My cat is vomiting: causes, home care & when to call the vet
A plain-English guide to vomiting in cats — what\'s usually fine, what isn\'t, and what to do today.
Vomiting in cats is so common that owners often dismiss it as normal — but veterinary medicine has shifted hard on this in the last decade. A cat who vomits more than once a month is not "just throwing up a hairball"; chronic vomiting is now treated as the early sign of inflammatory bowel disease, food allergy, or even small-cell lymphoma until proven otherwise.
That said, not every vomit is a crisis. A single vomit in an otherwise bright cat who returns to eating and using the litter tray is usually a one-off. Pattern is the signal — frequency, what comes up, paired symptoms (weight loss, appetite change, water intake), and how the cat looks between episodes.
Cats hide illness expertly. By the time vomiting is "obvious," the underlying condition may have been present for months. The Pet Capsule weight + intake log was built around exactly this — small drifts that matter.
Common causes
Hairballs (trichobezoars)
Monitor at homeLong-haired cats produce occasional hairball vomits; more than once a month is excessive and worth addressing.
Eating too fast
Monitor at homeCat empties a bowl and then vomits whole kibble minutes later. Solved with slow feeders or smaller frequent meals.
Food intolerance or allergy
See a vet within 24–48 hoursSpecific protein or carbohydrate triggers chronic vomiting and/or diarrhoea. Diagnosed by elimination diet.
Read more about food intolerance or allergy →Chronic inflammatory bowel disease
See a vet within 24–48 hoursCommon in middle-aged and senior cats. Chronic vomiting, weight loss, sometimes diarrhoea. Requires biopsy to differentiate from lymphoma.
Read more about chronic inflammatory bowel disease →Hyperthyroidism
See a vet within 24–48 hoursSenior cats. Vomiting, weight loss despite huge appetite, increased thirst, hyperactivity. Treatable.
Read more about hyperthyroidism →Chronic kidney disease
See a vet within 24–48 hoursSenior cats. Vomiting, weight loss, increased thirst and urination. Manageable when caught early.
Read more about chronic kidney disease →Foreign body — especially string
Emergency — vet nowCats love thread, ribbon, tinsel, hair ties. A linear foreign body anchored at one end is a surgical emergency.
Toxin ingestion
Emergency — vet nowLilies (all parts, even pollen — kidney failure within 36 hours), paracetamol (single tablet can be fatal), antifreeze, certain essential oils.
Pancreatitis
See a vet within 24–48 hoursCats present subtly — vomiting, lethargy, appetite loss, sometimes jaundice. Specific blood test needed.
Read more about pancreatitis →What you can safely do at home
- For a single vomit in a bright cat: withhold food for 4 hours (never longer in cats — they can develop hepatic lipidosis), then offer small bland meal.
- Keep fresh water available; offer extra wet food to support hydration.
- Use a slow feeder or split meals into 4–6 small portions if vomiting follows eating quickly.
- Keep all string, ribbon, hair elastics, tinsel, and dental floss completely out of reach.
- Track vomit frequency in a log — once a month is the threshold above which most vets will investigate.
- Never withhold food from a cat for more than 24 hours — even overweight cats can develop fatal hepatic lipidosis from short fasts.
These steps are general guidance for an otherwise well, healthy adult pet. If your cat is a puppy/kitten, a senior, or has a known chronic condition, call a vet rather than waiting it out.
What to expect at the vet
The vet will usually:
- Full physical, including abdominal palpation and thyroid check (gland palpation)
- Bloodwork including CBC, biochemistry, T4 thyroid, and feline pancreas-specific lipase
- Urinalysis to assess kidney concentrating ability
- Abdominal ultrasound if chronic vomiting — this is the highest-yield single test
- Anti-nausea medication and supportive fluids while investigating
Useful questions to ask:
- Could this be hyperthyroid, kidney, IBD, or lymphoma?
- Should we ultrasound the abdomen today?
- Is a hydrolysed-protein diet trial appropriate?
- When does chronic vomiting warrant biopsy?
How to reduce the chance of it happening again
- Regular grooming for long-haired cats reduces hairballs.
- Slow feeders for fast eaters.
- Slow food transitions over 7+ days.
- No lilies in the home, ever — every part is fatal.
- Annual senior bloodwork + thyroid from age 7; twice yearly from age 12.
- Keep string, ribbon, and tinsel out of reach permanently.
Frequently asked questions
Is my cat just throwing up a hairball — or is it more?
Once a month or less, in a long-haired cat who is otherwise thriving, is usually hairballs. More than once a month, any frequency in a short-haired cat, or alongside weight loss or appetite change, warrants vet investigation.
My cat vomits right after eating — is it serious?
Usually fast eating. Try a slow feeder or smaller frequent meals. If it persists, or the cat loses weight, see a vet — chronic vomiting in cats is meaningfully more serious than it has historically been treated.
How dangerous are lilies?
Catastrophically. Every part of true lilies (Lilium and Hemerocallis genera) — leaves, petals, pollen, water from the vase — causes acute kidney failure within 24–72 hours. No lilies in any home with cats, ever.
Can I give my cat anti-nausea medicine from the pharmacy?
No. Cats lack the liver enzyme to safely metabolise paracetamol and many other human drugs — a single tablet can be fatal. Only use medications prescribed by a vet for your specific cat.
My cat is vomiting and not eating — how long can I wait?
Not long. Cats who don't eat for 2–3 days, especially overweight cats, can develop hepatic lipidosis — a serious liver condition. Any cat refusing food for more than 24 hours needs a vet visit.