DEET, known chemically as N,N-diethyl-meta-toluamide, is a widely recognized and effective chemical compound used as an insect repellent. It is commonly found in various repellent products and has been utilized for over 60 years by millions globally to deter mosquitoes, ticks, fleas, and biting flies. Its widespread application plays a role in preventing insect-borne diseases like West Nile virus, Lyme disease, dengue fever, and malaria.
The DEET Molecule Explained
DEET’s full chemical name is N,N-Diethyl-meta-toluamide, with the chemical formula C12H17NO. It is a synthetic, man-made compound. The molecular structure of DEET features a toluene ring substituted with an ethyl group and an N,N-diethyl amide functional group.
DEET is a clear, colorless, or faintly yellow liquid with a distinct, faint odor. It has low solubility in water but dissolves readily in most organic solvents. The U.S. Army developed the compound in 1946 for soldier protection in insect-infested regions. It became available for civilian use in 1957 and has been commercially marketed as a personal insect repellent since 1965.
How DEET Repels Insects
DEET repels insects by interfering with their sensory systems, particularly their ability to detect hosts. It does not kill insects but confuses their olfactory (smell) receptors.
Research suggests DEET directly interacts with insect odorant receptors, blocking responses to attractive odors. Some hypotheses propose DEET either activates an innate avoidance circuit in the insect’s olfactory system or cooperates with host odors to create a repellent effect, making users less detectable.
For example, in mosquitoes, DEET can reduce the sensitivity of olfactory receptor neurons to human odors such as lactic acid and carbon dioxide. While insects may still land on treated skin, DEET works on contact to prevent them from biting.
Using DEET Safely and Effectively
When using DEET products, follow label directions for safe and effective application. Product concentration affects protection duration; higher concentrations generally offer longer effects. However, concentrations above 50% do not provide additional protection and may increase skin irritation. For most situations, 10% to 25% DEET products are adequate, offering several hours of protection.
Apply just enough DEET to cover exposed skin or clothing in a thin, even layer. Avoid applying it to cuts, wounds, irritated skin, or areas around the eyes and mouth. If using a spray, apply it onto your hands first, then to the skin, especially for children. After returning indoors, wash treated skin with soap and water.
For children, repellents with up to 30% DEET are generally considered safe for those over two months old. Always supervise children during application and avoid applying it to their hands or fingers, as they may put their hands in their mouths.
Pregnant and lactating individuals can generally use DEET as recommended, as there is no evidence suggesting it poses a health hazard to unborn babies or breast-feeding children when used appropriately. Skin and eye irritation are the most frequently reported side effects, but serious reactions are rare and often linked to misuse, such as swallowing the product or applying it to broken skin. DEET can also damage certain synthetic fabrics, plastics, and painted surfaces.