There are more flea and tick products available today than ever before. Provided below is a brief description of the various categories of active ingredients found in today's flea and tick preventives. Also see our
Flea & Tick Product Comparison Chart, which provides a more detailed overview of products containing these ingredients.
Insect Growth Regulators (methoprene, pyriproxyfen (Nylar™), fenoxycarb) -
Insect Growth Regulators (IGR's) differ from traditional flea product ingredients because their main activity is against the immature forms of the flea, not the adults. IGR's mimic juvenile growth hormone, a substance that keeps the flea from developing. Normally, juvenile growth hormone decreases over time and the flea eggs and larvae mature. IGR's keep this development from occurring and the immature fleas fail to molt and they die. Insect growth regulators are found in products such as K9 Advantix® II,
Bio Spot® Defense Spot On® for Dogs, and
Bio Spot Defense Spot On® for Cats. Because IGR's do not kill adult fleas, it is important to make sure that the product you are using also contains an adulticide.
Insect Development Inhibitors (lufenuron, diflubenzuron) -
Insect Development Inhibitors (IDI's) inhibit the synthesis of a substance called chitin. Chitin is necessary for the formation of the hard outside layer (cuticle) of the flea. Without chitin, flea eggs and larvae cannot develop normally, and they die. Lufenuron, an IDI, is found in the flea preventive
Program. Program is not effective against adult fleas, or against ticks, but it can be used with an adulticide that does not contain and IGR or IDI
Pyrethrins, made from extracts of chrysanthemum flowers, have been in use for over 100 years and are common ingredients in flea and tick control products such as Drs. Foster and Smith Flea & Tick Shampoo. Pyrethrins affect the nervous system of insects by influencing the flow of sodium out of nerve cells. This results in repeated nerve firing, and the insect dies. Pyrethrins are used to control ticks, fleas, lice, and mosquitoes.
Pyrethroids (permethrin, phenothrin, etofenprox, fenvalorate) -
Pyrethroids are synthetic relatives of natural pyrethrins. They are made in a laboratory and have a longer-lasting effect than pyrethrins. Examples of pyrethroids include permethrin (found in
K9 Advantix II) and etofenprox (found in
Bio Spot Defense Spot On for Dogs). Pyrethroids are often used in the environment to kill and repel ticks, fleas, lice, and mosquitoes. Many pyrethroids cannot be used on cats, so be sure to check the label for safety. Etofenprox
(Bio Spot Defense Spot On® for Cats) is a pyrethroid that is labeled safe to use on cats.
Fipronil (found in
FiproGuard, and PetArmor is the most commonly used ingredient in a relatively new group of synthetic insecticides called arylheterocycles. These compounds block the passage of chlorine through cells in the insect's nervous system, causing paralysis. In
FiproGuard and PetArmor, fipronil is mixed with an oil carrier, and collects in the sebaceous (oil) glands of the skin, then is slowly released. Because of this, it is water-resistant. Fipronil gives excellent protection against ticks, and adult fleas, but does not prevent flea eggs and larvae from developing.
Imidacloprid (found in
Advantage II and
K9 Advantix II) interferes with the nerve conduction system of insects, by blocking the insects' nerve receptors. It kills fleas but does not have activity against ticks. Therefore, the dog product
K9 Advantix II also contains an ingredient (permethrin) that works against ticks. Advantage II may be used on
cats or dogs, but K9 Advantix II should NOT be used on cats.
Amitraz is an ingredient that is used as a dip to treat demodectic mange. It has also been shown to be highly effective as an ingredient in canine tick collars, such as
Preventic collars. Most ticks are killed by Amitraz before they attach or if they do attach, they are killed in less than 24 hours, thus preventing the transfer of Lyme disease. Do NOT use Amitraz on cats.
Selamectin is the active ingredient in the prescription product
Revolution. Selamectin kills parasites by blocking nerve signal transmission. Revolution is absorbed through the skin and enters the bloodstream, where it protects against heartworm disease. It passes into the gastrointestinal tract where it kills certain parasites, and passes onto the hair and skin providing protection against fleas, and certain types of mites and ticks.
Nitenpyram is the active ingredient in
Capstar, an oral flea control product. Capstar starts killing adult fleas on your pet within 30 minutes. It can be used on pregnant or nursing dogs and cats, and is safe for puppies and kittens 4 weeks and older. It can be very useful in situations such as prior to surgery, boarding or grooming or after a trip to the park. However, it will not work for ongoing control as the medication is out of the animal's system within 24 hours. Therefore, we recommend following up a day later with an application of
K9 Advantix® II.
Spinosad is derived from a naturally-occurring bacterium in the soil. When the flea is exposed to this fast acting insecticide, it over-stimulates the insect's nervous system, causing death. Comfortis, which contains spinosad is a prescription product effective against adult fleas.
Citrus Extracts (Linalool, d-limonene) -
Citrus extracts are derived from the fresh peels of citrus fruits, and have an effect on the nervous system of insects. Linalool is one of the ingredients in Bio Spot® Carpet Powder.
Sodium lauryl sulfate -
Sodium lauryl sulfate is a detergent-like nontoxic flea and tick ingredient.
Synergists (piperonyl butoxide, N-octyl bicycloheptene dicarboximide (MGK 264)) -
Synergists are compounds that help to increase the effectiveness of another active ingredient in a product. For example, piperonyl butoxide helps slow degradation of pyrethrins by the insect's metabolism. Both piperonyl butoxide and N-octyl bicycloheptene dicarboximide are used to enhance the effectiveness of pyrethrins.