Why Is My Cat Vomiting? 6 Causes and When to Call the Vet
Every cat vomits sometimes, and a single episode after eating too fast or coughing up a hairball is usually nothing to worry about. But vomiting that keeps happening — more than once a week, or several times in a day — is your cat telling you something is wrong, and it is worth working out which of the common causes fits. The key distinction vets ask about first: is it vomiting (active heaving, abdominal effort, partially digested food) or regurgitation (passive, undigested food, no heaving, usually right after eating)? Note what came up, when it happened relative to meals, and whether your cat is otherwise eating, drinking, and behaving normally. Those details help your vet enormously.
Start with the simplest checks. Has anything changed — a new food, a new treat, a plant nibbled, a medication started? Is your cat drinking and using the litter box normally? A cat that vomits but is bright, hungry, and active is a very different case from a cat that vomits and hides, refuses food, or stops drinking. When in doubt, call your vet and describe the pattern: frequency, timing, and what the vomit looks like. That phone call costs nothing and can catch the serious causes early.
1. Eating too fast, or too much at once
The most common cause of occasional vomiting in otherwise healthy cats is simply eating too quickly, especially dry food that then swells in the stomach. The fix is easy: feed smaller meals more often, use a slow-feeder bowl or scatter food on a flat plate, and keep mealtimes calm — cats that compete with other pets for food bolt it down. If the vomiting stops with slower feeding, you have your answer. If it continues despite small, slow meals, move down this list.
2. Hairballs
Cats groom constantly and swallow fur, which usually passes through harmlessly. Long-haired cats and heavy groomers sometimes build up hairballs that come back up as a sausage-shaped clump, often with a little fluid. Regular brushing is the real fix — it removes the fur before your cat swallows it — and a hairball-control diet or paste can help for frequent cases. Vomiting hairballs more than once or twice a month, or retching without producing anything, deserves a vet check, because it can also signal stomach inflammation. Our cat grooming guide covers the brushing routine that prevents most hairballs.
3. Food intolerance or a sudden diet change
A new food, a new treat, or table scraps (especially milk — most adult cats are lactose intolerant) can trigger vomiting within hours. Switch foods gradually over seven to ten days, mixing increasing amounts of the new food with the old. If vomiting started with a specific new item, stop it and see if the vomiting stops too. True food allergies are less common than intolerances, but a vet-supervised elimination diet is the way to identify them — do not guess with endless food changes, which only upset the stomach further.
4. Plants, strings, and things cats should not eat
Lilies are the emergency here: even a small nibble of a lily leaf or pollen can cause fatal kidney failure in cats, and any lily exposure is an immediate vet emergency, not a wait-and-see. Other culprits include string, ribbon, and hair ties, which can tangle in the gut, and toxic houseplants. If you suspect your cat ate something dangerous, call your vet or an emergency clinic straight away and say exactly what it was and when — do not try to make your cat vomit at home unless a vet tells you to.
5. Parasites and stomach infections
Worms, especially in kittens and outdoor cats, can cause vomiting along with a dull coat, a swollen belly, or worms visible in vomit or stool. A vet can test a stool sample and prescribe the right wormer — over-the-counter products do not cover every parasite. Stomach infections and inflammation (gastritis) also cause repeated vomiting, sometimes with diarrhoea or loss of appetite. These need veterinary diagnosis, because the treatment depends entirely on the cause.
6. Serious causes: blockages, kidney disease, and more
Repeated vomiting with loss of appetite, lethargy, weight loss, or a painful, swollen belly can point to an intestinal blockage, kidney disease, liver disease, pancreatitis, or hyperthyroidism (common in older cats). A blockage is an emergency: vomiting, straining, no stool, and a painful abdomen mean same-day vet care. Older cats that vomit regularly plus drink more and lose weight should be checked for kidney and thyroid problems with a simple blood test. Early detection changes outcomes for all of these, so do not wait weeks to see if it passes.
When to call the vet — the quick checklist
Call the vet the same day if your cat vomits more than twice in 24 hours, has blood in the vomit, cannot keep water down, has not eaten for 24 hours, is lethargic or hiding, has diarrhoea as well, or may have eaten lilies, string, or medication. Call urgently — do not wait — for a suspected blockage, a swollen or painful belly, or collapse. Otherwise, if your cat vomits once, then eats, drinks, and plays normally, monitor it: note the pattern for a week, fix the feeding and grooming basics, and book a routine check if it happens again. If your cat has also stopped using the litter box, our litter-box guide helps separate a behaviour problem from a medical one.
Most cat vomiting is fixable — slower feeding, regular brushing, a gradual diet change, and removing the dangerous plants and strings from your home solve the majority of cases. What matters is the pattern: occasional and otherwise well is usually fine; frequent, worsening, or paired with other symptoms is a vet visit. Your cat cannot tell you what hurts — the vomit pattern is one of the few clues it can give you, so pay attention to it.
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