Most flea preventatives are only meant to kill the fleas on your pet, not in your home. And since adult fleas are only 5% of a flea infestation, what you see on your pet is only half the battle. Flea eggs, larvae and flea cocoons aren't easy to get rid of, and only products formulated to target these stages of the flea cycle can help in truly eliminating a flea infestation.
Having fleas in your home is certainly a thought one would rather not think of. However, below is an example of where most fleas reside in an infestation.
In short, you MUST treat your home and yard to truly get rid of fleas.
When an adult flea lays eggs, it forms a hard cocoon-like shell, called the pupae, which is impossible to kill with even with the strongest carpet spray. You can only kill the pupae once they hatch into adult fleas. Pupae hatches 3-4 weeks after you first treat your home. That is why it is important to treat your home again in 3-4 weeks.
Fogging your home helps to kill the pupae since the residual effects from foggers usually last months after your first treatment. Just remember, foggers can be dangerous, be sure to follow the manufacturer's instructions.
In addition, fleas are hitch hikers and attach to your shoes or clothing. So you must treat your yard or you will continue to have fleas in your home.
For best results, always wait 24 hours after applying a topical flea preventative before you wash your pet. Even then, use a gentle shampoo that will not rinse off preventative.