DEET

DEET, short for N,N-diethyl-meta-toluamide, is a common active ingredient in insect repellents used to deter biting insects such as mosquitoes and ticks. It is applied to skin or clothing and comes in formulations including liquids, lotions, sprays, and wipes. The exact mechanism by which DEET prevents bites is not fully understood, but it is believed to interfere with the insects’ ability to detect host odors.

Developed by the U.S. Army in 1946 for protection in jungle environments, DEET was first marketed to consumers in 1957. In the United States, DEET products are regulated by the Environmental Protection Agency and require labeling with usage instructions and safety warnings. Formulations range from about 5% to 100% DEET, with higher concentrations generally offering longer duration of protection but not necessarily greater repellency.

DEET is generally considered safe when used as directed. Side effects are typically mild, such as skin irritation or rash. Rare but serious adverse events have been reported following excessive application or ingestion, especially in children. Guidance for use in children varies; authorities commonly advise that DEET can be used on children older than two months, with concentrations not exceeding 30%, and that it should be applied to exposed skin or clothing while avoiding hands, eyes, mouth, and irritated skin. After outdoor exposure, it should be washed off. If mixing with sunscreen, sunscreen should be applied first and allowed to dry before applying DEET.

Environmental considerations include potential effects on aquatic life and non-target organisms at high concentrations; DEET degrades over time but can persist in water under certain conditions.