What is the primary active ingredient in many mosquito repellents?

The primary active ingredient in many mosquito repellents is DEET (N,N-Diethyl-meta-toluamide). DEET has been widely used since it was developed by the U.S. Army in the 1940s as a repellent against mosquitoes and other biting insects. Its effectiveness is well-documented, making it one of the most common and trusted active ingredients in commercial insect repellents.

DEET works by interfering with the mosquitoes' ability to sense human presence, essentially masking the scent that attracts them. It tends to have a long-lasting effect, providing protection for several hours after application, which is particularly valuable during outdoor activities where exposure to mosquitoes is a risk.

While other options such as permethrin, picaridin, and citronella oil are also used in insect repellent products, they have different properties and mechanisms of action. Permethrin is a pesticide primarily used on clothing and gear rather than directly on the skin, picaridin is an effective alternative that is sometimes preferred for its lesser odor, and citronella oil is a natural repellent with variable effectiveness. However, DEET remains the most prevalent and effective ingredient for repelling mosquitoes in many formulations.