Are you using one of the popular, 'applied monthly' flea products? Think about it...it can kill fleas because it is a form of poison. Some products contain strychnine. Others have the active ingredient, imidacloprid which is rated as "moderately toxic" acutely by the WHO and the EPA and which causes thyroid lesions in rats. Is that really something you want to apply to your dog between his/her shoulders once a month to be absorbed by his/her skin until it's able to also poison every flea that comes into contact with him/her?
There are wonderful, affordable essential oil combinations made especially for repelling fleas. Most contain oil of lemon and eucalyptus- very pleasant smelling.
Diatomaceous earth is an inexpensive, natural remedy for flea infested areas of the home or yard. All can be found online.
Wishing you vibrant health and
Nadine (and Buttons)