Common Flea Insecticides
and How They Work

"Choose the least toxic insecticide possible to do the job and to keep your cat safe and healthy."

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Flea Insecticides Can Harm Your Cat!

Flea insecticides in conventional flea control product ingredients, and even some "natural" flea control products, can be dangerous to your cat's health.

Flea product manufacturers have worked over the years to try to make flea control products safer for pets. The ideal flea control product contains an insecticide that is toxic to the flea and safe for your cat and for you. 

Before you choose a product to get rid of fleas on your cat or in your home, you should know the type of insecticide being used in the product  and its possible side effects on your cat or kitten's health. 


Follow Label Directions Carefully!

Whatever products you choose to use to get rid of fleas, you must follow the directions precisely for your cat's protection and yours. More is not better in this case, and may even be deadly to your cat! 

Do not mix flea control products or use several products at one time, unless under your veterinarian's supervision. The collective effect of too many products can kill your cat! And never use a flea product that is made for dogs only. 


List of Common Flea Control Insecticides

The following is a list of common flea insecticides and a brief description of how they each work. 

Insecticides Previously Requiring a Prescription

Note: These popular medications used to require a veterinary prescription. However, they can now be bought over-the-counter (and online) and no longer require a veterinarian's prescription. 

Lufenuron is the active ingredient in Program®. It can be given orally once a month or by an injection every six months. It does not kill the fleas already on your cat, but instead prevents flea eggs from developing. Interrupting the flea life cycle is an effective long-term way to control fleas on your cat and in your home. This product is suggested for cats who are not allergic to flea saliva, as it does not prevent adult fleas from biting your kitty. 

Fipronil is the active ingredient in Frontline®. It's a topical insecticide. It kills fleas on contact and is supposed to be effective on your cat for one month. The manufacturer (Merial) says that it's safe for kittens over twelve weeks old. 

Imidacloprid is the active ingredient in Advantage® Flea Control. It's a topical insecticide that you apply between your cat's shoulder blades. It kills fleas on contact and lasts for a month. (This is the product I've used for my two healthy cats when they've needed quick relief.) 

No Veterinary Prescription Required

Methoprene (e.g., the brand, Zodiac®) is an insect growth regulator. It's used in foggers, sprays, shampoos, and collars. It targets flea larvae and keeps them from maturing and reproducing. Methoprene is considered to be nontoxic, but it's usually combined with toxic chemicals to kill adult fleas. It's not very effective outdoors. Visit the Zodiac® manufacturer's website for more information. 


Borates (boric acid derivatives) are found in flea control powders for use on carpets and other places in your home. Borates kill adult fleas, flea eggs, and larvae by removing the moisture from their bodies. These are supposed to have low toxicity and are reported to be very effective for up to one year. (I've tried Fleabusters Rx a couple of times over the years and find that it works remarkably well.) 

Pyrethrin-based products are derived from chrysanthemum flowers. Of all the chemicals, this "natural" insecticide is thought by some to be one of the safer flea control chemicals on the market. These products are thought to be safer than those containing, for example, carbamates and organophosphates.

If pyrethrins are used, some veterinarians recommend micro-encapsulated rather than natural pyrethrins. Microencapsulation is the use of a thin nylon or urea shell around minute bits of insecticide. The process is used for sustained release and longer action. It's also supposed to reduce the toxicity of flea insecticides to your cat because the tiny capsules pass through your cat's intestines before all the contents are absorbed. 

Pyrethrins can be found in sprays, powders, shampoos, and foggers. When using a spray with this insecticide, it's best not to spray your cat directly as this may frighten him. Instead, spray your fingers and then work them through your cat's fur. 

Organochlorines are less immediately toxic than organophosphates and carbamates and have largely replaced them, but these flea insecticides accumulate in tissues and persist for years in the environment. 

Choosing the Safest Product

cat veterinarian

It's always best to choose the least toxic method available to get rid of fleas.

Although modern flea insecticides have been improved for safety and have lower toxicity than those used in the past, there is still some level or toxicity that you should take into consideration for your cat's health and other pets. 

Natural flea control methods are safer, but if you decide you need an insecticide, you now have knowledge about the toxicity and possible side effects of flea insecticides. You should be able to make the best choice to get rid of fleas and keep your cat healthy.

If you have any doubts, consult your trusted veterinarian.


Recommendations for Discount Flea Medication Online


Amazon has a broad selection of conventional flea medications, such as Advantage, Program, Frontline, etc. Prices are a fraction of what you would pay at your vet's office.


Only Natural Pet Store has the best selection of natural flea control products and the best customer service on the internet.



Related Feline Articles

Didn't find what you're looking for? Use this Search Box to find more information. Or visit the articles below.



* Conventional Flea Control - Essential information to get rid of fleas.

* Carbamates - Toxic side effects to look for.

* D-limonene - Info on this natural citrus extract found in flea shampoos.

* Organochlorines - Toxic side effects to beware of.

* Organophosphates - Side effects to watch for in your cat.

* Pyrethrins - Information on side effects.

* Rotenone - Dangers of this insecticide.


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