DEET

Products

DEET is most commonly used in the form of a spray, but is also sold in other dosage forms. Among the best-known products in many countries is Anti Brumm forte. Some products are combined with other repellents. DEET was developed by the United States Department of Agriculture for the military in the 1940s and marketed for civilian use beginning in 1956. Anti-Brumm was invented in the 1970s by Eduard Vogt of Herrliberg, Switzerland.

Structure and properties

DEET (C12H17NO, Mr = 191.27 g/mol) is a methylated and nitrogen ethylated benzamide and is known as ,-diethyl-3-methylbenzamide or ,-diethyl–toluamide. DEET is an odorless to faintly odorous, colorless to faintly yellow, lipophilic oily liquid that is virtually insoluble in water. DEET is manufactured synthetically but also occurs naturally in certain insects.

Effects

DEET is insect repellent by forming a protective scent coat on the skin. It has a good protective effect against mosquitoes, mosquitoes, ticks, horseflies, mites, lice, tsetse flies and other flies. On the other hand, it is ineffective against bees, bumblebees, wasps and hornets. Its effectiveness has been proven in clinical studies. DEET is among the most effective repellents and is considered the gold standard. The duration of action depends on the concentration of the formulation and is up to 8 hours against mosquitoes (up to 12 hours according to the manufacturer) and 2 to 4 hours against ticks. Concentrations are 20 to a maximum of 30% in many countries, and over 90% in some products in other countries (e.g. OFF!). So the application should be repeated in time.

Mechanism of action

Two different hypotheses are available on the mechanism of action based on experiments. Either the insects are repelled directly by the smell of the substance or DEET reduces sensitivity to endogenous substances that attract insects (e.g., lactic acid), thus creating a kind of “stealth”. The insects can no longer smell people and therefore do not bite them.

Indications

For the prevention of insect bites by mosquitoes, flies, horseflies, fleas or ticks and as a tropicalized repellent for malaria prophylaxis.

Dosage

According to the directions for use. DEET is sprayed on the skin or on textiles such as cotton and wool.

  • Apply evenly and without gaps.
  • For children, apply sparingly and avoid the hands and mouth area.
  • Omit face or apply with caution, do not get in eyes, do not apply to mucous membranes or damaged skin.
  • Repeat application in a timely manner.
  • Apply no earlier than 20 minutes after applying the sunscreen.
  • When the protection is no longer needed, wash the skin areas with soap and water.
  • DEET attacks certain plastics, such as clothing and watches.

Contraindications

DEET should not be used in cases of hypersensitivity, in infants and young children, during pregnancy and lactation. It should not get into the eyes, on injured or diseased skin areas, wounds or on mucous membranes, should not be sprayed directly into the face and should not be applied when there is an increased tendency to convulsions. The products should be kept away from children because they are toxic if ingested accidentally. There is no consistent information as to when DEET should be used in children. In our view, it should not be used in children under 3 years of age. DEET is probably not teratogenic, but should not be used by pregnant women as a precaution.

Adverse effects

DEET is generally considered well tolerated and is used by many millions of consumers each year. Rare possible adverse effects include local skin and mucous membrane reactions, skin irritation, allergic contact dermatitis, skin blisters, itching, and angioedema. Accidental spraying into the eyes may irritate and damage the conjunctiva. Neuro- and cardiotoxicity from external use is controversial. In very rare cases, encephalopathies, seizures, coma, low blood pressure, bradycardia and death have been reported. DEET is absorbed through the skin, metabolized in the liver, and excreted. Children are generally considered to be more susceptible to adverse effects; however, this is not certain and adults may also experience severe side effects.Accidental ingestion may cause nausea and vomiting, indigestion, low blood pressure, agitation, tremors, convulsions, coma and death. DEET attacks and can damage certain plastics and paints. These include vinyl, spandex, rayon, acetates and certain leathers.