Permethrin is a synthetic chemical used as an insect repellent and insecticide. It is effective against a variety of pests, including mosquitoes, ticks, and fleas. Often found in sprays, lotions, and treated clothing, permethrin works by disrupting the nervous system of insects, leading to their death. This compound is commonly used in public health to control the spread of diseases like West Nile virus and Lyme disease. It is generally considered safe for humans and pets when used as directed, but it is important to follow application guidelines to minimize any potential risks.