Permethrin for ticks: the complete field guide
The single most effective thing you can do to keep ticks off — and it doesn't go on your skin. Here's everything we've learned treating our own clothing for four seasons in Lyme country.
- Permethrin treats clothing and gear, never skin — pair it with picaridin or DEET on exposed skin.
- It kills ticks on contact with the fabric, usually before they reach you. The CDC recommends it for tick country.
- A DIY spray lasts ~6 weeks or 6 washes; factory-treated gear lasts ~70 washes.
- Wet permethrin is toxic to cats — treat outdoors, dry fully, then it's inert and safe.
If you spend time in tall grass, leaf litter, or the woods anywhere ticks live, permethrin is the highest-leverage protection there is — and it's the piece most people skip because it works differently from everything else in the repellent aisle. It's not a lotion you rub on. It's a treatment you apply to your clothes, days before you head out, and then largely forget about.
This is the hub of our permethrin series. Below is the whole picture — what it is, how it works, how to apply it, how long it lasts, and how to use it safely — with links out to the deep-dive guides on each piece.
What permethrin actually is
Permethrin is a synthetic version of a compound found in chrysanthemum flowers (a "pyrethroid"). For decades it's been used on livestock, in agriculture, and in medical lice and scabies treatments. In the tick world, it's registered by the EPA as a fabric treatment: you apply a 0.5% spray to clothing, let it bond to the fibers as it dries, and it stays active through repeated wear and washing.
What makes it different from picaridin or DEET is the mechanism. Those are repellents you wear on skin — they make you a less appealing target. Permethrin is an insecticide that lives on your clothing.
Does it repel ticks, or kill them?
This is the most misunderstood thing about permethrin, so it's worth being precise: it mostly kills. A tick that climbs onto treated fabric picks up a dose through its legs that quickly disorients it — the classic "hot-foot" effect — and it drops off or dies before it can crawl to skin and bite. There's a modest repellent effect too, but the reason entomologists rely on it is that treated clothing is actively lethal to ticks on contact, not merely off-putting.
That's also why it pairs so well with a skin repellent. Permethrin handles the ticks that land on your clothes (most of them, since ticks usually climb up from grass and leaf litter); picaridin or DEET covers the exposed skin at your ankles, neck, and wrists.
The two-layer strategy
The approach we (and most tick researchers) actually use: permethrin on clothing + picaridin or DEET on skin. Neither layer alone is as good as both together. See our tested picks for each layer.
How you apply it
Treating clothing is simple but there's a right way to get even, durable coverage — spray outdoors, saturate the fabric to slightly damp, and let it dry for two to four hours before wearing. Focus on the fabric that ticks contact first: pant legs, socks, cuffs, and the lower shirt.
We wrote a full step-by-step with photos:
Guide How to apply permethrin to clothing → Coverage, drying time, what to treat first, and the mistakes that waste half the bottle.How long it lasts
Permethrin's lifespan is measured in wash cycles, not hours. A do-it-yourself spray like Sawyer's is rated for roughly 6 weeks or 6 washes. Factory-treated garments — where permethrin is bonded to the fibers under controlled conditions (Insect Shield is the best-known) — hold up for around 70 washes, essentially the usable life of the garment. How you launder matters: gentle, cold, line-dry stretches it; hot water and heavy detergent shorten it.
Not sure when your treated clothes — or your skin repellent — are due for a refresh? Our calculator does the math:
Free tool Repellent duration calculator → Estimate protection time and re-treatment timing for permethrin, picaridin, DEET and more.Is it safe? Kids, pregnancy, and pets
Used as directed, permethrin has a long safety record. The key facts:
- People: once treated clothing is dry, the permethrin is bonded to the fabric and exposure to your skin is minimal. Treated clothing is widely used on children and is considered safe when dry.
- Cats: this is the one hard rule. Wet permethrin is highly toxic to cats — they can't metabolize it the way other mammals do. Treat clothing outdoors, keep cats away until it's completely dry, and it becomes inert.
- Dogs: safe — permethrin is even an active ingredient in some dog tick-and-flea products (never use dog products on cats).
The cat question comes up constantly and deserves its own page:
Safety Permethrin and cats: the warning every owner needs → Why it's dangerous wet, why treated clothing is fine dry, and exactly how to treat gear in a home with cats.Where permethrin fits your kit
If you're building tick protection from scratch, think in layers: treat your regular outdoor wardrobe with permethrin at the start of the season, keep a skin repellent (we rate picaridin 20% highest) in your pack, and do a tick check after every outing. Permethrin is the layer that does the most work for the least ongoing effort — treat once, protected for weeks.
The full permethrin series
Everything we've published on treating clothing for ticks:
Frequently asked
Does permethrin repel ticks or kill them?
Both, but killing is the main event. A tick crossing treated fabric picks up a lethal contact dose before it reaches skin. The repellent effect is secondary — its real value is that it's deadly to ticks on contact, which is why the CDC recommends it for clothing in tick country.
Can I put permethrin on my skin?
No. It's for clothing, gear, and fabric only — on skin it breaks down fast and does little. Use picaridin or DEET on skin, and save permethrin for treating clothing. Apply outdoors, dry fully before wearing, keep wet spray away from cats.
How long does permethrin last on clothing?
A DIY spray lasts about 6 weeks or 6 washes; factory-treated garments last roughly 70 washes. Gentle, cold washing and line-drying extends it.
Is permethrin safe for kids and pets?
Treated clothing is considered safe for children once dry, and safe for dogs. Wet permethrin is toxic to cats — treat outdoors, dry completely, then it's inert. Full details here.