Cat Throwing Up Green Bile and Not Eating: Is It an Emergency?

It’s 2 a.m. and you just stepped in a puddle of green cat vomit. Your first thought is probably, “Green? Why is it green? Is that a bad sign?” 

Here’s the short answer. The color of your cat’s vomit usually matters less than how often it’s happening and whether your cat is still eating and acting normally. A single episode of vomiting green bile is often not an emergency. But when green bile vomiting is paired with poor appetite, especially if your cat hasn’t eaten for more than about 24 hours, it can signal a more serious problem.

According to Cornell University Feline Health Center, vomiting can result from a vast array of causes from toxin exposure to kidney disease. So how do you tell whether your cat’s situation is urgent or something that can be watched for a short time? The next section will walk you through the key signs veterinarians use to decide when a cat needs prompt care and when it’s reasonable to monitor at home.

Is it URGENT or NON-URGENT?

The big question you should be asking yourself is whether your cat needs to see a veterinarian on an urgent basis or if they can wait a day or two for an appointment. While there aren’t always clear boundaries between who needs to go immediately, I’ll share some symptom guidelines to consider below. 

If your cat has one or more symptoms from the URGENT column, take them to see a veterinarian right away.

Why cats sometimes vomit green bile

It’s true that cats who eat green plants might have greenish vomit. When this is the cause, you’ll often see some undigested plant material in the vomitus, too. This is not usually a big concern unless it’s happening repeatedly.

Bile is the other thing that turns vomit green. Bile is a normal digestive fluid produced in the liver. The normal path for bile is from the liver to the gall bladder to the upper small intestine where it helps break down fats in the diet. 

Bile can flow in the wrong direction, entering the stomach, when the upper intestine is not functioning normally. This can happen when the upper digestive tract is irritated, inflamed, or not moving food forward, as it normally does.

Green bile vomit on its own may not be an emergency. Your actions should be guided by the overall pattern of symptoms as outlined in the previous section.

Does vomit color actually tell you what’s wrong?

People often focus on cat vomit color, hoping it will reveal the cause. In reality, vomit color is usually a low-value clue unless blood is involved.

Here’s a realistic way to think about it:

Vomit color alone rarely tells us why a cat is sick. Duration, appetite, energy level, and other symptoms matter far more.

Causes for cat throwing up green bile not eating

Bile normally flows from the liver into the small intestine to help digest food. Vomiting bile often happens when the stomach and upper intestines are irritated or when a cat has not been eating normally.

Common causes include:

• Gastrointestinal inflammation
• Abnormal movement of food through the GI tract
• Nausea from toxins, parasites or disease 

In some cases, a cat with an empty stomach may vomit bile simply because there is nothing else to bring up. However, persistent vomiting or refusal to eat is not explained by an empty stomach alone.

Why appetite loss is such an important clue in cats

Cats do not tolerate fasting well. When a cat feels nauseated or painful enough to stop eating, it often means the underlying problem is significant. Prolonged poor appetite can also trigger secondary complications, including dehydration and liver stress. 

Home care for your cat

While it is understandable to want to help at home, delaying veterinary care can allow the problem to worsen. These steps are meant to support your cat while you’re arranging for veterinary care, not replace it.

• Keep them comfortable and quiet
• Offer fresh water if they are interested
• Avoid treats or new foods
• Do not give any human medications or supplements unless directed by your veterinarian.

The takeaway

Green vomit gets attention, but color alone rarely tells the whole story. How long the problem has been going on, whether your cat is eating, and what other symptoms are present are far more important clues.

If your cat is throwing up green bile and not eating, a veterinary exam is the safest next step.

Author: TB Thompson, DVM is a veterinarian with 20+ years of experience in clinics, emergency medicine, and community shelters. She started Natural Pets HQ to give pet owners accessible, trustworthy guidance written by a real vet.

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References

1. Cunningham, J. G., & Klein, B. G. (2007). Textbook of Veterinary Physiology (Fourth edition). Saunders.
2. Hall, J. E., PhD. (2015). Guyton and Hall Textbook of Medical Physiology. Elsevier Health Sciences.
3. Kearns, S. (2009). Infectious hepatopathies in dogs and cats. Topics in companion animal medicine, 24(4), 189-198.
4. Simpson, K. W. (2015). Pancreatitis and triaditis in cats: causes and treatment. Journal of small animal practice, 56(1), 40-49.