Permethrin as a Defense Again Tick Bites: What You Should Know
Spring and summer marks the peak of tick activity and three human-biting species are active right now in our area:
- Deer Ticks – Can cause: Lyme disease, babesiosis, anaplasmosis, Powassan virus, borrelia miyamotoi
- Lone Star Ticks – Can cause: Ehrlichiosis, tularemia, and increasing cases of Alpha-Gal Syndrome (the red meat allergy)
- Dog Ticks – Can cause: Rocky Mountain spotted fever and tularemia
These diseases can vary in severity, and some may cause long-term or chronic health issues.
There are many effective prevention strategies available in full on our website, but today, we’re highlighting one of the most powerful tools available: Permethrin-treated clothing.
What Is Permethrin?
Permethrin is a synthetic insecticide in the pyrethroid family, modeled after natural extracts from chrysanthemum flowers. It was first registered with the U.S. EPA in 1979, re-registered in 2006, and is also FDA-approved for medical use in lice and scabies treatments.
It’s commonly found in:
- Flea and tick collars for dogs
- Cattle ear tags
- Head lice and scabies treatments
- Insect-repellent sprays for clothing
How Does Permethrin Work?
Permethrin affects the nervous systems of insects, causing paralysis and death upon contact. Unlike ticks, humans and dogs metabolize permethrin quickly, making it safe for external use on clothes and, when prescribed, topical creams.
- Less than 1% is absorbed through human skin
- The small amount that is absorbed is typically eliminated in urine within five days
- Permethrin is 2,250 times more toxic to ticks than humans
Is Permethrin-Treated Clothing Safe for Humans?
Yes. When the U.S. military began using permethrin-treated uniforms in 1993, a consortium of external experts including the National Research Council and Committee on Toxicology conducted a comprehensive study and found no significant health risks with long-term use.
The EPA conducted a follow up assessment in 2009 looking at multiple exposure scenarios for permethrin factory-treated clothing, including toddlers wearing or mouthing the clothing, and military personnel who wear permethrin-treated uniforms on a daily basis. All exposure scenarios showed that permethrin factory-treated clothing is unlikely to pose any significant immediate or long-term hazard to people wearing the clothing.
Permethrin-treated clothing is recommended and endorsed by the CDC, EPA, Department of Defense, World Health Organization, European CDC, National Institute for Occupational Safety and Health, and National Pest Management Association.
There is no age restrictions on using permethrin-treated clothing. There is also no evidence of reproductive or developmental effects to mother or child following use during pregnancy or nursing.
Does Permethrin Cause Cancer?
- The International Agency for Research on Cancer (IARC) classifies permethrin as “not classifiable” regarding human carcinogenicity.
- The U.S. EPA considers permethrin potentially carcinogenic when ingested in large amounts (based on mouse studies), but no human studies have shown cancer risks from treated clothing or prescribed topical treatments.
- The military has been treating uniforms with Permethrin since 1993 to protect soldiers from tick and mosquito-transmitted diseases. Even with long-term exposure, there were no adverse effects shown.
How to Use Permethrin Safely
- You can either purchase pre-treated clothing or treat your own clothes with permethrin purchased from stores. Pre-treated clothing (or clothing you sent in to be treated) lasts about 70 washes. DIY treated clothes last about 6 washes or 6 weeks, whichever elapses sooner.
- Permethrin sprays purchased in stores should only be applied to clothing, gear, and inanimate objects.
- Spray garments while off your body
- Keep away from pets and children during application. Wet permethrin is highly toxic to cats because they lack the liver enzyme to break it down.
- Follow all label instructions
- Allow clothing to dry before wearing
- Re-treat as recommended by the product
- Wash treated clothes separately
- Combine with other methods like tick checks, long sleeves, showering after outdoor activity, and EPA-registered repellents on exposed skin
Final Tips for Tick Season
✔ Wear permethrin-treated clothing
✔ Do regular tick checks after being outdoors
✔ Shower after outdoor activities
✔ Visit our website for prevention guides and up-to-date tick information
Additional Resources
Barnstable County’s Tick-Borne Illness Information & Prevention Page:
Visit our Tick-borne Illness and Prevention Page >>>
Permethrin Treated Clothing – Tickology:
Insect Shield:
