Do Cats Eat Grass When Sick? The Myth vs. 4 Real Reasons

• The Verdict: Occasional grazing is normal and usually safe for healthy cats.
• The Why: It is an evolutionary instinct to aid digestion, expel hairballs, or supplement trace vitamins like Folic Acid.
• The Risk: Lawn chemicals (pesticides) are the real danger, not the grass itself.
• When to Vet: If your cat eats grass daily or vomits without bringing up hairballs/objects, see a vet immediately.

1. The Purge Mechanism (Nature’s Detox)

Cats lack the enzymes to digest raw grass. When they eat it, the texture irritates their stomach lining, intentionally triggering a vomit. This helps them expel:

• Hairballs: Indigestible fur from grooming.
• Parasites: In the wild, grass fibers wrap around intestinal worms to flush them out.
• Inedible Objects: Feathers, bones, or that bit of plastic they swallowed.

2. Identifying a Nutritional Gap (Folic Acid)

Some experts suggest cats graze to correct a deficiency in Folic Acid (Vitamin B9), which is essential for oxygen levels in the blood. While modern high-quality diets usually cover this, the ancestral instinct remains.

3. Relieving Constipation

Think of grass as a natural fiber supplement. For cats that aren’t vomiting it up, the fiber acts as a laxative to help bulk up stool and speed up digestion, making it easier to pass.

4. Boredom & Texture (Psychological)

Sometimes, it’s not medical—it’s mental. Indoor cats may chew plants simply because they crave a new texture or are bored.

• Boredom and Enrichment: For indoor cats, the world is smaller. Lacking mental stimulation, they may graze on plants for enrichment. Chewing on interesting textures can be a way to alleviate boredom.
• The Ancestral Drive: Even without hunting, the biological drive to “purge” or clean their system remains. Their body simply tells them to graze.
• The Houseplant Danger: Indoor cats often target whatever greenery is available. This leads to chewing on toxic houseplants like lilies. If your cat eyes your ferns, they have the urge to graze, and you need to intervene with a safe alternative.

Here is the reality: Eating grass doesn’t automatically mean your cat is ill. Many healthy cats enjoy it. However, cats may learn that it soothes a sore throat or settles a stomach.

If your cat is happy, grazing is likely just a quirk. But if the behavior becomes obsessive and is accompanied by lethargy, weight loss, or strange behavior, it could signal issues like inflammatory bowel disease (IBD).

Because they lack the necessary enzymes to digest raw plant matter, grass acts as an irritant to the stomach lining.

This is often intentional. The irritation triggers vomiting, which acts as a mechanism to clear the stomach of indigestible items such as hairballs (trichobezoars), feathers, or bones. It is essentially a “system reset.”

• Grow Your Own Cat Grass: Provide safe wheatgrass, oat, or barley grass indoors. This satisfies cravings without the risk of lawn chemicals and saves your houseplants.
• Dietary Changes: If they eat grass to vomit hairballs, switch to a high-fiber hairball control diet or use gel supplements. Helping them pass hair naturally reduces the urge to vomit.
• Enrichment: Combating boredom? Increase playtime with puzzle feeders and feather wands to distract them from greenery.

• Vomiting is frequent (multiple times a day).
• Only liquid or blood comes up (no hairball or grass).
• The behavior is sudden, obsessive, and daily.

These may indicate gastrointestinal issues that a simple patch of wheatgrass can’t fix.