Capstar is pretty effective, I personally would not do comfortis since she is still young. I have used flea busters for years it is a powder that you put into the carpet, pet beds, in sofa in the back where they like to live. You can lookm it up and order it online, it is messy but it works. I never use flea meds on chester, good luck. I also use flea buster powder in my vacum or cut up flea collar if you dont empty it every time |