Drooling in cats can be due to a wide range of conditions; in this case, nausea and sickness due to being ill OR stomatitis (inflammation of the inside of the mouth). In some cats with calicivirus, the stomatitis comes before the eye or nose signs, and that might be going on here.
If your cat is drooling, it could be that they're ill, says Dr. Ethan Nunnally, DVM, of Large & Small Animal Medicine & Surgery, Animal Health Center of Albia, Iowa. "Cats drool when they are in pain," he says. "Your cat might have stomatitis, an inflammation of the mouth and lips.
Drooling paired with a loss of appetite is almost always a sign of oral pain or underlying illness. Common causes include dental disease, mouth ulcers, toxin exposure, or gastrointestinal issues. You should contact your vet within 24 hours if your cat stops eating.

Cats are creatures of comfort, and when they are in a state of pure bliss, such as when they are being petted or are lounging in a favorite sunny spot, they may drool slightly. This type of drooling is often referred to as "happy drooling" and doesn't need any medical attention.
Cat drooling can range from harmless behavioral responses to serious medical emergencies, making it essential for every cat owner to understand the underlying causes. Unlike their canine counterparts, cats typically dont drool unless something specific triggers the response.

Here are some reasons your cat might drool too much, along with suggested treatments. Mouth disease and tooth decay. Tartar buildup can rub on the inside of your cats lip, causing them to slobber. To check, pull their lip back toward their ear.
Light drooling during purring, kneading, petting, or deep sleep can be normal in some cats. New drooling that keeps returning is not a typical pattern and should be checked. Bad breath, mouth pain, sneezing, vomiting, appetite loss, or unusual behavior make drooling more concerning.