Chemical controls Listed by the Washington Toxics Coalition as the safest chemicals available for killing fleas, Safer, Inc. products are relatively non-toxic to pets. There are many pyrethrum-based products available, but cat owners should be aware that some cats are sensitive to pyrethrum. Another safe and natural pesticide is linalool, a chemical derived from citrus oils that is toxic to adult fleas. Recent studies indicate that limonene, a related citrus derivative, may cause tumors in rats. Until limonene is known to be safe for use around other animals, choose shampoos, sprays, and other treatments that contain only linalool.
Many products control fleas in all stages of their life cycle.
Methoprene, a growth regulator that targets immature fleas, does not kill adults but can be effectively and safely combined with other chemicals such as pyrethrum. Beware of mixtures with more toxic insecticides, and use only if other control methods fail over time. Another option is to use products that kill fleas by drying them out rather than poisoning them. Diatomaceous earth, a fine mineral powder, or boric acid, a moderately toxic chemical, can both be applied to carpets and floors to desiccate fleas, but can pose risks to humans. A safer alternative for rug treatment is Borax, sold in the laundry detergent section of the grocery store.