Insect Precautions

Insect Precautions — Permethrin, Deet, and Picaridin

What is Permethrin?

Permethrin is a synthetic form of the naturally occurring insecticide, pyrethrum, which comes from Chrysanthemums. Permethrin is used in varying concentrations for agricultural use, treatment of head and body lice on humans, and as an insect repellent. It is repellent to mosquitos, ticks and other insects. Permethrin, when used as an insect repellent, is used on clothing only, not on skin.

Is Permethrin effective as an insect repellent?

YES! Permethrin is an important part of a safe and effective mosquito prevention program. Tests on mosquitoes conducted by the military show that when lightweight uniforms were treated until moist (approximately 4 ½ oz), Permethrin (0.5%) gave 97.7% protection from mosquito bites. Even greater protection was obtained by combining Permethrin applied to clothing with a DEET-based repellent (20-35%) applied to the skin.

Why is Permethrin put on clothing and bed nets?

This product was developed especially for application to clothing. Permethrin bonds to clothing where it remains repellent to insects. Reports vary as to how long treated clothes remain repellent –2 weeks to 6 months (5-20 detergent washings).

Is Permethrin safe?

A temporary, mild skin irritation has been reported in a small number of cases. No serious or long lasting effects have been reported from the use of Permethrin. In the environment, Permethrin readily bonds to soil (and clothing) where it is biodegradable in 1-16 weeks. Permethrin has a low level of toxicity to birds and mammals, but it is highly toxic to insects, bees and fish. For this reason, it is important that residual material does not contaminate blooming crops, waterways or other aquatic areas.

How do I apply Permethrin?

  • One can of Permethrin will treat several outfits – shirts, shorts, and socks.
  • Spread out all of the clothes to be treated on a flat surface. Hold the can approximately 12inches away from the clothing. Spray the clothing using sweeping motions until the clothing is moist. Pay close attention to cuffs and collars. Turn the clothes over and repeat the process. Hang up the clothes and allow them to dry thoroughly.
  • Repellent properties will last longer if clothes are sealed in a resealable plastic bag until use.
  • Treat mosquito nets in the same manner as above.

Should I use insect repellant as well as Permethrin?

Yes. Insect repellents containing DEET (N,N –diethyl-meta tolumide) or picaridin, should be used on exposed skin and Permethrin repellents should be used on clothes. The importance of avoiding mosquito bites to avoid mosquito borne illnesses cannot be overemphasized.

Is DEET safe?

The toxicity of DEET is unclear and is still under investigation. It is known that DEET is absorbed by the skin and excreted by the kidneys. It is thought that children absorb more DEET than adults because of the larger skin to body weight ratio.

To minimize DEET absorption, the following precautions are suggested:

  • Apply DEET only as frequently as the manufacturer’s recommendation.
  • Avoid applying repellents to children’s hands that are likely to have contact with the eyes or mouth.
  • Do not drink repellents or get them into the eyes or mouth. Drinking large amounts of DEET can be fatal. Avoid inhaling DEET spray.
  • Keep repellents out of open cuts or inflamed or irritated skin.
  • Wash off repellents after coming indoors.
  • Keep DEET out of the reach of children and make sure that DEET is applied by adults or older teens.

What DEET concentration should be used?

DEET repellents are available in concentrations from 5% to 100%. The higher the concentration of DEET, the longer it repels insects (30% DEET repellents give 4–6 hours of protection).


The Student Health Center Travel Clinic recommends 20–35% DEET to achieve a balance between convenience, protection, and safety.


DEET with Polymer treatment allows a lower concentration of DEET to last longer. Some brand names of DEET plus polymer are “Ultrathon,” “Hourguard,” and “Skedaddle.”


Studies have shown that Picaridin is effective, safe and has fewer unpleasant qualities than DEET. Picaridin is odorless, does not melt plastics, or feel oily on skin. Studies show that Picaridin is as effective as DEET when used at the same strength. Picaridin is available in brands such as Cutter and AVON.

All of these products are available over the counter at retail and sporting goods stores, pharmacies and on-line.

Always follow package instructions.

What other methods help prevent insect bites?

  • Use unscented soaps and avoid perfume.
  • Wear socks and shoes and long pants when outdoors. Most Malaria mosquitoes fly near theground.
  • Dress in light colors.
  • Use lightweight, loose fitting clothes that cover much of the body.
  • Make sure that your sleeping area is insect free--use air conditioning, good window screens or bed nets. Check your room or bed net each night to make sure no mosquitoes have entered.
  • Pack duct tape so you can use it to patch window screens or cracks between window and walls.
  • Stay indoors during the evening and night as much as possible.
  • Check yourself and your children for ticks every day.
  • Avoid leaving clothes on the ground or floor.
  • Choose an upper floor in a hotel if possible.
  • Use fans when available. Air currents help keep mosquitoes away.

Where can I buy these products?

Many stores carry these products like camping and sporting stores/departments. They are also available at the Student Health Center Pharmacy and on the internet.


Planning a trip abroad?

Make time for an appointment at the Student Health Center Travel Clinic.