What Causes Vomiting and Diarrhea in Young Cats?
My five-month-old cat has been throwing up and having
diarrhea for the last four days. It is not all of
the time, but it is 85% of the time. He plays
normally, eats normally and acts the same. If you
have any ideas what could be wrong with him please
let me know. Thank you!
Tessa
Kinderhook, Il.
Many things can cause otherwise healthy young cats to vomit or produce diarrhea. Intestinal parasites are high on the list.
Young animals are especially prone to infestation with intestinal worms and microscopic parasites called coccidia. These parasites are common causes of diarrhea in kittens and puppies. Severe infestations may cause vomiting as well. Some intestinal worms are potentially contagious to humans.
Adverse reactions to rapid diet changes also may cause the sort of gastrointestinal upset that you describe. Foreign objects lodged in the intestines, infection with a number of viruses or bacteria, and inflammatory disorders of the intestines are on the list of causes but are less common.
Your cat needs to see a vet. Be sure to take a stool sample so that he or she can test for parasites. After evaluating your pet and looking at his deworming and vaccination history, the veterinarian will be able to offer an educated assessment of the situation.
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You have questions. 
My cat had intestinal parasites very recently, right at the same time he had cat flu – as you can imagine it knocked him sideways. He couldn’t keep any food down and we only knew he had worms as they were present in his vomit. Naturally, we took him to the vets and he was given a de-wormer spot on which did the trick but the worms left Bobbin craving cat litter (which we sorted) due to a vitamin B12 deficiency. He did have diarrhea for about a day after he was de-wormed but now – two weeks on, he is back to his happy, healthy self again!
My kitties do not have parasites, I do try to watch them very close. However, now that I have read this, I think I will watch even more. Thank you so much for posting this. It was very informitive. I have wondered and worried about the parasites for a long time. I clean the kitty box several times a day, because I am so afraid of them getting sick. I hope it never happens, and like you said, the first sign that they arent acting right, and my kitties will be taking a ride to the vet. Whether they like it or not! Thanks again. Very helpful for readers.
So funny to stumble on this, I have the same exact problem! My 5 month old is also vomiting and has diarrhea at the same time, but is otherwise very active. I am pretty sure there are no parasites, though, because he just came from the vet for his final round of shots and had full blood work and parasite testing done. Can there be any other reason?
My two 5 month old cats suffered from the same symptoms back in December. They were vomiting and had severe diarrhea but were still incredibly active. I thought it was because I changed their food, which can throw the whole balance of their system off. I fasted them as suggested by my vet and they still exhibited the same symptoms. I started to notice spaghetti like pieces in their vomit and realized I was dealing with roundworms. My kittens were strays so they had several problems to begin with. They made many trips to the vets and just as I thought everything was taken care of this issue came up. Roundworms are nasty little parasites. Their eggs can last in the soil for several years so they are easily ingested by other animals and even children. My kitties are indoors and they had the eggs in their systems since they were only 5 weeks old so they were able to stay undetected by the vet since they hadn’t hatched yet. I’m sure by now you have it figured out, I hope. By the time they start throwing these worms up they have a very bad infestation and require immediate attention. They do sell something over the counter but it’s not nearly as potent as the one the vet can administer.