Cat Throwing Up White Foam? Here’s What It Means

Your cat throws up white foam. Then does it again. Most people assume it is a hairball and move on. But that foam can also be the first sign of a swallowed string, a poisonous flower, or a liver problem that can start after only a day without food.

This guide is general information, not a diagnosis. When in doubt, call your vet.

What white foam actually is

White foam is mostly stomach fluid, mucus and air. When the stomach is empty, that fluid is all that comes up. So the foam tells you the stomach was empty. It does not tell you why your cat is vomiting.

Three causes you can usually manage at home

1. An empty stomach

Some cats vomit foam when too many hours pass between meals, often early in the morning. Split the same daily food into three or four smaller meals, or add a small bedtime snack.

2. Hairballs

One or two a month is generally considered normal. More than that is worth a vet visit. But if your cat keeps retching and nothing comes out, that can mean a blockage. Call your vet the same day.

3. Eating too fast

A slow feeder bowl, a puzzle feeder or spreading food on a flat plate forces smaller bites.

Three causes where waiting is risky

4. A swallowed string

String, ribbon, thread or a hair tie can get stuck at one end, often around the base of the tongue, while the rest moves into the intestines. The gut bunches up along it like an accordion, and the string can cut into the intestinal wall.

The rule: if you see string hanging from your cat’s mouth or rear end, do not pull it. Pulling can slice through the intestines. Go straight to the vet.

5. Poisoning, especially lilies

Easter, tiger, Asiatic and stargazer lilies, plus daylilies, can cause kidney failure. Chewing a leaf, licking pollen off fur or drinking vase water can be enough. According to the ASPCA, an untreated cat can develop kidney failure within about 36 to 72 hours.

If your cat got near a lily, do not wait for symptoms. Take the cat and the plant to a vet, or call ASPCA Animal Poison Control at 888-426-4435.

6. An ongoing illness

Inflammatory bowel disease, intestinal cancer, kidney disease, an overactive thyroid or diabetes can all cause repeated vomiting. Researchers at the Alamo Feline Health Center in Texas found that cats vomiting more than twice in four weeks had a high chance of long-term intestinal disease. For cats over 10, vomiting plus weight loss is a warning sign, even if the cat acts normal.

Why a cat that stops eating is an emergency

When a cat stops eating, fat floods the liver faster than it can handle, causing fatty liver disease, which can be fatal. Cornell’s Feline Health Center warns that appetite loss for as little as 24 hours can seriously affect an adult cat. For kittens, call after about 12 hours.