DEET is the active chemical ingredient in most insect repellents available in Canada and the United States. It is used to repel such biting pests as mosquitoes and ticks—including ticks that may carry Lyme disease.
DEET was originally developed by the U.S. Department of Agriculture in 1946 for use by the U.S. Army. DEET was registered in the U.S. for the general public to use in 1957. Today, approximately 30 percent of the U.S. population uses DEET repellents each year.
DEET disrupts the ability of biting insects to detect the source of carbon dioxide—the gas naturally given off by our skin and in our breath— which is what attracts mosquitoes and other insects to us. Insects aren’t killed—they just can’t locate their prey for a period of hours.
DEET does not kill mosquitoes; it simply repels them. According to one expert, “They go into ‘time out’ for about three hours.”
Look for repellents with no more than 30 per cent DEET for adults and no more than 10 per cent DEET for children.
Neck, wrists and ankles are important areas to apply the repellent to, and care must be taken to avoid mucous membranes (nose and eyes). When applied on the skin, the repellent effect may last from 15 minutes to 10 hours, depending on climate, the product’s composition and the type of bug you are trying to repel. When applied on clothes, the repellency effect lasts longer.
Insecticide spray cans are effective for an immediate knockdown and killing effect, but have little effect once the air has cleared. They are best used in combination with other deterrents. Mosquito nets are ideal for travelers and campers, and some types are available with insecticide in their material. Look for a mesh size of less than 1.5 mm, and repair any holes immediately.
Be sure to reapply the insect repellent if you have been swimming or perspiring, according to directions.
Use enough repellent to cover exposed skin or clothing. Don’t apply repellent to skin that is under clothing. Heavy application is not necessary to achieve protection.
Do not apply repellent to cuts, wounds, or irritated skin.
After returning indoors, wash treated skin with soap and water.
Do not spray aerosol or pump products in enclosed areas.
Do not apply aerosol or pump products directly to your face. Spray your hands and then rub them carefully over your face, avoiding eyes and mouth.
When using insect repellent on children, always apply it for them.
Always read the entire label before using.
Do not apply on irritated or sunburned skin.
Apply it only on top of clothing or to skin that is showing. Don’t use it under clothes.
Do not get it in eyes. If you do get insect repellent in your eyes, rinse with water right away.
If you are spraying, be careful not to breathe it. Always spray products in a place that is well ventilated. Don’t spray it in a tent, or near food.
Don’t spray children’s hands. They’ll be less likely to get it into their eyes or mouth.
When you don’t need the protection anymore, wash the skin with soap and water.
If you think your child is having a reaction to the product, wash the skin and get medical help right away. Take the container with you so the doctor knows what you used.
Do not use insect repellents with DEET on infants.
Although there is no known hazard to breastfed infants, nursing mothers may wish to consider DEET alternatives, such as using protective clothing and avoiding exposure to insects (see above).
Products containing citronella or lavender oil should not be used on infants.
Children aged 6 months to 2 years:
If there is a high risk of complications from insect bites (for example, an area where there are reports of West Nile virus), you can use products with DEET only once a day.
Use a product with the least available concentration: 10% DEET or less.
Although there is no known hazard to breastfed infants, nursing mothers may wish to consider DEET alternatives, such as using protective clothing and avoiding exposure to insects (see above).
Products containing citronella or lavender oil should not be used.
Use just a little bit of the product. Don’t apply it to the child’s face or hands.
It’s best not to use the product for a long time.
Use a product with no more than 10% DEET.
Do not apply more than 3 times a day.
Do not apply to the child’s face or hands.
It’s best not to use the product for a long time.
Use a product with 30% DEET or less.
If needed, re-apply when it’s no longer working. The amount of time the product protects against insect bites depends on how much DEET it has:
30% DEET provides about 6.5 hours of protection.
15% DEET provides about 5 hours of protection.
10% DEET provides about 3 hours of protection.
5% DEET provides about 2 hours of protection.
In Canada, products with a higher concentration of DEET (above 30%) are being phased out. They won’t be available after December 31, 2004. Products containing citronella and lavender oil are currently being evaluated for their safety.
Although there is no known hazard to the unborn child, pregnant women may wish to consider DEET alternatives, such as using protective clothing and avoiding exposure to insects (see above).