A Complete Guide to Permethrin Insecticide

If you’ve had an insect problem, you may have used permethrin insecticide to kill the intruders.

Permethrin is a member of the pyrethroid family. It is a synthetic agent that mimics the compound pyrethrin found in chrysanthemum flowers.

Permethrin and other pyrethroids are toxic to insects that eat or touch them. Pyrethroids work by damaging insect nervous systems, preventing normal function and causing death.

Local governments use permethrin to control mosquito populations. Consumers use it to treat lice and scabies and control home and garden pests. C

ompanies market permethrin products under different brand names. For example, treatments for scabies and lice include Elimite and Nix, while insecticides are sold by Bonide, Ortho, and Raid. 

History of Permethrin

A British chemist named Michael Elliot invented permethrin in 1972.

It proved highly suitable for agriculture because it doesn’t break down in sunlight. The United States government first approved permethrin for use on cotton in 1979. Soon after, the Environmental Protection Agency (EPA) found that it was toxic to fish, so they restricted its use on cotton.

Only professionals can use restricted-use pesticides. After further testing, the government approved permethrin for use in many agricultural settings, with limits.

Farmers cannot use permethrin near water bodies and most permethrin use is restricted to professionals.

Permethrin Products

The United States boasts over 1400 registered permethrin products. In addition to agricultural and medical uses, it is an ingredient in insect repellents, indoor and outdoor pest control formulas, and pet flea and tick treatments.

Permethrin fights a broad range of insect pests, including mosquitoes, mites, termites, fleas, and ticks.

Using a permethrin repellent won’t stain or damage clothing. Permethrin-treated clothing is popular among hikers, hunters, and gardeners to reduce insect bites and prevent mosquito or tick-borne diseases.

In tropical areas, the repellent helps prevent dengue fever and malaria. Farmers and property owners use permethrin insecticides to control various insects including caterpillars, beetles, ants, and roaches. 

Permethrin is also an active ingredient in topical creams to treat lice and scabies.

Nix is an over-the-counter medication for treating lice. The prescription medication Elimite is used to treat scabies. Both require one or two treatments separated by 7-14. Occasionally, a third treatment is required.

The Food and Drug Administration (FDA) approves the use of permethrin cream in patients aged two months and older. Parents should not use permethrin on children under two months. Sulfur, however, is safe for treating infants.

Drawbacks of Permethrin

Permethrin has low toxicity to humans and most mammals at levels used to control pests. However, it does pose a threat to cats and aquatic animals, including fish.

Even a small drop of permethrin can kill pet fish. Be sure to cover aquariums and fish bowls with plastic wrap when treating your home. When treating your yard with permethrin spray, cover fish ponds with a tarp.

Cats have trouble breaking down permethrin. The danger is most pronounced when they are exposed to doses used for flea and tick treatment in dogs.

In a study, approximately 40% of cats treated with dog doses died and the remainder were hospitalized. Even cats that spend time close to treated dogs can develop adverse reactions, including seizures.

Researchers have also studied the effects of permethrin exposure on other animals. They fed permethrin to dogs and mice for two years. The subjects’ liver weights increased and the dogs were more likely to experience tremors. Rabbits experienced irritation from 3 months of permethrin application to their skin.

What about us?

While humans should never consume permethrin, it’s unlikely to be lethal.

Inhalation and consumption can cause difficulty breathing, nausea, vomiting, and diarrhea. If permethrin gets on your skin, it may cause tingling, irritation, and a burning sensation.

A common question is: does permethrin cause cancer? There is no evidence of a link between permethrin and cancer. 

Permethrin Insecticide Around the World

After its invention, other countries adopted permethrin due to its low toxicity and success in agriculture. For example, farmers in countries such as Mexico, Brazil, and India use it.

While permethrin is legal for medical and veterinary use in Europe, the European Union does not permit its use in agriculture.

The United Kingdom recently allowed permethrin use in wood preservation. Both the US and British armies use permethrin repellent to protect soldiers from bites and insect-borne disease.

Since its development in 1972, permethrin has proved itself an effective insecticide with minimal risk to humans. However, it’s crucial that you follow the directions and do not misuse it.

Properly and safely applied, permethrin can be useful in a variety of situations against a wide range of pests.



I read that permethrin residue has been found on spinach in the US. Does cooking destroy permethrin?

    Kristiana Kripena

    If you’re referring to EWG’s Dirty Dozen foods, then while it’s true, the pesticide residue on spinach and other foods for that matter is so small that one could consume several hundreds of servings per day without any negative effects on their health. But if you want to limit your exposure to the pesticide traces you can wash the produce in cold water or baking soda water. And blanching or boiling the produce should also reduce the pesticide residue levels by at least 50% if not more.

Phil Russell

You don’t mention SFR permethrin is it different ?


    Permethrin is an ingredient while Permethrin SFR is a product that has permethrin as an active ingredient.


So…Does this mean that if a bird/lizard eats an insect that died from the permethrin, it will be fine?


    Due to its low toxicity to birds, it’s relatively safe to them. However, it could get harmful if inhaled by birds, so, as long as you can avoid that part, you should be good to go! As for lizards, we’re not sure.


I have permethrin II
I have termites around my firewood . Can I use this to kill them if so what mixture


    It might kill some it comes in contact with, though, the product isn’t labeled for termites. For advice, take a look at our article on getting rid of termites.

Ty Jamison

Can insects build an immunity to permethrin?


    Yes, insects can build up immunity to insecticides.

Cody Ashton

Will this kill black/ orange striped grasshoppers?


    Yes, insecticides with permethrin as the active ingredient, should kill lubber grasshoppers.

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