From the Guidelines
Permethrin and DEET are both effective insect repellents, but permethrin-treated clothing plus DEET on exposed skin provides the most comprehensive protection against ticks and other disease-carrying insects. Permethrin is applied to clothing and gear rather than skin, providing protection for up to 6 weeks or through multiple washings, and it actually kills insects on contact rather than just repelling them 1. DEET, on the other hand, is applied directly to skin and provides immediate protection for 2-8 hours depending on concentration (10-30% is typically recommended), and it primarily works by creating a vapor barrier that confuses insects' ability to detect humans 1.
Some key points to consider when using permethrin and DEET include:
- Permethrin should not be applied to skin, as it is inactivated by skin lipids, and should be applied to outer clothing, such as shirts and pants, according to label directions in a well-ventilated area 1.
- DEET concentrations as low as 10% and those containing 25%--35% concentrations are considered optimal, and concentrations >50% do not confer additional protection 1.
- The American Academy of Pediatrics has recommended that DEET concentrations no greater than 20%--30% should be used for children 1.
- Permethrin-impregnated clothing can reduce tick bites by >80% among outdoor workers, and the use of DEET and permethrin should be considered by persons who enter heavily infested tick habitats where the risk for being bitten is high and the potential for tick-borne disease infection exists 1.
Overall, the combination of permethrin-treated clothing and DEET on exposed skin provides the most effective protection against ticks and other disease-carrying insects, and this approach is recommended for individuals who spend time outdoors in high-risk areas 1.
From the Research
Comparison of Permethrin and DEET as Insect Repellents
- Permethrin is applied to clothing rather than to skin and is a better repellent against ticks than DEET 2.
- DEET has remained the most effective repellent against mosquitoes, biting fleas, gnats, and chiggers since its introduction in 1956 2.
- The combination of topical chemical repellents, such as DEET or picaridin, and permethrin-impregnated clothing provides better, longer-lasting protection against malaria-transmitting mosquitoes and ticks than topical DEET or picaridin alone 3.
Effectiveness of Permethrin-Treated Clothing
- Permethrin-treated clothing is effective against susceptible mosquito populations but not against permethrin-resistant populations 4.
- The protective effect of permethrin-treated clothing against mosquitoes is impacted by factors such as wash frequency, fabric type, and the susceptibility/resistance status of local mosquito populations 4.
- Permethrin-impregnated clothing provided 34% protection against tsetse flies when worn alone, but combining it with DEET repellent on exposed skin increased protection to 91% 5.
Synergistic Effects of Permethrin and DEET
- Combining permethrin and DEET on bed nets using a novel long-lasting polymer-coating multi-layer technique resulted in synergistic insecticidal and repellent effects 6.
- DEET reduced the concentration-dependent permethrin 100% knockdown time and 100% kill time, and increased spatial and excitatory repellency, resulting in enhanced biting protection 6.
- The combination of permethrin and DEET on bed nets provided 100% biting and probing protection for up to 83 weeks, depending on the concentration of the active ingredients 6.