Safe for people and pets, Natural Chemistry De-Flea Shampoo Concentrate kills fleas on contact without the use of pyrethrin based pesticides. Also effective on ticks and lice. Parasites do not become resistant, so the product never loses its effectiveness. Will not wash out spot-on flea and tick control products. De Flea can even be used on very young puppies and kittens, nursing mothers, and when other flea control products are present. The active ingredients in Natural Chemistry De-Flea Shampoo Concentrate work together to soften the waxy exoskeleton of fleas, ticks, lice, mites, and other insects. Once the insect's armor has been penetrated, its internal organs are saturated and the insect quickly bursts. De Flea products work for all stages of an insect's life cycle, eggs, larvae, pupae and adult--effectively eliminating all insects from the home.