Pesticides that are effective against bed bugs include cold-pressed neem oil, chlorfenapyr, and pyrethroid-type insecticides such as allethrin. All of these insecticides work in slightly different ways and present different levels of hazard to humans and companion animals.
The most common insecticides used against bedbugs contain either pyrethroid or pyrethrins, two closely related classes of chemical. Pyrethrins are derived from chrysanthemums, while pyrethroids are synthetics that behave similarly. Allethrin was the first pyrethroid synthesized and, as of 2015, is still in common use against bedbugs.
Chlorfenapyr is a newer, slow-acting chemical that can help prevent fresh re-infestations.
Neem oil is the least toxic bedbug insecticide for humans and pets, although it is mildly irritating to the skin. Pesticides containing allethrin can cause itching, burning, and nausea, while chlorfenapyr is considered acutely toxic and a possible carcinogen by the Environmental Protection Agency.