Why Do Cats Eat Grass And Throw Up?

Why Do Cats Eat Grass And Throw Up?

Have you been wondering why your cat munches on grass now and then? While this is not a cause for alarm, cat owners are curious why cats do this especially since after eating grass, cats start to throw up. Read on and let us unravel the reasons for this behavior. 

Reasons why cats eat grass

These are the common reasons why cats eat or consume grass:

1. To relieve constipation.  

Cats are believed to eat grass because it has indigestible cellulose or fiber that they need to maintain good digestion. Felines tend to suffer from constipation and by eating grass they are self-medicating to relieve their colons. However, it does not always follow that cats only eat grass when they are constipated. If you notice that your cat is straining in the litter box, agitated and has not pooped for more than a day, bring her to the vet for treatment. 

2. To extract juices rich in folic acid.

Another probable reason why cats eat or chew on grass is to extract its juice that is rich in folic acid or Vitamin B9. It helps them to produce hemoglobin that transports oxygen in the blood. Mama cats are known to produce folic acid in their milk and cats that consume less of it run the risk of developing anemia. 

However, while some may theorize that cats eat grass due to folic acid deficiency, this does not seem to be the case. Animal nutrition experts note that the bacteria in a cat’s stomach produces adequate folic acid requirements.

3. To relieve anxiety.

This theory indicates that cats eat grass because they are stressed or anxious and that it gives them something to chew on to distract themselves from emotional discomfort. This may be comparable to humans who tend to overeat if they are stressed such as binging on chocolate or ice cream. However, the said theory does not seem to apply to the majority since there are cats with good mental health that enjoy eating grass as well. 

4. It is an instinctual behavior among cats to keep parasites in their stomachs to a tolerable degree. 

A recent study made by scientists in Norway attests that eating grass is instinctual among cats. The study also confirms that cats do not necessarily vomit after eating grass, refuting earlier assumptions that cats only eat grass to throw up due to some stomach discomfort. Scientists note that wild carnivores and meat-eaters eat grass to keep worms in their intestinal tract to a tolerable degree. Similarly, domestic cats eat grass due to instinct although they do not eat live prey most of the time.

5. To make up for the lack of greens in their diet.

Another probable reason is that cats may just be eating grass to make up for the lack of greens in their diet. However, while current science does not support the idea that cats need vegetables and fruits, the said theory indicates that cats also yearn for vegetation in their diet. 

Cats are known as obligate carnivores and they require meat in their diet. They do not have the right enzymes in their bodies to process vegetation like grass properly. Still, most felines tend to eat grass for reasons discussed above. 

Why do cats eat grass and throw up?

These are the probable reasons and theories why cats eat grass and throw up:

To eliminate indigestible stuff from their stomach.

Cats are believed to vomit because it makes them feel better, regardless if they are feeling ill or not. What fuels this theory is the idea that undomesticated cats that do not eat food from a can would eat their prey whole which includes its bone, fur and feathers. Thus, they vomit to remove indigestible stuff like bones from their bellies.

They may not be feeling well. 

Another reason why cats eat grass and throw up is that they are not feeling well. A cat may be eating grass due to an inflammatory bowel disease or because of a food allergy resulting in gastrointestinal distress. They may be doing it to ease discomfort and being able to vomit after eating grass may be a cat’s way to self-heal from such conditions. 

However, most cat experts refute the above theories since it was observed that perfectly healthy cats with no gastrointestinal woes also eat grass and throw up. Cats also tend to vomit and regurgitate although there were no signs of fur or bones from their belly. 

What to do if you notice your cat eating grass?

Here are some measures that you can do if your cat is eating grass:

  • Do not let your cat consume old grass.
  • Keep poisonous house or landscape plants like giant dumb cane and hurricane plant away from your cat.
  • Propagate cat grass or catnip indoors that your cat can safely chew or eat.
  • Be mindful of the herbicides and fertilizers that you are using in your garden and potted plants. 
  • Consider putting up an indoor cat garden for your cat that consists of safe and untreated grasses like wheat or barley.
  • Watch out for grassy foreign body that may enter your cat’s sinuses as it may cause excessive sneezing and nasal discharge  

You may also check our earlier article on why is my cat eating paper for additional information on cat’s weird eating behaviors.  


Cats have unique personalities with a penchant for weirdness at times. They chew and eat grass just to vomit it out eventually. While this may not be a cause for concern, it is best to bring your cat to the vet for a thorough assessment especially if there are other health concerns involved. 

Image: istockphoto.com / kozorog