• James Tippett MD

What's in Insect Repellant?

Updated: Aug 8, 2018

Protecting yourself from insect bites is very important! In addition to being itchy and uncomfortable, their bites can spread diseases like Lyme (ticks) and West Nile or Zinka viruses (mosquitoes). Of course, there are other biting bugs that don’t transmit serious disease, but certainly can spoil an otherwise enjoyable day outdoors. Examples include chiggers, fire ants, horse flies, and those almost invisible biting gnats known as “no-see-ums”.

An insect repellent (sometimes called bug spray) is a substance applied to clothing, skin, or other surfaces, that repels insects and discourages them from landing or crawling on that surface. Some repellents are insecticidal (bug killers) but most just ward off the critters.

There are a number of synthetic (made in the laboratory) repellents and natural repellents that are variably effective. There are pros and cons to each of them. Synthetic repellants are typically superior and/or last longer than natural products. However, some people seem to have “chemophobia” and unfounded concern about using the synthetic repellents. This has resulted in the development of a multitude of “natural” or “chemical-free” repellants with a variety of active ingredients, most commonly derived from plant oils. Again, their effectiveness tends to be inferior and their duration of protection short because of evaporation, and thus frequent applications are required.

There is a misconception that insects are repelled by the odor of the product. This is not true, so using an odorless repellent does not compromise its effectiveness. However, a scented natural product may be chosen if one desires to smell like a ‘florist showroom’.

The guys in your golf group will not likely be impressed!

There is very good clinical evidence that the two most effective repellents that can be applied to the skin are DEET (diethyltoluide) and picardin (also called icardin and brand name Saltidin). Then, there is permethrin (brand name Nix, among others), a chemical that when sprayed on clothing or other fabric kills bugs (insecticidal) when they come into contact with the treated fabric.

DEET is the most widely used repellent and has been thoroughly studied and used for over 70 years. It was developed for the US Army in the 1940’s as a repellent for soldiers involved in jungle warfare. It provides protection from almost all biting insects. Products are available that contain varying amounts of DEET from 4% to 100%. Its effectiveness increases with increasing concentrations, but peaks at 30%. Concentrations above 30% do not improve protection but they do last longer. A 30 % product last about 8 hours, so using higher concentrations is not particularly beneficial. Also, higher concentrations are more expensive, very oily, and have an unpleasant smell. Concentrations of 30 % are safe for children over 2 months old, as well as pregnant and lactating females.

A negative for using DEET is that it is a plasticizer. That is, it can damage plastics, leather, vinyl, and other synthetic materials. Hands must be washed thoroughly with soap and water after its use or there is risk of damaging such things as eyeglass frames, auto paint, nail polish, and perhaps most importantly, golf club grips! Otherwise, after all of these years, there is no scientific evidence that DEET contaminates or harms the environment.

Picardin is also a synthetic repellent made in the laboratory using a product from the black pepper plant as a template. Some research has shown that it is comparable in effectiveness to DEET but only at concentrations of at least 20 %. Other studies have reported that it is less effective and shorter acting. It does have advantages of being less oily or sticky, is odorless, and does not damage other materials or surfaces. It may be preferred in people with sensitive skin and seems to repel horse flies better. It, like DEET, is safe in children over 2 months old and in pregnant or lactating females.

Permethrin is synthesized using a product from the chrysanthemum plant as a template. Sprayed on clothing, it kills biting insects, particularly ticks and mosquitoes. After spraying and drying, the impregnated clothing can remain protective after a number of washings. It is not effective on skin due to rapid evaporation from body heat.

In summary, to obtain the maximum protection from biting insects, spray clothing with permethrin and apply a repellent product to exposed skin with either 30% DEET or 20% picardin. Applying these products on skin underneath clothing is not beneficial.

We hope that you can use this article as a reference to help you read labels and assist you in obtaining the best insect repellent for your needs and

“Take the Sting Out of those Biting Things”

Dr. Tippett is the founder of CQHP, Inc. located at 1210 Commerce Dr. Suite 106, Greensboro, Ga. 30642. He can be reached at 706-510-3659. Visit his webpage at

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