What Is Permethrin

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Permethrin is an insecticide that effectively kills and repels insects, mites, and ticks. Permethrin is widely used as the active ingredient in spot-on, powders, sprays, shampoos, emulsions, and solutions to combat lice, fleas, mites, and ticks. Permethrin is also used to treat outdoor clothing, work clothing, as well as tents and mosquito nets so that these become a more effective barrier to keep mosquitoes and ticks away.

What is Permethrin?

Permethrin is a generic name of a synthetic chemical. Permethrin is an insecticide and acaricide, it belongs to the pyrethroids, a group of synthetic insecticides, based on the naturally occurring insecticide in Chrisantenum flowers (Tanacetum cinerariifolium).

Pure permethrin is present as a yellow to slightly orange-brown, lipophilic, viscous liquid or as a dried hard substance that is almost insoluble in water.

What insects does permethrin kill?

Permethrin is poisonous to insects and kills all insects that come in contact with a high enough dose.

If an insect is only exposed to a low dose while it crawls on a surface treated with Permethrin, then the substance has a so-called “hot feet effect“. The touch is uncomfortable for insects and they just fall off the treated surface. At such a low dose exposure, many of the affected insects can recover and survive.

It has been used for a long time in the following areas of application:

  • Bug spray
  • Moth traps
  • Rid homes of Bedbugs
  • In shampoo against head lice
  • In creams against scabies
  • Treatment to rid pets of fleas, ticks, and other ectoparasites
  • Treat outdoor gear and clothing to repel bugs

How does Permethrin Work

The insecticide permethrin has an incapacitating effect on insects and mites, paralyzing and killing them. In order to trigger the effect, the parasites only have to come into contact with the substance, absorption takes place via the body surface. It acts as a neurotoxin, as such it spreads rapidly throughout the insect’s body, affecting the muscles and nervous system of the parasite.

Inside the bug, it causes sensory overexcitability through the uncontrolled release of neurotransmitters, coordination disorders, and exhaustion which results in cramps, and paralysis. The insect is unable to move within a few minutes, one speaks of a “knock-down” effect. This ultimately leads to the death of the insect.

Acute toxicity to humans and most mammals is low when used as recommended. Absorption is low, permethrin is oxidatively broken down in the liver and quickly excreted.

Permethrin is highly toxic to aquatic life such as fish, amphibians, and reptiles. It must not get into waterways.

Products containing permethrin must never be used in cats. It is toxic to cats as they lack the enzyme necessary to break it down.

Mode of application of permethrin

There are different forms of application for permethrin. For pets, the most common are Spot on preparations or collars. Other formulations are lotions, cream, and pump sprays depending on their use.

Spot-on for dogs:

There are different spot-on medications of permethrin is available for dogs. A spot-on preparation is convenient to use and easy to apply. Drop by drop from a bottle or from a pre-dosed ampoule, the active ingredient is applied to the dog in the neck or between the shoulder blades.

The active ingredient distributes throughout the whole fur via the dogs’ fat glands (sebaceous glands). Ticks and fleas die within 48 hours after contact with skin or fur, hopefully, before they suck blood. A single treatment usually lasts up four to eight weeks depending on the dose. Often products are a combination of permethrin and picaridin or other repellents.

Anti-tick collar:

Anti-parasite collars are convenient to protect pets against ticks, fleas, and mites. Its mode of application is very simple and easy. Simply put the collar around the neck of the animal. Compared to spot-on preparations, which usually have to be dripped onto the skin of the pet every few weeks, the collars keep their protective effect for weeks and months. After application, the active ingredients are continuously distributed via the natural fat film to the skin and coat.

Don’t Use Permethrin On Cats, Its Toxic

In contrast to dogs, spot-on products and collars containing permethrin must never be used on cats. The cat’s organism lacks the enzymes necessary to break down permethrin, so it is highly toxic for cats. Typical symptoms of poisoning by permethrin in cats are central nervous symptoms such as tremors, excessive salivation, cramps, shortness of breath, but also vomiting, diarrhea, or fever. If the cat has had contact with permethrin-containing solutions, you should bathe them immediately with mild detergents and then consult a veterinarian.

Anti-tick sprays for clothing

There are also permethrin sprays available to treat clothing and create a protective shield that repels or kills parasites that get in contact with the garment. You may buy clothing that is already factory-treated or buy the spray and treat the fabrics yourself. The application is very simple, make sure you follow instructions.

Fabrics treated with permethrin cause a “hot foot effect” in ticks or if exposure is high cause the tick to die, either way, they fall off before they find a suitable bite site. and as a result, they simply fall off.

These sprays also work for treating shoes, boots, waders, backpacks, tents, camp furniture, hammocks, mosquito netting, luggage, and bedsheets.

How to treat Clothing with Permethrin

  • Read instructions, treat clothing with permethrin exactly as instructed
  • Use protective gloves
  • Apply outside in the open air
  • Place the clothes on a flat surface
  • Evenly spray the clothing according to the instructions
  • Allow the clothing to dry completely before use
  • Wash treated clothing separately from other items of clothing
  • After multiple washes, treat clothing as needed.

Permethrin is only for surface treatment of fabrics and equipment. Do not apply to the human skin.

Rare side effects and dangers

As with everything: where there is a desired effect there can also be an undesired effect. Some rare side effects that are associated with permethrin use may include:

  • Mild burning and stinging sensation
  • Tingling at the site of application
  • Numbness of skin
  • Itching
  • Redness of skin
  • Skin rashes
  • Swelling of skin

People in today’s world seem to become more and more allergic to all sorts of stuff, from peanuts to strawberries, to prawns, everything is possible. So it’s no wonder that mild to severe allergic reactions to permethrin can also occur.

If you are allergic to it, you must avoid its use. If you notice any symptoms of an allergic reaction seek immediate medical attention. The symptoms of an allergic reaction to permethrin include but are not limited to:

  • Rash
  • Itching
  • Swelling of the face, tongue, and throat
  • Severe dizziness
  • Trouble breathing


  • Highly effective
  • Repels and kills parasites such as ticks, mites, fleas, and lice, mosquitos, etc.
  • Provides long-lasting protection
  • Suitable for treatment of acute infestations
  • Different formulations and modes of application are available


  • Toxic to all insects, kill beneficial organisms too, such as bees
  • May cause allergic reactions
  • Very toxic to cats
  • Highly toxic to aquatic organisms

Conclusion: Is permethrin safe?

Protection against parasites is critical to prevent diseases. Tick-borne and mosquito-borne diseases are some of the greatest plaques and kill millions of people every year. Animals and pets are just as affected.

Permethrin is used as a contact and feeding poison against ticks and fleas in dogs and has proven itself millions of times over in the last few decades as a well-tolerated and reliably preparation that fleas and ticks at a distance or ensures that they are quickly killed.

Permethrin is ideal also for treating mosquito nets and clothing. Harmful effects on humans and undesirable side effects have so far hardly been known and can be neglected compared to the benefit of using insect repellents.

For additional protection against ticks and blood-sucking insects that can transmit diseases, personal insect repellents are recommended.

Source and more to read:

National Pesticide Information Center

Health Effects of Permethrin-Impregnated Army Battle-Dress Uniforms