Flea shampoo works fine for cats — for a while. But here's a way to make absolutely sure that you remove those fleas and then keep them off for good.
Simmer two cloves of garlic on the stove until they are translucent and the water looks like the equivalent of garlic powder. Remove from heat and leave the pot until the mixture has cooled. After giving your cat its normal flea bath — leaving the shampoo on for at least five minutes before rinsing so you kill all of the fleas and eggs — slowly pour the garlic solution over your cat, concentrating especially on its belly and hind quarters. After this garlic bath you will have a happy flea-free cat.