How do DEET and other repellents work?
Mosquitoes and other blood-feeding flies (such as black flies and deer flies) are attracted to hosts by skin odors and carbon dioxide from their breath. When a mosquito gets close to a host, DEET and some other repellents jam the insect's sensors and
confuse the insect so it is unable to land and bite the host successfully. Repellents are effective only at short distances from the treated surface, so the user may still see mosquitoes flying nearby. As long as the user is not getting bitten, there
is no reason to apply more DEET.
- Read and follow instructions on the label and avoid excessive use and over-application.
- For casual use by most people, a high concentration of DEET is not needed. Products with 25 percent to 35 percent DEET will provide adequate protection for adults under most conditions; use lower concentrations for children.
- To make sure you will not react to the repellent, apply the product to a small area of skin on your arm or leg before general use.
- Use just enough repellent to cover exposed skin and/or clothing.
- After returning indoors, wash treated skin with soap and water. Wash treated clothing before wearing again.
- Do not spray directly on face; spray the repellent onto hands and then apply to face.
- Avoid sensitive areas like the eyes, mouth and nasal membranes.
- Do not apply over cuts, wounds or irritated skin.
- Do not use under clothing.
- Avoid spraying on plastics (such as watch crystals and eyeglasses frames), rayon, spandex, other synthetic fabrics, leather and painted or varnished surfaces because DEET can damage those surfaces.
- Do not spray DEET- containing products in enclosed areas.
- Do not spray repellents while smoking, repellents are flammable.
- DEET products will usually repel mosquitoes for several hours, so it is not necessary to reapply the repellent more frequently than that.
- DEET products will NOT repel stinging insects such as wasps and bees.
Using DEET repellents on children?
The American Academy of Pediatrics recommends: Always follow the recommendations appearing on the product label when using repellent:
- When using repellent on a child, apply it to your own hands and then rub them on your child. Avoid children's eyes and mouth and use it sparingly around their ears.
- Do not apply repellent to children's hands. (Children may tend to put their hands in their mouths).
- Do not allow young children to apply insect repellent to themselves; have an adult do it for them.
- Keep repellents out of reach of children.
- Do not apply repellent under clothing. If repellent is applied to clothing, wash treated clothing before wearing again. (May vary by product, check label for specific instructions).
How does the percent of DEET in a product relate to the amount of protection it gives?
Based on recent studies:
- A product containing 23.8% DEET provides an average of 5 hours of protection from mosquito bites.
- A product containing 20% DEET provided almost 4 hours of protection.
- A product containing 6.65% DEET provided almost 2 hours of protection.
- A product containing 4.75% DEET and 2% soybean oil were both able to provide roughly 1 and a half-hours of protection.
What should I do if I have medical questions about DEET?
If you suspect that you or your child is reacting to an insect repellent, discontinue use, wash the treated skin and call your physician or local poison control center. If you go to a hospital or doctor, take the repellent with you.
The Florida Poison information center number:
Additional information about the active ingredients in repellents and other pesticides may be obtained from:
National Pesticide Information Center (NPIC0)
8:30 a.m. to 6:30 p.m. (central time)
seven days a week.
Or visit the National Pesticide Information Center website.
Can I use a repellent that does not contain DEET?
If you do not want to use a product containing DEET, or if your physician advises you to avoid DEET, there are other products that give you limited protection. These repellents generally use plant-based oils to repel insects. In comparison to DEET based
products, plant oil-based repellents are generally effective for a shorter time (usually less than about two hours).
Note: Vitamin B, ultrasonic devices and incense have not been shown to be effective in preventing mosquito bites.
What about treating clothes with repellents containing permethrin?
Some people use permethrin on clothing to repel ticks, mites and mosquitoes. Permethrin repellents should NEVER be applied to skin: they are to be used on clothing ONLY. Always use permethrin repellents according to the label instructions.
- When permethrin products are applied to clothing, the spray should be allowed to dry before clothing is worn.
- Permethrin works mainly by killing ticks that come in contact with treated clothes.
- Because treating clothing with permethrin is particularly effective against ticks, they reduce the risk of getting Lyme disease, Rocky Mountain spotted fever and other diseases by preventing tick bites.
- Permethrin is a pesticide and exposure should be minimized. Therefore, it should only be used when ticks or mosquitoes are numerous and other protective measures are not practical or available.
Are there other ways to help prevent insect bites?
The use of an insect repellent is not the only way to reduce the risk of bites from mosquitoes, ticks and other biting insects that may transmit disease.
Other precautions are important as well:
Avoid places and times when mosquitoes bite. Generally, the peak biting periods occur just before and after sunset and again just before dawn.