Why Does My Cat Eat Plants and Throw Up?

I have always owned cats throughout my life, and noticed that one of their favorite outdoor activities is to chomp up grass as soon as they are let out, but soon after, the grass almost always came back up as vomit!

I always had the impression that cat grass is good for cats, and occasionally buy some for my cat Reginald. Over the duration of his plant’s life (not very long), he almost always throws it back up. So, why does my cat eat plants and throw up? Here’s a quick explanation as to why cats do this:

  • Digestive Benefits
  • Compulsion, boredom, and curiosity
  • Instinctual behavior from their wildcat ancestors
  • Contains beneficial vitamins, minerals, and fiber

Why Does My Cat Eat Plants and Throw Up?

  • Digestive Benefits
  • Compulsion, boredom, and curiosity
  • Instinctual behavior from their wildcat ancestors
  • Contains beneficial vitamins, minerals, and fiber

Why Are Cats Driven to Eat Plants Despite Being Obligate Carnivores?

Cats are obligate carnivores, meaning they do best with a diet restricted to meat.

Their meat-only diet, and seemingly getting sick from eating plants, does not stop a cat from eating them, and hasn’t for hundreds of years. So what drives them to do this?

Digestive Benefits

One theory of why cats eat plants is because they intentionally eat it to relieve their upset stomach or constipation.

Grass and other plants contain the complex carbohydrate called cellulose. Unlike cows – cats, dogs and humans do not have the enzyme cellulase to break down cellulose in grass. This makes it very undigestible and as a result triggers stimulation of the stomach muscles to purge anything else undigested in their stomach such as fur balls. So, in this case throwing up is beneficial for cats (especially longhaired cats)!

Grass and other plants can act as a laxative, benefitting cats who are constipated. It has the same benefits of fiber in human diets- helping with the movement of stool. If the plant cellulose goes down far enough the digestive tract, it can make other undigested materials break apart more and therefore easier to pass.


One theory as to why cats eat plants and throw up, is not because they are intentionally trying to reap the digestive benefits, but rather because it is an instinct deeply ingrained in them from their wildcat ancestors.

Your cat’s ancestors ate plants too, even more so for the same digestive benefits. Though these ancestors would be expelling way more than just fur balls, but rather bones, feathers, and parasitic worms. The undigested material from plants stimulate their stomach muscles to contract to expel these intestinal worms- reducing the parasitic load to a tolerable level. This practice became very beneficial for wildcats due to the fact that virtually all of them are infected by intestinal worms acquired from raw meat. Though domestic cats, unless they are outdoor free-roaming cats, are not as prone to intestinal parasites, and do not necessarily need the benefits from eating plants.

Health Benefits

Grass juice from certain grass species are rich in in folic acid (vitamin B9). The benefits of folic acid are: maintains a healthy digestive system, cell growth, and hemoglobin production. Because hemoglobin transports oxygen to tissues, a cat deficient in folic acid can become anemic.

Scientist of the animal nutrition and health organization DSM, explains that folic acid from grass is unnecessary because the bacterial flora in your cat’s stomach produces enough folic acid to meet your cat’s requirements.

Other than folic acid, some plants contain vitamins and minerals often seen in supplements for cats such as calcium, iron, and vitamins A, C, and E. Plants, especially parsley that contains these mentioned vitamins, may be a good alternative to supplements, as a cat’s regular diet may not contain enough of these vitamins and minerals. That is, if your cat is willing to snack on parsley!

Other Reasons Cats Snack on Plants

  • The movement of the leaves or dangling vines entice the cat to play with and bite the plant.
  • Boredom- cats become bored and want to explore and try new things…including the taste and texture of your house plant. Make sure to engage their curiosity and senses in other ways such as puzzle toys, foraging toys, cat grass, and cat trees
  • Compulsion- some cats can develop anxiety and/or obsessive compulsive disorder that can lead to repetitive self soothing actions such as overgrooming, vocalization, and the compulsion to chewing on things. Or perhaps they are stress eaters, and want to fill their stomachs.

Are Plants Safe For Your Cat?

Why Does My Cat Eat Plants and Throw Up?

Is eating plants generally safe for domestic cats? It depends. There are some plants that are toxic to cats and some that provide nutritional and digestive benefits mentioned above. It is also important to consider any pesticides used on your plants, even if they are outdoor plants- in the case you own an outdoor cat. If you cannot identify a plant, it is safe to assume it is dangerous for your cat.

Plants That Are Safe For Your Cat

Although the extent of the health benefits that these plants provide are debatable, they are non-toxic and harmless. Some of these cat-friendly plants are:

  • Spider plant
  • Cat grass (oat grass, barley grass, rye grass, and wheatgrass)
  • Wandering jew
  • Christmas cactus
  • Bromeliads

This is not a complete list. You should always identify and do your research about a plant’s toxicity to cats before bringing it home.

Plants That Are NOT Safe for your cat

According to Poison Pet Helpline and Dr. Lee from Pet Health Network, the following are plants cat owners want to avoid bringing in their home (or even in their back yard).

Lilies are one of the most dangerous plants for your cat to ingest, and it is recommended that you not keep them in your house with a cat because even a few bites of their petal can cause kidney damage/failure. This includes any lily variant.

Besides the lily, here is an incomplete list of some common houseplants as well as plants that grow outside that are toxic to your cat:

  • foxglove
  • lily of the valley
  • kalanchoe
  • Japanese yew
  • Autumn Crocus
  • Azalea
  • Cyclamen
  • Kalanchoe
  • Oleander
  • Dieffenbachia
  • Daffodils
  • Lily of the Valley
  • Sago Palm
  • Tulips and Hyacinths
  • Aloe plant

If you suspect your cat ate a poisonous plant, or you’re not sure about the plant’s identity, immediately remove any plants remnants from your cats mouth, and body. Then keep him in a safe confined area. Call animal poison control ASAP at (1-888-426-4435) before bringing your cat to the vet.

Why Does My Cat Eat Plants and Throw Up Final Thoughts

Cats and their ancestors have been eating plants for hundreds of years. It is believed that house cats eat plants intentionally to help ease their upset stomach and expel fur balls, however, the most plausible explanation is that it is a deeply ingrained instinct acquired from their ancestors. Some cats may continue on with this to ease their stress, boredom, or hunger. Either way it is very important to be careful about what plants are brought home and if you cannot identify a plant, it is safe to assume it’s toxic.

Does your cat have a tendency to eat plants? If so, feel free to comment below with your experiences or any questions you may have! Also feel free to checkout our latest cat health articles here

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