What Is in Flea Medication?

Many dogs may have to take flea medication at some point.

Getting rid of fleas often requires a number of different ingredients in order to kill not only the adult fleas, but also larvae and eggs. Flea medication ingredients for dogs can vary, depending on the product and use of the medication. One of the reasons side effects occur with flea medication is incorrect application, so always follow your vet's instructions or those listed on the product.

Pyrethrins

One of the most common ingredients in flea medication, pyrethrins kill adult fleas by affecting the fleas' nervous systems. Pyrethrins are made from natural extracts of chrysanthemum plants and are easily hydrolyzed when digested, so toxicity is very rare. Symptoms of toxicity include drooling, shaking and vomiting.

Pyrethroids

Pyrethroids (permethrin, phenothrin, etofenprox, fenvalorate) are synthetic compounds and act like pyrethrins by affecting the nervous systems of fleas, killing and repelling the parasite but with longer-lasting effects. Some animals may have sensitivity upon application of the flea medication, and while toxicity is slightly higher for pyrethroids, the majority of dogs have no side effects from this compound. Pyrethrins and pyrethroids should not be used on cats.

Fipronil

Fipronil is a common insecticide used in flea medications that causes paralysis in fleas, but does not prevent larvae or eggs from developing. Also water-resistant, fipronil is found in many monthly topical flea medications. Some dogs may have a sensitivity to the insecticide when it is applied, but this is not common.

Selamectin

Selamectin is a topical insecticide that is absorbed into the bloodstream and stops parasites in the heart, gastrointestinal tract, and the skin and hair of your dog. Flea medication with selamectin should not be used on puppies younger than six weeks old, and should be administered with caution to sick dogs or dogs with broken, irritated skin.

Citrus Extracts

Citrus extracts are a major factor in natural flea remedies due to their effects on the nervous system of insects. While they come from natural ingredients, citrus extracts can be toxic to pets, causing drooling, staggering, a drop in body temperature, skin hypersensitivity and rashes. Citrus extracts offer little advantage over other flea control medication and may not be as effective as other medications when used by themselves.

IGRs and IDIs

Insect growth regulators (IGRs) are an important ingredient in flea medication because they prevent eggs and larvae from developing, and should be used in conjunction with other ingredients that kill adult fleas. Insect development inhibitors (IDIs) also prevent juvenile fleas from developing into adults. Both IGRs and IDIs are considered extremely safe for dogs.

References

• Ingredients in flea and tick control
• Flea medication
• Common side effects of dog flea control products