DEET (N,N-diethyl-3-methylbenzamide)

General

DEET was originally patented by the US army in 1946 and became available to the public in 1957. It is known to be effective against many species of mosquitoes along with flies, chiggers, fleas, and ticks. Since its discovery no compound has been shown to be more effective. While the exact mechanism of action is unknown it is believed to interfere with insects olfactory neurons and prevent the insect from being attracted to the host.

There are many concentrations of DEET that are commercially available. The concentration of DEET is directly related to its duration of action up to 50% where it the effectiveness plateaus. Studies have shown that 5% lasts 88.4 minutes while 23.8% DEET can last for 301.5 minutes.

Pharmacology

The media has reported that the skin can absorb anywhere from 9-56% of DEET. However a 1995 study conducted by the US army using 100% DEET only showed a 5.6% absorption and a 8.4% absorption for 15% DEET in ethanol.

The DEET was absorbed through the skin in the first 2 hours of application, it is cleared from the plasma within 4 hours and completely excreted via the urine in 12 hours.

Side Effects

Most Common

Allergic Reactions-hives, contact dermatitis, anaphylaxis

Can damage plastics, rayon, spandex, leather, painted surfaces and  other synthetic fabrics. No effect on natural fibers like cotton or wool.

Severe (<50 reported cases since 1960)

Neurologically-headaches, lethargy, confusion, tremors, seizures, slurred speech and encephalopathy

Most cases of reports of side effects have occurred in young children with excessive, long term or inappropriate use. However if used as directed the risk of DEET is minimal. No correlation has been shown to exist between the concentration of DEET and the toxic effects.

Myth

No studies or case reports have revealed any link or potential for teratogenicity or oncogenicity.

How to use

DEET is available as a lotion, aerosol, spray and even impregnated in towellettes and should be applied according to the manufacturers recommendations, however a few general recommendations apply to DEET in general:

• Use sparingly

• Avoid areas around the mouth and eyes

• Avoid using on the hands of young children

• Don't apply near food or in enclosed areas

• Don't put over cuts, wounds or irritated skin

• Wash skin and clothing after returning from the outdoors

• Not recommended for use in children <2 months of age do to increased permeability of their skin