What green vomit usually is
Bile is a digestive fluid made by the liver and stored in the gallbladder. It is yellow to green, and when it ends up in vomit it often looks yellow, yellow-green or green. Bile appearing in vomit commonly means the stomach was mostly empty when your cat vomited, but it can also reflect other problems. Green vomit can also come from eating grass, plants, or coloured material, so look at what else is in it.
Possible causes
- An empty stomach. Long gaps between meals, especially overnight, can leave bile irritating the stomach. Some cats vomit bile regularly in the early morning, which vets sometimes call bilious vomiting syndrome. It is a diagnosis for your vet to make after ruling out other causes.
- Eating grass or plants. This can produce green, leafy vomit. Some plants are toxic to cats, so check what is growing in or around your home.
- Gastrointestinal inflammation. Conditions such as gastritis or inflammatory bowel disease can cause repeated vomiting.
- Blockage or slow movement of the gut. Bile-stained vomit in a cat that is repeatedly vomiting can be associated with problems further along the digestive tract, and needs prompt attention.
- Systemic illness. Kidney disease, liver problems, pancreatitis and an overactive thyroid can all cause vomiting. See old cat throwing up a lot for the senior cat angle.
- Stress or toxin exposure. See can stress make a cat vomit; if a toxin is possible, contact a vet or poison helpline immediately.
What vomit colour can and cannot tell you
Colour offers clues but rarely gives a diagnosis. Some general points:
- Yellow or green often involves bile.
- White foam often means little food in the stomach; see cat throwing up white foam.
- Red, pink-tinged or dark coffee-ground-looking vomit may contain blood and should be checked by a vet promptly.
How your cat is acting matters more than the colour alone.
Warning signs
Contact a vet promptly if green vomit comes with:
- Repeated vomiting or inability to keep water down
- Lethargy, weakness or hiding
- Loss of appetite
- Belly pain or swelling
- Diarrhoea
- Blood in the vomit
- Possible swallowing of a toxin, plant or foreign object
- A kitten, senior or sick cat; see kitten throwing up yellow liquid for kittens
What to do
For a single episode in a bright cat who is eating and drinking, observe closely and keep water available. Avoid human medication. Talk to your vet about feeding schedule; for cats who vomit bile on an empty stomach, they may suggest smaller, more frequent meals or a late-evening snack. Do not withhold food for long periods without advice, particularly for cats with other conditions.
If your cat is not eating (see how to get a cat to eat), do not wait many days. Cats that stop eating can develop other problems, so call your vet if appetite has not returned after about a day.
What the vet may do
Expect questions about timing, diet and behaviour, plus an examination. Tests may include blood work, imaging and a faecal check. Treatment depends on the cause and might include anti-nausea medicine, fluids or diet changes.
Prevention
- Keep mealtimes regular and avoid long gaps
- Remove toxic plants and small objects
- Introduce food changes slowly
- Keep up with routine vet visits
Frequently asked questions
Is green vomit always bile?
No. Plants and other material can colour vomit too. Your vet can help if you are unsure.
My cat has diarrhoea but a good appetite. Should I worry?
Diarrhoea with vomiting is worth a call to your vet, even when appetite is good.
How long can a cat go without eating?
There is no safe number to rely on. Call your vet if your cat has not eaten for about 24 hours, and the same day for kittens, seniors, overweight or sick cats.