Flea bombs, also known as foggers, dispense flea-killing chemicals in aerosol form in homes. Flea bombs are completely safe to use if you have a puppy as long as he isn't inside your house while the fogger's doing its flea-eliminating business.
Leaving the House
Just before you set off the flea bomb, get Rex ready to go -- collar on, leash attached, the whole 9 yards. Soon as you activate the fogger, get your butts outside immediately. Most foggers require you to stay out of the house for two to four hours. You'll likely have to chill out at a park, with lots of fresh water at hand, or somewhere similar, since you can't bring Rex and his fleas to someone's house. When you return home, open up some windows and power on a fan or two to help ventilate the area.
Flea bombs address the problem of blood-sucking fleas inside your home. They do nothing for the fleas that infest your pup. Without preventing fleas in the first place, those on your dog will reinfest your home. Talk to your vet about Rex's fleas prior to bombing your house. Oral and topical medications are the most common ways to ward off the parasites.