Have House Fleas or Pet Fleas? Some flea treaments could be more harmful than the flea.


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Flea collars, flea foggers, carpet powder, and flea baths were once the standard routine for pet owners battling their dogs’ and cats’ fleas and resulting house fleas.  And many pet owners, having grown up with these methods, still buy these flea products as well as using the newer spot-on flea treatments available at any pet store. Spot-on flea products get applied to the area behind the pet’s neck. However, many of these flea products are known to cause harm to pets and have many concerned about their effect on humans as well, especially for young children.

Pesticides vs. Insect Growth Regulators (IGRs)

There are two basic types of flea treatment products, insecticides and insect growth regulators. The insecticides are the concern. Many products such as flea collars, some spot-on treatments, and flea foggers used to kill house fleas contain different types of toxins such as pyrethrins, propoxur, or organophosphates. These pesticides most often work by damaging the nervous system of the insect, in this case the flea and thus killing the flea.

With these pesticide products, there is also potential for damage the nervous system of the pets. After years of wearing flea collars, many veterinarians started seeing older cats with central nervous system problems. It’s also not uncommon for pets to show signs of illness immediately following the use of pesticide type flea products. Symptoms can include lethargy, difficulty walking, and excessive drooling.

But the concern does not stop with your cat or dog. It’s possible there’s a risk for humans, both adults and children, exposed to insecticide flea products. The pesticide propoxur is a carcinogen that in California requires a warning label for humans. The Natural Resources Defense Council reports that these pesticides “introduce into the home include chemicals that are hazardous to the human brain and nervous system, chemicals that may disrupt the human hormone (endocrine) system, and pesticides suspected of causing cancer.” Using pesticides flea treatments is especially concerning around small children that put their hands, toys, and yes sometimes their pet’s fur, ears, and tails into their mouths.

Growth Inhibitor Flea Treatment Products

Several flea treatment products on the market are considered safer for the pets and humans by veterinarians and organizations such as the Natural Resources Defense Council. These are the insect growth regulators, such as Frontline Plus, Advantage II, Sentinel, and Revolution. These are not considered pesticides, as they do not kill the flea on contact with a chemical. Instead, these products mimic specific insect hormones that prevent the egg and larvae from making chitin. Chitin is needed to create the insect’s exoskeleton. Since mammals do not have chitin or exoskeletons, the risk of toxicity is considered lower for pets and people. However, you should still use caution when applying even “safe” dog or cat flea treatments or treating for house fleas. Always read and follow the label’s instructions and don’t allow children to play with pets that have just had their flea treatment applied.

Regulation of Flea Products

Pet owners should be aware that just because a flea treatment product is sold “over-the-counter” does not mean it is the safest option. Most of these products are considered pesticides and not medications. Therefore, most are regulated as pesticides and just like pesticides meant for your home and yard, there are few restrictions on purchasing these products. This makes the flea section of a pet store not much different than the pesticide section of your home improvement store.

Treating your dogs’ and cats’ fleas and house fleas is part of good pet care. Fleas can be a minor nuisance to your pet or cause serious skin problems and even anemia. However, there are many options for treating fleas naturally and more safely for your pets and your family than using the old methods of applying pesticides to your pets and home. When starting a new flea treatment, always ask your veterinarian for his recommendation.


Natural Resources Defense Council: Poisons on Pets; Health Hazards from Flea and Tick Products