So I found out my cat got fleas, I've treated her with frontline around 12 this afternoon, I've noticed a few have started to fall off her (alive) is this right? Will they die even though they've left her body?
It will take a while to kill them all most of them wont be on your cat the ones that jump on and bite will die. I would get some flea traps to get rid of the rest.
They fleas you are seeing are dying. It takes 24-48 hours for all the fleas to die, so have patience. You will need to treat her three months in a row for full control though, so that when the eggs in your carpet etc. hatch they will jump on her and die.