The best and most effective flea foggers or flea bombs have one or more of these ingredients: cypermethrin, methoprene, nylar, permethrin or tetramethrin. These are the main chemicals that kill eggs and larvae as well as adult fleas.
These chemicals in foggers are dangerous, requiring removal of pets and humans from the house for at least eight hours after their use. Treating the pet first with an oral or topical flea product, then cleaning and vacuuming the home thoroughly and repeatedly can be more effective than using a fogger. Washing all pet bedding and rugs in hot water is a must. Sprays that interrupt the life cycle of the flea and prevent it from reproducing can reach baseboards and cracks that the fogger doesn't reach. Foggers work best in an empty house where the chemicals are allowed to remain undisturbed on the floor for several days.