Why Is My Cat Suddenly Not Eating

If your cat was eating normally and has suddenly stopped, it's understandably alarming. Sudden appetite loss is different from a cat that's always been a picky eater — it's a significant change that warrants prompt attention. Here's what sudden food refusal usually means and what to do about it.

Sudden vs. Gradual Appetite Loss

The distinction matters:

Sudden appetite loss (eating normally yesterday, refusing food today): More likely to have a medical cause; requires faster action
Gradual appetite loss (eating less and less over days or weeks): Can be medical or behavioral; still requires investigation

This article focuses on sudden appetite loss — when a cat that was eating well abruptly stops.

Most Common Causes of Sudden Appetite Loss

1. Acute Illness or Infection

The most common cause of sudden appetite loss is an acute illness — a respiratory infection, gastrointestinal upset, urinary tract infection, or fever. Cats instinctively reduce food intake when they feel unwell. Look for other symptoms: sneezing, runny eyes, vomiting, diarrhea, lethargy, or hiding.

2. Something They Ate

If your cat ate something that disagreed with them — a new treat, table scraps, a plant, or something they found outside — nausea and appetite loss can follow. This usually resolves within 24 hours if the cause was mild.

3. Vaccination Reaction

It's very common for cats to have reduced appetite for 24-48 hours after vaccinations. This is a normal immune response and typically resolves on its own.

4. Medication Side Effects

Many medications — antibiotics, pain medications, chemotherapy drugs — cause nausea and appetite suppression. If your cat recently started a new medication and stopped eating, contact your vet about anti-nausea options.

5. Stress or Sudden Environmental Change

A sudden change in the household — a new pet, a new baby, a move, a visitor, loud construction, or even rearranging furniture — can trigger acute stress that suppresses appetite. Cats are extremely sensitive to environmental disruption.

6. Food Change or Spoilage

Did you open a new bag or can? Dry food can go rancid, and wet food can spoil. Cats detect this immediately even when humans can't. Check the expiration date and try a fresh portion from a different container.

7. Dental Emergency

A broken tooth, abscess, or severe gum inflammation can cause sudden, acute pain that makes eating impossible. Look for pawing at the mouth, drooling, or dropping food.

8. Urinary Blockage

A urinary blockage — especially in male cats — causes rapid deterioration including appetite loss, lethargy, and straining to urinate. This is a life-threatening emergency requiring immediate veterinary care.

9. Toxin Ingestion

If your cat has ingested a toxic plant, household chemical, or medication, appetite loss may be one of the first signs. Other symptoms include drooling, vomiting, tremors, or collapse. This is an emergency.

What to Do Right Now

Check for other symptoms: Lethargy, vomiting, diarrhea, straining to urinate, hiding, or pain are red flags requiring immediate vet attention
Try warming the food: Warm wet food to body temperature to enhance aroma
Offer something highly palatable: Fancy Feast Gravy Lovers is often irresistible even to cats with reduced appetite due to its rich gravy aroma
Check the food: Smell it yourself; check the expiration date; try a fresh portion
Reduce stressors: Provide a quiet, safe space for eating away from household activity

The 48-Hour Rule

If your cat hasn't eaten for more than 48 hours, contact your vet regardless of whether you can identify a cause. Cats can develop hepatic lipidosis (fatty liver disease) within 24-72 hours of not eating — a serious, potentially fatal condition that requires medical treatment. Don't wait and hope it resolves on its own.

Emergency Signs: Go to the Vet Now

Straining to urinate with little or no output (especially male cats)
Collapse or extreme weakness
Suspected toxin ingestion
Seizures or tremors
Severe vomiting or bloody diarrhea
Kitten not eating for 12+ hours

Final Thoughts

Sudden appetite loss in a cat that was previously eating well is always worth taking seriously. While some causes are benign (vaccination reaction, mild stress), others require prompt medical attention. When in doubt, call your vet — it's always better to check and find nothing serious than to wait and miss a treatable condition.

Back to blog