Kittens vomiting white mucus may be caused by improper diet, indigestion, internal parasites, colds, gastrointestinal diseases, or stress reactions. If the kitten also has diarrhea, poor energy, bloody stools, and incontinence, If the kitten does not eat or drink, it is best to send it to a pet hospital for examination. If the kitten has no other abnormalities, you can first deprive the kitten of food and water, and then feed it some probiotics.