Why Is Your Cat Throwing Up Clear Liquid?

Cats vomit all the time and it always seems like they like to do it in hard-to-clean places like the carpet instead of on a tiled floor. Some of them do it once a month, some once a week, and some do it in the summer months only. You often can’t even tell the reason they throw up or what comes out; it’s just a part of life.

However, as responsible cat parents, it is important that we note when this behavior occurs, what happened before the cat exhibited this behavior, and how often it occurs. This is important because vomiting, while seemingly harmless and regular, may be a symptom of a life-threatening disease.

What Is That?

Before we look into cats vomiting clear liquid, let’s delve into other “variants”. If you have a sensitive disposition, then we suggest you skip this section.

Yellow vomit, discounting that your cat ate the food of that color, contains bile. This is usually released into the upper small intestine. It suggests that the problem may not just be located in the stomach, but also in the small intestine.

Vomit with bright red blood usually means there is fresh blood in the vomit. This may be because of a stomach ulcer. Blood that is more reddish-brown can mean the problem may be in the upper small intestine instead.

Excess amounts of mucus in the vomit can be caused by an inflamed intestine. It also may be confused with retching or coughing up mucus, which can look similar to vomiting mucus.

A lot of times, vomiting will contain undigested food. This is more accurately termed “regurgitation” and typically happens very soon after the cat eats a meal. The food has not traveled beyond the tummy and hasn’t had time to be digested. This is not indicative of any particular disease and could be something as benign as overeating, eating quickly, very cold, or hot food. Sometimes, though, it could be something much more serious, like a digestive blockage or anatomical problem with the swallowing mechanism.

Strong fecal odors accompanying the vomit may mean the presence of intestinal obstructions. This is extremely dangerous and should be considered an emergency.

Before we turn into connoisseurs of vomit, let’s get back on topic. After reading about different forms and colors and their implications above, you might think that your cat may not have a very serious problem if it’s vomiting clear liquid compared to a cat throwing up something red and bubbly. However, clear vomit can also be a symptom of most of the problems above.

Is The Cat Vomiting Water?

When a cat vomits clear liquid, it is normal for the owner to assume that it is just water. Since clear vomit comes from the digestive tract it may just be water along with some gastric juice. But what’s important is why the cat is doing this.

Natural Reasons For Omitting

Swallowing Hairballs

Hairballs are formed when the cat grooms itself and fur gets stuck in the tongue and gets swallowed.

These hairballs cannot be digested and accumulate in the stomach. Most of the hair passes harmlessly through the digestive tract and is eliminated in the litter box. Some collect, though, at the juncture of the esophagus and stomach, and moves no further. Vomiting is the cat’s way to eject this accumulation.

This happens in two stages: the cat first vomits a clear liquid, then the hairball. Other symptoms include reduced appetite and constipation.

In the worst case, surgery may be necessary, but the impact of shedding can be reduced by giving the cat a balanced diet that promotes healthy skin and fur. Regularly brushing their coat also helps.

Especially in households that have three or more cats, there is always one cat that likes to groom everyone else. This cat may be more prone to hairballs than the others. One way to avoid this is to groom them using tools made for that purpose.

Swallowing Strings/Yarn

Related to hairballs are strings or yarn. Cats don’t usually swallow plastic toys but it’s possible for them to swallow string or yarn fibers which get stuck in their teeth when they bite and play around. These will accumulate and cause the same symptoms as hairballs.

This can be dangerous, as the end of the string can get lodged around the base of the tongue when it is swallowed. If the string passes into the intestine, it can also cause bunching or cutting of the intestinal wall.

Surgery may be necessary in some cases but this can be prevented by keeping a close eye on what the cat is playing with and giving them proper toys.


Poisoning should also be considered, especially some of the fatal cat poisons found around your home. Even though cats do not lick poison off the floor or other places, they will lick themselves to the groom.

When playing in the cabinet, the detergent powder may spill on your cat’s coat or the cat may step on liquid pesticide and lick its paws to clean it.

Some cats also like to chew on plants, or more commonly, bat and claw them, especially if they are young and curious. Lilies in particular are extremely poisonous to your cat. Drinking the water from the lily vase can kill your cat.

Poisoning may cause other symptoms like increased thirst, diarrhea, confusion, lethargy, and seizures. The best way to prevent this is to “cat proof” the house. Make sure that the furry explorer can’t enter cabinets or drawers and can’t play with the hazardous material.

Food Related

Gastrointestinal problems such as constipation, food allergies, and inflammatory bowel disease may also cause the cat to vomit clear liquid. In addition, a more benign reason may be simply switching your cat’s food too quickly. When making changes to food, it should be done gradually over the course of a week, unless medical reasons dictate a quicker change.

Portion-fed cats will begin to anticipate food around their feeding time and if they don’t get it and only drink water, gastric juices can irritate their stomach and they’ll vomit clear liquid.

Also related to skipping meals are gobbling food quickly and overeating. This can be a stress response due to the presence of other cats. The cat is eating too fast to get away as soon as possible, so its food doesn’t get eaten by another cat, or so it can finish first and then visit its neighbor for more.

Other Organ Failures and Diseases Like Thyroidism, Cancer

Since the problem involves vomiting, one would think that this is a problem exclusive to the gastrointestinal system—the stomach, intestines, mouth, and esophagus.

However, don’t rule out problems with other organs in the body such as the liver and kidney. These vital organs play a role in the excretion of toxins and the regulation of electrolytes. If these become affected then it can cause the cat to become exceedingly nauseous. There are also other causes that may be indirectly causing the vomiting.

Hyperthyroidism is a disease that causes an overactive thyroid and increased thyroid hormones. The thyroid is an organ that influences the metabolism of the body. Symptoms include oily skin, greasy hair, excessive salivation, increased hunger, increased heart rate, and vomiting. The vomiting is likely to be linked to the increased speed of eating. Hyperthyroidism may be treated by thyroid medication or via surgery to remove the thyroid gland. In some parts of the world, destroying the thyroid with radioactive iodine is also a treatment option, however, it requires intensive management during treatment and strict quarantine and so will not be offered by your general veterinarian.

Internal parasites such as roundworms and tapeworms may cause vomiting. These can cause impactions and inflammation in the guts. It is therefore very important to give your cat antiparasitic medication every 3-6 months, especially if he is a scavenger, to prevent these common infections.

Lastly, tumors and other types of cancer in cats may manifest itself as poor appetite, weight loss, diarrhea, and vomit that can include blood. The symptoms in themselves can be hard to diagnose but cancer can easily be detected via internal imaging such as X-rays and abdominal ultrasound scans. Once diagnosed, surgery or chemotherapy may be needed to treat cancer, however, some cancers can only be pushed into remission rather than fully cured.

unwell cat sleeping

What Do I Do?

Vomiting can be harmless in some cases, for example after the cat eats very quickly. That said, it’s better to consult a vet to address a problem early on rather than later because vomiting may cause dehydration and weakness. It is especially important to take your cat to the vet when it is showing signs of distress and other symptoms such as weight loss, diarrhea, excessive thirst, lethargy, pacing, nausea, no stools, or excessive drooling.

Dr. Jo Hardy(Jo de Klerk) is a veterinarian from the United Kingdom and is an avid writer/speaker alongside her clinical work.

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