Vomiting in Cats—When Should You See a Veterinarian?

Dr. Leslie Wohlgroth, DVM, answers the most important questions about vomiting.

This interview explains what to look out for, when to take your pet to the vet, and why it’s not normal to “vomit every now and then.”

Vomiting in cats is often downplayed—why is this problematic from a veterinary perspective?

Vomiting is often considered “normal” in cats, especially when associated with hairballs. From a veterinary perspective, however, this is problematic, as vomiting is always a symptom and not a diagnosis in itself. Even seemingly mild or infrequent vomiting can be a sign of an underlying condition—such as in the gastrointestinal tract or other organ systems. If this is ignored over an extended period, the underlying condition may worsen unnoticed.

What is the main difference between regurgitation and vomiting—and how can pet owners tell the difference?

Vomiting is an active process that is accompanied by nausea, abdominal contractions, and often warning signs such as restlessness or excessive salivation. The food is usually partially digested.

Regurgitation, on the other hand, is a passive process: food is brought back up without warning and without any active abdominal movements, often shortly after eating and usually undigested. Close observation by the owner is crucial for distinguishing between the two.

Is regurgitation common in cats?

Compared to vomiting, regurgitation is much less common in cats. When it does occur, the examination should focus specifically on causes related to the esophagus, such as motility disorders or structural abnormalities.

How often is it normal for a cat to cough up hairballs—and when does it become a cause for concern?

Occasional hairball expulsion can occur in cats that groom themselves extensively. As a general rule of thumb, for long-haired cats, one hairball per month is still considered normal.

On the other hand, frequent hairballs or vomiting of hairballs in short-haired cats is always a sign of an underlying problem. This is often caused by excessive grooming—for example, due to itching, skin conditions, or stress.

If the hairball is vomited up, the problem is “solved” in the short term, but it can become more serious if a hairball gets stuck in the small intestine and causes an intestinal obstruction there.

Do all cats vomit hairballs, or is that just a common myth?

Not every cat vomits hairballs. Short-haired cats should vomit hairballs only very rarely. Many cats pass ingested hair unnoticed in their feces.

Frequent vomiting of hairballs is therefore not a normal physiological condition, but may indicate skin problems involving excessive grooming due to itching, gastrointestinal motility disorders, or other medical conditions.

Why do cats eat grass—and does it actually make them vomit on purpose?

Eating grass is a natural behavior whose exact function has not yet been conclusively determined by science. Among other things, it is thought to aid digestion or provide a source of dietary fiber.

Grass can trigger vomiting and further irritate the stomach, though this isn’t always the case and doesn’t happen to every cat. If a cat eats a lot of grass and regularly vomits it up, you should try to stop it from eating grass. Otherwise, a vicious cycle can develop: The stomach becomes irritated, the cat eats grass, which further irritates the stomach, causing it to vomit again, and then the cat eats grass once more.

In addition, grass can enter the nasal passages when a dog vomits and get stuck there as a foreign object. In some cases, it must be removed under anesthesia.

At what point should pet owners start paying attention—are there clear warning signs or a “threshold” that indicates the need for further evaluation?

If a cat vomits more than once or twice a month, you should have it examined by a veterinarian.

Interestingly, a study conducted at the Zurich University Veterinary Hospital, which examined cats belonging to staff members and students, found that animals that vomited at least once a month were significantly more likely to have chronic inflammation and lymphomas in the gastrointestinal tract.

Other warning signs include weight loss, changes in appetite, lethargy, diarrhea, or blood in the vomit. Any sudden deterioration in the cat’s overall condition also requires prompt evaluation. If a cat also appears lethargic and is not eating well, you should not wait 24 hours but should see a veterinarian as soon as possible.

How do you assess chronic, seemingly mild vomiting that persists over a long period of time?

Chronic vomiting, even if it seems mild, should always be taken seriously. In cats, in particular, chronic conditions can show only very subtle symptoms over a long period of time. It’s important to remember that cats are masters at hiding their discomfort.

"Occasional" vomiting over a period of months or years should therefore not be considered normal, but should be investigated by a doctor.

What are the most common causes of vomiting in cats?

The most common causes include food intolerances, inflammatory diseases of the gastrointestinal tract, lymphoma, parasitic infestations, and hairball problems.

In addition, systemic conditions such as kidney failure, liver inflammation, thyroid disorders, or pancreatitis may also be a factor.

What role do chronic conditions such as IBD, pancreatitis, or kidney disease play?

Chronic conditions play a very important role. Inflammatory bowel disease (IBD), as well as intestinal lymphomas, pancreatitis, and kidney disease, are among the common causes of recurrent vomiting.

These conditions often develop gradually and are therefore not diagnosed until late in the course of the disease, after symptoms have been overlooked for an extended period of time.

How often are food intolerances or feeding errors the cause?

Food intolerances are not an uncommon cause and should be considered early on, especially in cases of chronic vomiting—along with a possible worm infestation.

Feeding mistakes, such as eating too quickly or an unsuitable diet, can also play a role. Some cats have trouble digesting high-protein food, while others are sensitive to high fat content or large amounts of fiber.

If cats vomit immediately after eating too quickly, slow feeders, interactive feeding toys, and several small meals may be helpful—an approach that is generally recommended for many cats.

What diagnostic steps do you take when a cat is vomiting repeatedly?

The diagnostic process is carried out in stages. Following a thorough medical history—including questions about deworming—and a clinical examination, further tests are ordered based on the findings. These may include blood tests, fecal examinations, imaging procedures such as ultrasound or X-rays, and, if necessary, endoscopic or histological examinations.

Blood tests usually require a comprehensive evaluation of all relevant organ systems, as a diagnosis that is too narrowly focused can easily overlook the actual cause.

What information from owners is particularly important for the diagnosis?

It is very important to provide information on the frequency and timing of the vomiting, the appearance of the vomit, feeding habits, and any accompanying symptoms.

Changes in behavior, weight, or appetite can also provide key clues. In practice, videos can be very helpful in distinguishing between vomiting and regurgitation.

How is treatment tailored to the cause—and what role does diet play in this?

Treatment is always tailored to the underlying cause. It can range from dietary measures and medication to specific therapies for underlying conditions. Diet often plays a key role, particularly in cases of food intolerance or chronic intestinal diseases.

When it comes to food allergies, it is important to know that cats often exhibit what are known as delayed reactions. This means that symptoms can appear up to two weeks after exposure to an incompatible food and may persist for weeks afterward. This makes it nearly impossible to identify the triggering food based on observation alone.

In addition, cats often react to very common ingredients such as fish, chicken, beef, or rice—precisely the ingredients that are often found in trace amounts in commercially available “hypoallergenic” pet foods.

If an elimination diet is being followed, it must therefore be strictly adhered to—ideally for at least two months, without any snacks or unauthorized supplements. Such diets should be planned in close consultation with a veterinarian whenever possible.

What is your most important piece of advice for owners whose cats vomit "from time to time"?

Vomiting should never be considered normal in cats. Even if it occurs only occasionally, it’s worth getting it checked out as soon as possible. The sooner the cause is identified, the better the treatment options and prognosis are generally likely to be.