Absolutely not, says author Kathleen Dudley, despite what the commercials say. 

When it comes to the use of pesticides and insecticides for the prevention of fleas and tics on domestic dogs and cats, the safety of the animals and humans has been debated for some time now.  Fleas and tics are no fun for our pets or us especially when they make their way into the house.  However, the wisdom of using known carcinogens on our animals and in our homes is quite dubious.  In this article by Kathleen Dudley, written several years ago but still quite relevant, you will find a wealth of information on what is known about the chemicals that are used in the most common over-the-counter and veterinarian treatments and how they are tested and licensed.  We encourage you to read this article and to pursue other information on this subject before you do something that you and your pet may regret.  There are more natural alternatives that have proven to be as effective if not more effective and far less toxic than what is typically promoted commercially.  The Critters & Me carries several of these alternatives and we are happy to share our experience in using them with you. Article link below: