Garlic will screw up your pets digestive system, dont want to risk a huge vet bill or even death, might as well buy the most expensive flea killer.
I buy capstar, they sell it at the vet for 30 bucks a box or 5 dollars a pill, fleas are coming off and dying within thirty minutes, by the end of the day most to all are off, if not, you can use another pill as early as the next day. The pills releases something off the dogs skin which acts like poison. It may not be a home remedy, but bathe your pet in dawn soap and then use that pill and you should be good to go ^.^