Does Permethrin Wash Out of Clothes? How Long Protection Lasts
Permethrin-treated clothing helps reduce tick exposure
Washing and wear reduce effectiveness over time
Protection may continue after multiple washes
Many people ask whether washing reduces the effectiveness of permethrin-treated clothing.
For people trying to prevent tick bites, the answer matters. Clothing treatment is often recommended as one layer of protection, but durability after repeated washing remains an important question.
Repeated washing reduces permethrin levels, but studies suggest treated clothing may still provide protection after multiple wash cycles. In one study, effectiveness declined after repeated wear and washing, yet treated clothing remained more protective than untreated garments.
A study by Connally and colleagues examined whether repeated wear and machine washing changed the ability of permethrin-treated clothing to repel or kill ticks.
Quick Answer: Does Permethrin Wash Out of Clothes?
Yes. Repeated washing lowers permethrin concentration. However, protection may continue after multiple wash cycles, although effectiveness gradually declines over time.
How Researchers Tested Permethrin-Treated Clothing
Investigators evaluated treated clothing after wear and repeated machine washing and drying cycles.
Blacklegged tick nymphs were forced into contact with permethrin-treated clothing for 30 to 120 seconds before investigators monitored tick behavior.
The goal was to determine whether washing reduced contact irritancy and toxicity against Ixodes scapularis nymphs.
How Effective Is Permethrin Before Washing?
Researchers found the strongest effect before clothing had been washed.
Connally reported that “pristine permethrin-treated clothing displayed strong contact irritancy and toxicity” toward tick nymphs.
One hour after exposure to untreated versus treated textiles, only 0% to 30% of ticks exposed to freshly treated clothing demonstrated normal movement.
These findings suggest freshly treated clothing may significantly impair tick movement after contact.
Does Permethrin Wash Out of Clothes?
Repeated washing reduced the concentration of permethrin substantially.
After 16 days of wear and 16 machine wash-and-dry cycles, investigators reported a 50% to 90% reduction in permethrin concentration.
This reduction was associated with lower toxicity and less contact irritancy against ticks.
After repeated wear and washing, 31% to 67% of ticks exposed to treated textiles still demonstrated normal movement after one hour.
Even with reduced effectiveness, treated clothing continued to outperform untreated garments.
For untreated clothing, 90% to 100% of ticks continued moving normally after contact.
How Long Does Permethrin Last on Clothes?
The study suggests protection decreases over time rather than disappearing completely.
Factors affecting durability may include:
- Number of wash cycles
- Type of textile fibers
- Amount of wear
- Drying methods
- Initial treatment concentration
Protection appears strongest before repeated washing but may persist even after multiple laundering cycles.
What About Permethrin-Treated Socks and Shoes?
Treated socks appeared less effective than other treated clothing.
Researchers speculated that looser textile weave patterns may reduce contact between ticks and treated fibers.
They also suggested some fabrics may retain less permethrin.
Treated shoes that were worn but not repeatedly washed continued demonstrating toxic effects against ticks.
Study Limitations
The findings should be interpreted cautiously.
Ticks may reach exposed skin in less than 30 seconds, potentially reducing the benefit of contact toxicity.
The study also did not evaluate situations where ticks bypass treated clothing and crawl directly onto exposed skin.
Finally, investigators did not address questions some parents raise regarding insecticide exposure from treated textiles.
Additional prevention strategies remain important. Learn more about Lyme disease prevention.
Frequently Asked Questions
Does permethrin wash out of clothes?
Yes. Repeated washing reduces permethrin concentration, though treated clothing may continue providing some protection after multiple wash cycles.
How long does permethrin last on clothes?
Protection gradually declines over time and repeated washing, but effectiveness may persist after many laundering cycles.
How many washes does permethrin last?
This study evaluated clothing after 16 wear-and-wash cycles and found reduced—but still measurable—protective effects.
Are permethrin-treated clothes still helpful after washing?
Yes. Researchers found washed treated clothing remained more protective than untreated garments.
Should treated clothing be the only prevention strategy?
No. Tick avoidance, body checks, and additional prevention measures remain important.
Clinical Takeaway
Permethrin-treated clothing appears most effective before repeated washing, but protection may continue even after multiple wash cycles.
Clothing treatment should be viewed as one component of a broader tick bite prevention strategy.
Repeated washing reduces effectiveness, but treated clothing still appears more protective than untreated garments.
Related Articles
These related articles explore tick prevention, protective clothing, and strategies to reduce tick exposure.
Permethrin-Treated Clothing and the Hot Foot Effect
How to Kill a Tick on Your Clothes
DEET for Tick Prevention
Bad Signs After a Tick Bite
Is It Too Late to Treat a Tick Bite?
References
- Prose R, Breuner NE, Johnson TL, Eisen RJ, Eisen L. Contact Irritancy and Toxicity of Permethrin-Treated Clothing for Ixodes scapularis, Amblyomma americanum, and Dermacentor variabilis Ticks. J Med Entomol. 2018;55(5).
- Connally NP, Rose DA, Breuner NE, et al. Impact of Wearing and Washing/Drying of Permethrin-Treated Clothing on Their Contact Irritancy and Toxicity for Nymphal Ixodes scapularis Ticks. J Med Entomol. 2018.
Dr. Daniel Cameron, MD, MPH
Lyme disease clinician with over 30 years of experience and past president of ILADS.
Symptoms • Testing • Coinfections • Recovery • Pediatric • Prevention
I live in SE Pa, my dear daughter has had Lyme disease with bullseye rash and other symptoms twice, and once with Neuroborreliosis symptoms and highly positive 2 tier serology and Western blot for IgM and IgG. She has never recovered fully from her 3rd bout. I urge everyone in highly endemic areas like mine to wear permethrin treated clothing, though it may not work 100% and though I, too, do not like the idea of wearing pesticides- the alternative of Lyme or other tick-borne disease is worse. I watched a deer tick struggle and die on my permethrin treated socks while gardening and it was very satisfying.