Hartz and Frontline flea drops are two of among many options available for treating fleas on a dog or cat. Understanding the difference between these flea preventatives is vitally important. Both are capable of causing harm when used improperly.
The two primary active ingredients in Hartz flea drops are 3.6 percent (S)-methoprene and 40 percent Etofenprox.
The two primary active ingredients in Frontline flea drops are 11.8 percent (S)-methoprene and 9.8 percent Fipronil.
Pyrethrins and Pyrethroids
Flea-drop products contain pyrethrins and pyrethroids, which are insecticidal components, both natural and synthetic, that are used to kill and repel insects.
Both Hartz and Frontline flea drops are harmful to humans, dogs and cats if swallowed. Hartz flea drops have been known to cause allergic reactions and other skin reactions in some animals.
Hartz flea drops are applied to the back of the neck and meant to kill fleas on the surface of the skin. Frontline flea drops are applied in the same manner, but are meant to be absorbed into the sebaceous glands, where they can be released consistently over the period of 30 days from the hair glands in order to provide continued protection.