cats with health conditions can be at risk from even a short fast, so check with your vet first.
Never withhold water. Keep fresh water available at all times to help prevent dehydration.
Reintroduce food with something bland. Once your cat is ready to eat again, a small portion of a plain protein — boiled chicken breast, egg, or whitefish, with no seasoning — is a gentle place to start.
Go slow getting back to normal food. If the bland diet stays down, gradually mix in your cat's regular food over several days rather than switching back all at once.
Watch closely. If vomiting or diarrhea continues past a day or two, comes back, or your cat seems worse at any point, call your vet.
When a Daily Probiotic Can Help
A probiotic is not a treatment for the causes above, and it will not fix a toxin ingestion, a blockage, or an infection that needs veterinary care. What it can do is support the balance of bacteria in your cat's gut — a balance that gets knocked around by diet changes, stress, and normal digestive upset, and that plays a real role in regular stool and day-to-day digestion. Once the acute episode has passed and your vet has ruled out anything serious, a daily probiotic is a simple way to support your cat's digestive health going forward.
How Probonix for Cats Works
Probonix is a liquid probiotic, not a pill or a powder, built around 8 of the most effective probiotic strains for general gut health and digestion:
- Bifidobacterium lactis
- Lactobacillus rhamnosus
- Enterococcus faecium
- Streptococcus thermophilus
- Lactobacillus acidophilus
- Lactobacillus casei
- Bifidobacterium bifidum
- Lactobacillus plantarum
The strains are carried in a proprietary acid-based formula designed to help more of the live culture survive the trip through your cat's stomach and reach the gut, rather than being broken down before it can do anything. Because it's a liquid, there's nothing to hide in food and nothing for a picky cat to sniff out and reject.
How to Use It
- Shake well before use. No refrigeration required.
- Suggested dose: 6 drops daily.
- Directions: Add the daily dose to your cat's food or water, once a day.
- Made with filtered water and natural flavor (non-GMO). Organic and non-GMO, and free of gluten, dairy, sugar, soy, eggs, fish/shellfish, and peanuts/tree nuts.
- For use in cats only. If your cat's condition worsens or doesn't improve, stop use and consult your veterinarian.
Probonix for Cats: Price & Guarantee
$37.97 per bottle (30-day supply, 0.5 oz). Subscribe & Save takes 25% off every order, or buy 2-3 bottles and save 12%, 4 or more and save 20%. Standard shipping is free on all US orders.
Backed by a 100% money-back guarantee: a full refund up to 30 days after purchase if you're not happy.
Cat Vomiting & Diarrhea FAQ
Why is my cat throwing up?
The most common cause is a hairball, which is normal from time to time. Other frequent causes include dietary indiscretion (plants, spoiled food, string), a diet that's too high in carbohydrates relative to protein, a sudden food change, or food intolerance. Vomiting more than once a week, or paired with lethargy, weight loss, or diarrhea, should be evaluated by a vet.
Why is my cat vomiting white foam?
White or foamy vomit is often just bile or gastric fluid brought up on an empty stomach, which can happen with hairballs or a mild stomach upset. If it happens repeatedly, or your cat seems unwell, have your vet take a look.
Why does my cat have diarrhea?
Common causes include dietary indiscretion, a new food, food intolerance, intestinal parasites, and stress from travel, boarding, or a change in routine. Diarrhea lasting more than a day or two, or paired with blood, vomiting, weakness, or weight loss, should be evaluated by a vet.
What can I give my cat for an upset stomach?
For a mild, one-off upset in an otherwise healthy adult cat, many vets suggest a short rest from food (check with your vet first, especially for kittens), constant access to fresh water, and then a bland, plain protein like boiled chicken breast, egg, or whitefish once your cat is ready to eat. A daily probiotic like Probonix can support normal digestion once the acute episode has passed.
Should I still give my cat water if they're vomiting?
Yes. Fresh water should always be available to help prevent dehydration, even when food is being withheld. If your cat can't keep water down or seems increasingly thirsty, that's a reason to call your vet.
When should I take my cat to the vet for vomiting or diarrhea?
Call your vet if you see blood, vomiting more than once a week, symptoms lasting more than a day or two, lethargy, weight loss, dehydration, a suspected toxin or foreign object, or if your cat is a kitten, senior, or has an existing health condition.
Can probiotics help a cat with diarrhea?
Probiotics support the balance of bacteria in the gut, which plays a role in regular digestion and stool consistency. They're a support tool for ongoing gut health, not a treatment for the underlying cause of diarrhea, so anything beyond a mild, short-lived episode should still be checked by a vet.
How do I give my cat Probonix?
Probonix is a liquid. Shake well, then add the suggested dose of 6 drops daily to your cat's food or water once a day. No refrigeration needed.
Is Probonix safe for kittens?
Probonix is formulated for cats, but every kitten is different. Talk to your veterinarian before starting any new supplement with a kitten.
How much does Probonix for Cats cost?
Probonix for Cats is $37.97 per 0.5 oz bottle (a 30-day supply) at humarian.com. Subscribe & Save takes 25% off every order, buying 2-3 bottles saves 12%, and 4 or more saves 20%. Standard shipping is free on all US orders, backed by a 100% money-back guarantee within 30 days.
Sources: VCA Animal Hospitals, Vomiting in Cats · VCA Animal Hospitals, Diarrhea in Cats · Cornell Feline Health Center, Vomiting · ASPCA Animal Poison Control Center