Imidacloprid 

Imidacloprid is one of the newer insecticides. Like others, it acts on the nervous system of insects.

Though it’s able to kill fleas fast, it has practically no effect on ticks.  It is applied topically onto pets where it gets absorbed into the hair follicles and released slowly over a period of time. With such extended effects, it needs only to be applied once every month making it very convenient for use. It also has a high margin of safety but like all others insecticides, some pets may still develop sensitivity to it.

The most popular product containing Imidacloprid is ®Advantage

Fipronil 

Fipronil is also one of the newer synthetic insecticides to be used. It acts by causes nerve paralysis in insects like fleas. Just like Imidacloprid in Advantage, fipronil gets collected into hair follicles of pets and then released slowly over a period of time. This enable it’s effect on fleas to last for a month or more.

One advantage of Fipronil over Imidacloprid in Advantage is that it is also active against Ticks.  A relatively safe insecticide for use but some pets have been reported to develop sensitivity to it.

Product containing Fipronil: ®Frontline and Frontline Plus

Selamectin

Selamectin kills parasites by blocking nerve signal transmissions. Selamectin when applied onto pets will enter the bloodstream through the skin. The effect of Selamectin is threefold once it got absorbed into the bloodstream Firstly, it stays in the bloodstream protecting against heartworm disease, Secondly, it then passes into the gastrointestinal tract whereby it kills certain intestinal parasites, and finally, it will passes into the sebaceous glands in the hair and skin providing protection against fleas and certain mites and ticks.

With its “triple” actions, Selamectin is a popular choice used in the treatment and prevention of fleas, ear mites, ticks and heartworm diseases.

Overall, Selamectin is safe for use in healthy adult dog and cats but not on kittens or puppies and also sick, elderly pets.

Product containing Selamectin: ®Revolution

Insect growth regulators & development inhibitors

Insect growth regulators (IGRs) include both insect growth inhibitors (IGI) and insect development inhibitors (IDI). These are the relatively new range of insecticide to be included in flea and tick products.

Insect growth inhibitors include Methoprene, Fenoxycarb, and Pyriproxyfen (Nylar). Insect development inhibitors include lufenuron and diflubenzuron.

Unlike other insecticides used in flea products where they act mainly on the adult fleas, IGI and IDI acts on the immature forms of fleas instead.

The IGI will prevent the maturing of the flea larva into adults while the IDI will inhibit the synthesis of a substance called chitin needed for the formation of the skin cuticle.

Because of its action on the immature forms of fleas and not on the adult fleas, it is recommended that it be used together with any of the insecticides mentioned above instead of alone. 

As the effect of IGI and IDI are only on growth hormones and chitin in insects, it is considered an extremely safe product for use.

IGIs and IDIs are mainly used as an active ingredient in foggers, sprays or as an oral tablet or injection administered to cats and dogs.

Products containing IGRs and IDIs (commonly known as the flea pills for dogs or cats)

Program oral tabletSentinel

Biospot Flea and Tick Spray

Adams Flea & Tick Mist for Cats and Dogs (32oz)

Preventic Plus Flea and Tick Collar

Frontline Plus

This should provide you with some ground knowledge in making an informed decision when choosing a suitable flea and tick medicine for your pet. For more details on the individual products, make sure you check out the section on “Flea Medicines".

* Disclaimer: This is meant to be a guideline for pet owners. We will not be responsible for any ill effects that pets may suffer in using any of the products listed in this article. When in doubt, please consult your veterinarian.