My cat is vomiting: when is it serious?

Vomiting is the forceful bringing up of stomach contents. The cat usually shows nausea first: drooling, licking its lips, swallowing a lot, restlessness. Then the belly muscles heave and food, fluid or foam comes up.

Vomiting is a sign, not a disease. It can be a harmless clean-out of the stomach, or the first sign of a gut problem or of illness elsewhere in the body, such as the kidneys, liver, pancreas or thyroid.

Almost all cats vomit now and then. In one study, 35% of 100 healthy cats had vomited at least once in the previous 30 days. How often, what it looks like and what else is going on matter more than the single vomit.

Vets call vomiting that has lasted less than a week acute and vomiting that has lasted more than about three weeks chronic. Acute vomiting often starts suddenly and settles in a day or two. Chronic vomiting is not likely to go away without finding the cause.

Regurgitation is passive. Food comes back soon after eating, with no nausea and no heaving, often still looking like it did going in, sometimes in a tube shape covered in mucus. It can happen in healthy cats that eat too fast, but repeated regurgitation needs a vet's advice.

A hairball is a damp tube of matted fur, usually brought up with a little foam or fluid after gagging or hacking. Loose strands in ordinary vomit do not make it a hairball, because most cats swallow some fur.

A cat that coughs usually crouches low with the neck stretched out, and may bring up a little white foam. That can look like vomiting or a hairball, but it comes from the airways. Repeated coughing needs a vet. A cat that retches and breathes fast may have a problem in the airways or heart rather than the stomach.

Vomiting, regurgitation, retching and coughing are easy to confuse. That is one reason the vet wants a clear description, and ideally a short phone video, of what happens.

Clear liquid or white foam usually means the stomach was empty and a little acid or mucus came up. Once in a while it is mild. Repeated foam, or clear fluid in an older cat, deserves a check, because it can go with kidney disease or gut inflammation.

Yellow or green fluid is mostly bile. It often comes up in the early morning after a long gap without food. One episode is usually minor. Bile vomit that returns again and again, or every day, needs a vet, because it can go with liver, pancreas or gut disease.

Undigested food soon after a meal usually points to eating too fast, or to regurgitation. Undigested food hours after a meal can mean the stomach is not emptying properly, and a vet should look at it. Fur in a tube is a hairball. Hair in the vomit, often, can point to over-grooming from stress, skin disease, fleas or gut disease.

Green vomit with bits of plant usually means the cat ate plants or grass. Spaghetti-like strands can be roundworms, and need vet treatment.

Red or pink vomit, black vomit, or vomit that looks like coffee grounds can mean bleeding in the mouth, throat, stomach or upper gut. Treat it as an emergency. Brown, foul-smelling vomit can be digested blood or contents from lower in the gut, and vomit that smells like faeces can point to a blocked bowel. Both need a vet promptly.

Hairballs. Cats swallow fur while grooming, and it can irritate the stomach. An occasional hairball is common, especially in long-haired cats and in the shedding season. Frequent hairball vomiting is not normal, and can point to over-grooming, skin disease or gut problems.

Eating too fast or too much. A cat that gulps food and air may bring it back minutes later and then act normal. Small meals, a slow-feeder bowl and less competition at the bowl help, and a vet should hear about it if it keeps happening.

A sudden change of food, treats, table scraps or something eaten outside is a common cause of one-off vomiting and diarrhoea. Changing food gradually over about 7 to 10 days is the usual advice. Food intolerance or allergy can cause repeated vomiting, sometimes with diarrhoea or itching. After parasites are ruled out, food problems are one of the most common causes of ongoing digestive signs in cats. A vet may suggest a diet trial.

Worms and other gut parasites often cause vomiting, especially in kittens and cats that hunt or go outside. Worms in the vomit or stool are a reason to see a vet. Grass: many cats nibble grass, and some vomit afterwards. Sources disagree on why: one charity says it seems to help digestion, another lists it as a sign a cat may feel sick, and indoor cats may do it to bring up hair. Ask the vet if the habit is a worry.

Other causes include motion sickness, medicines and supplements, stress and anxiety (only after medical causes are ruled out), a stomach infection, and mild stomach inflammation (gastritis).

Vomiting can be the first sign of poisoning, before tremors, collapse or organ failure. Common hazards are lilies, other toxic plants, human medicines such as paracetamol, household cleaners, antifreeze, essential oils, chocolate, onions and some flea products.

Real lilies (Lilium, such as Easter, tiger, stargazer and Asiatic lilies) and daylilies are very dangerous for cats. All parts are toxic, and a single leaf or petal, drinking vase water or grooming pollen off the fur can be enough to cause kidney failure.

Lily poisoning often starts with vomiting, no appetite and dullness within a few hours. The vomiting can stop and return a day or two later, as the kidneys fail. Kidney failure is often fatal if treatment is delayed longer than about 18 hours. Other plants named as harmful include lily of the valley (heart problems), peace lily (mouth pain, drooling, vomiting, rarely life-threatening), dieffenbachia and philodendron.

A cat that may have eaten a lily or any toxin needs a vet or a poison service straight away, even if it looks fine. Do not wait for symptoms, and do not try to make the cat vomit.

Cats can swallow string, thread, wool, ribbon, tinsel, hair ties (elastics), rubber bands, plastic, toys, paperclips or bones. The most common foreign body in cats is a linear one such as sewing thread.

A string can stay anchored under the tongue or in the stomach while the rest is pulled along the gut. The gut bunches up around it and can be cut or torn, so a linear foreign body is an emergency even when the cat has vomited only once or twice.

Signs of a blockage can include repeated vomiting, retching with nothing coming up, hiding, no appetite, a hunched posture, a painful or swollen belly and, later, vomit that smells like faeces.

Vets usually need an X-ray or ultrasound, may look in the mouth under anaesthesia, and often operate to remove a swallowed string or a blockage. A hairball too large to bring up can also block the gut. A court decision in a kitten that kept vomiting records a blocked small intestine found only at surgery. It is one case, but it shows why a vet may offer an X-ray when a blockage cannot be ruled out by examination alone.

In cats over about 10, vomiting is usually a sign of an underlying illness, not normal ageing. Many causes are treatable or manageable once found.

Chronic kidney disease. Waste products the kidneys no longer clear irritate the stomach. Other signs are more thirst and urine, poor appetite and weight loss. It is managed rather than cured, with diet, fluids and medicine against nausea. Hyperthyroidism, an overactive thyroid, is the most common hormone disease of older cats. Weight loss despite a good appetite is the main sign, with restlessness, thirst and sometimes vomiting. It is diagnosed with a blood test and treated with medicine, diet, surgery or radioactive iodine.

Inflammatory bowel disease (IBD) and low-grade gut lymphoma are the two most common causes of chronic vomiting when no cause outside the gut is found. They look alike, and a tissue biopsy is usually needed to tell them apart. Early diagnosis matters because IBD can progress to lymphoma. Pancreatitis in cats is often low-grade, with on-and-off vomiting, poor appetite, tiredness and weight loss, and few signs of belly pain. Diabetes can cause vomiting, particularly when it becomes ketoacidosis, together with thirst, more urine and weight loss. Liver disease can add yellow gums or eyes.

Cats rarely show belly pain, and a normal-looking cat can still be ill. Cats hide illness, so vomiting may be the only early sign an owner sees. Many cats with chronic vomiting look well between episodes, and owners often put it down to hairballs, a sensitive stomach or eating too fast. Vets say these excuses can hide chronic gut disease for months or years.

Kittens dehydrate after only a few vomiting episodes, and very young or very old cats are more likely to be seriously affected. A kitten with repeated vomiting should see a vet the same day.

Worms are a common cause in kittens that have not been wormed, and kittens can vomit worms. Unvaccinated kittens are also at risk from infections. Kittens are curious, and swallowed objects such as string or small toys are a danger at this age. Kittens should not skip meals, and a kitten that vomits more than once or twice should be seen by a vet. Some vomiting medicines are not suitable for very young kittens, so a vet should always choose the medicine.

Vomiting with diarrhoea can cause dehydration quickly, especially in kittens, older cats and cats that are not drinking. Causes include food upset, parasites, infections, poisons, food intolerance and chronic gut disease.

Sources differ on urgency. Most call it a reason for a prompt vet visit, and an emergency if the cat is weak, dull, dehydrated or cannot keep water down. Diarrhoea has its own page, with causes and what to ask the vet.

Sources do not agree on one number. Some vets say more than once or twice a month is a reason to see a vet, others say more than once a week, and one study of surgery cases frames vomiting more than twice a month as abnormal. All agree that vomiting that is increasing, regular or paired with other signs should be checked.

Three or more vomiting episodes within 24 hours, or several in a few hours, is generally considered concerning by emergency vets. This is a rule of thumb rather than a guideline. Daily vomiting, even in a cat that seems well in between, needs a vet. Chronic vomiting is not a normal part of being a cat.

A single vomit in a bright cat that is eating, drinking and acting normally is usually less worrying, and many sources say it can be watched for about a day. If you are unsure, call the practice for advice. Cats that vomit once every few weeks are still worth mentioning to the vet at the next visit.

Dehydration. Repeated vomiting loses fluid and body salts. Kittens, older cats and cats with chronic illness are hit hardest.

Fatty liver (hepatic lipidosis). A cat that stops eating for more than about 24 hours, especially an overweight cat, can develop a dangerous liver problem. Vets watch food intake closely in a vomiting cat. A cat that vomits can also breathe vomit into the lungs and develop aspiration pneumonia.

A blocked or torn gut, poisoning and kidney failure from lilies are the quick dangers. They are why the emergency list on this page exists.

The vet starts with questions and a physical exam: the belly, the mouth, hydration and weight, and in older cats the neck for an enlarged thyroid. For a short bout in a stable cat, supportive care may be enough. Treatment for a mild bout can include anti-nausea medicine, fluids under the skin or a drip in hospital, stomach protection and a gentle, easily digestible diet. The vet picks the medicine and the amount; this page does not.

Tests depend on the cat. Common ones are blood and urine tests, a thyroid test in middle-aged and older cats, a faecal test for parasites, X-rays and ultrasound. Ultrasound is the usual imaging test for vomiting in cats. For long-term vomiting, a vet may try a diet trial with a hydrolysed or novel-protein food. Many cats respond within 2 to 3 weeks, sometimes 6 to 8, and other tests follow if there is no change.

IBD and gut lymphoma can only be told apart with a biopsy, taken by endoscopy or at surgery. Treatment is diet, and sometimes medicines that calm the immune system or chemotherapy. When IBD is found early, many cats are managed well for years. A swallowed string or blockage usually needs urgent surgery. Lily poisoning needs hospital treatment for the kidneys, started early.

A cat that is not eating may need appetite support or a feeding tube once the vomiting is under control. Sources differ on withholding food. Some vets rest the gut for a short time and some warn against long gaps in a cat. Do not fast a cat or a kitten, or force-feed it, unless the vet tells you to.

Brush regularly, daily for long-haired cats, to take loose fur away. Ask the vet if a hairball diet or supplement suits your cat. For cats that gulp, use smaller and more frequent meals, a slow-feeder or puzzle bowl, and separate bowls in multi-cat homes.

Change food slowly over 7 to 10 days, and keep a new food for a sensitive cat for the vet to choose. Keep string, wool, ribbon, hair ties, rubber bands, small toys, medicines, cleaners and lilies out of reach. If you want flowers, choose ones that are not toxic.

Keep worming and flea control up to date, as the vet advises. Cats that go outside are often checked about every three to four months. Regular check-ups and blood tests in older cats can find kidney disease, hyperthyroidism and diabetes early.