When we got Mandy she had worms. Found them in her stool after we started giving her deworming medication. Thankfully they were already dead. When we went to the vet to get some deworming medication he told us to deworm Hayley again also. We didn't notice Hayley having any but the vet told us it was a good idea because they could be easily passed from one cat to another if they are using the same litter box. Hayley and Mandy had to take the deworming medication 3 times, two weeks apart. The medication is not that expencive and I had loads left. My mother-in-law also dewormed her new kitten with the same bottle.