Etofenprox is an antiparasitic active ingredient used in veterinary medicine mainly in pets against external parasites (lice, mites, fleas, fliesticks, etc.). It is also used against agricultural pests. It belongs to the chemical class of the synthetic pyrethroids-ethers.

Common name: ETOFENPROX

Type: pesticide
Chemical class: synthetic pyrethroid-like (so-called non-ester pyrethroid)





Type of action: Broad spectrum contact, non systemic ectoparasiticide: insecticide, acaricide, tickicide, louisicide
Main veterinary parasites controlled: flies, ticks, mites, lice, fleas, mosquitoes, etc.

Efficacy against a specific parasite depends on the delivery form and on the dose administered. National regulatory authorities determine whether a product is approved for a given indication, i.e. use on a particular host at a specific dose and against a specific parasite. Check the labels of the products available in your country.

Click here for general information on features and characteristics of PARASITICIDES.


Oral LD50, rat, acute*:  >2000 mg/kg
Dermal LD50, rat, acute*: >2000 mg/kg
* These values refer to the active ingredient. Toxicity has to be determined for each formulation as well. Formulations are usually significantly less toxic than the active ingredients.

WARNING: Most synthetic pyrethroids can be toxic for cats.

MRL (maximum residue limit) established for either beef, mutton pork or chicken meat*:

  • EU: No
  • USA: No
  • AUS: No

* This information is an indicator of the acceptance of an active ingredient by the most influential regulatory bodies for use on livestock. An MRL for meat may be established also for agricultural pesticides that are not approved for use on animals but are used on commodities fed to animals. It may be also established in the form of an IMPORT TOLERANCE for active ingredients not approved in a particular country but approved for imported animal commodities.

Withholding periods for meat, milk, eggs, etc. depend on delivery form, dose and national regulations. Check the product label in your country.

Learn more about etofenprox safety.

General safety information for antiparasitics is available in specific articles in this site (click to visit):


Never use products for livestock on dogs and cats unless they are explicitly approved for both livestock and pets. Pets may not tolerate livestock formulations.

Never use agricultural or hygiene products with this or any other active ingredient on livestock or pets, even if there are veterinary products with this same active ingredient approved for use on animals. The formulations for agricultural or hygiene use are different and may be toxic for livestock or pets.

It is obvious that veterinary products are not intended for and should never be used on humans!!!


Decade of introduction: 1980
Introduced by: MITSUI
Some original brands: TREBON, VECTRON
Patent: Expired (particular formulations may be still patent-protected)

Use in HORSES: No
Use in
DOGS: Yes, moderate

Main delivery forms:

Use in human medicine: No
Use in
public/domestic hygiene: Yes
Use in
agriculture: Yes
Generics available:



On pets: NO. However, cross-resistance with synthetic pyrethroids has been reported on mosquitoes and some crop pests. Resistance to synthetic pyrethroids is quite frequent worldwide in dog and cat fleas (Ctenocephalides spp).

Visit also the section in this site about parasite resistance to antiparasitics and more specifically to synthetic pyrethroids.


Etofenprox is a pyrethroid-like chemical. The key difference is that whereas all pyrethroids are esters, etofenprox is an ether. It is a broad-spectrum insecticide, moderately used in dogs, but not used in livestock. It is also moderately used in agriculture (mainly in rice) as well as in public and domestic hygiene for vector control.

For dogs it is often used in mixtures with insect development inhibitors. Some products contain also synergists.

Efficacy of etofenprox

Etofenprox is an ectoparasiticide, i.e. active only against external parasites such as flies, lice, mosquitoes, ticks and mites. It can be considered as a broad-spectrum generalist, i.e. quite good against almost all insects, ticks and mites, but not outstanding against a particular parasite. Residual effect depends strongly on the delivery form and the dose administered.

However, resistance to synthetic pyrethroids (e.g. cypermethrin, cyphenothrin, deltamethrinpermethrin, etc) is widespread and can be very high in dog and cat fleas (Ctenocephalides spp) and etofenprox has some cross-resistance with synthetic pyrethroids. As a consequence, products with etofenprox  (spot-on - squeeze-on - pipettes, shampoos, soaps, etc.) may not achieve the expected efficacy.

Pharmacokinetics of etofenprox

Topically administered etofenprox remains mostly on the hair-coat of the treated animals and is very poorly absorbed through the skin. However, treated animals can ingest etofenprox through licking or grooming. In dogs, ingested etofenprox was quickly but incompletely (~50%) absorbed to blood. Maximum blood levels were reached 1-6 hours after ingestion. Absorbed etofenprox is mostly metabolized in the liver to non-toxic metabolites that are excreted through urine. Unabsorbed etofenprox and part of its metabolites were excreted through feces.

Mechanism of action of etofenprox

Etofenprox acts on the membrane of nerve cells in the same way as synthetic pyrethroids: it blocks the closure of the ion gates of the sodium channel during re-polarization. This strongly disrupts the transmission of nervous impulses. At low concentrations insects suffer from hyperactivity. At high concentrations they are paralyzed and die.

Click here to view the list of all technical summaries of antiparasitic active ingredients in this site.