Ethion is an antiparasitic active ingredient used in veterinary medicine in dogs and livestock against external parasites (lice, mites, fleas, fliesticks, etc.). It is also used against agricultural and household pests. It belongs to the chemical class of the organophosphates.

Common name: ETHION

Type: pesticide
Chemical class: organophosphate


Molecular structure of ETHION





Type of action: Broad spectrum contact, non systemic ectoparasiticide: insecticide, acaricide, tickicide, louisicide, larvicide
Main veterinary parasites controlled: flies, lice, fleas, mosquitoes, ticks, mites, fly maggots (cutaneous myiasis), etc

Efficacy against a specific parasite depends on the delivery form and on the dose administered. 

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


Ethion is a broad-spectrum organophosphate highly effective against many external livestock and pet parasites such as flies, ticks, mites, lice, fleas, mosquitoes, etc. but is completely ineffective against internal parasites when administered topically (i.e. on the skin).

As most organophosphates, ethion products are used for topical administration, either as concentrates (for dipping or spraying) or in ready-to-use larvicidal dressings, pour-ons and a few ear-tags for livestock. Usage in dogs is irrelevant. Ethion is often used in combination with other compounds (mainly synthetic pyrethroids). Nowadays usage has strongly declined in most regions because it has been replaced by newer, more effective and less toxic compounds.

However, resistance to all organophosphates is already very frequent worldwide, particularly in cattle ticks, houseflies, mosquitoes, fleas, etc.

The table below indicates some usual dosing recommendations for ethion issued by manufacturers or documented in the scientific literature. They may not be approved in some countries.

Dosing recommendations for ETHION
Delivery Parasites Dose (against ethion-susceptible parasites)
Dip, spray Ticksflies, mites, lice 400-650 ppm (=mg/L) in the wash, dep. on indications
Pour-on Ticksflies, mites, lice 4-20 mg/kg, dep. on indications
Delivery Parasites  Dose (against ethion-susceptible parasites)
Dip, spray Ticks, lice, mites 400 ppm (=mg/L) in the wash
Pour-on Ticks, lice, mites 15-80 mg/kg, dep. on indications
Delivery Parasites  Dose (against ethion-susceptible parasites)
Spray Lice, mites 400 ppm (=mg/L) in the wash
Delivery Parasites  Dose (against ethion-susceptible parasites)
Spray Flies, lice, ticks 400 ppm (=mg/L) in the wash

DISCLAIMER: Liability is denied for any possible damage or harm to persons, animals or any other goods that could follow the transmission or use of the information, data or recommendations in this site by any site visitor or third parties.

Dosing recommendations for antiparasitics depend on national regulations. 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 parasiteCheck the labels of the products available in your country for specific information on approved indications.


Oral LD50, rat, acute*: 208 mg/kg
Dermal LD50, rat, acute*: 915 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.

MRL (maximum residue limit) set for animal tissues (e.g. beef, mutton pork or chicken)*:

  • CODEX: No, withdrawn
  • EU: No, withdrawn
  • USA: No
  • AUS: Yes

* This information is an indicator of the acceptance of an active ingredient by the most influential regulatory bodies for use on livestock. MRL's for animal tissues may be set also for agricultural pesticides that are not approved for use on animals but are used on commodities fed to animals. A MRL may be also set 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.

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


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: 1950
Introduced by: FMC
Some original brands: TIXAFLY
Patent: Expired (particular formulations may be still patent-protected)

Use in LIVESTOCK: Yes, moderate, but declining, as all organophosphates<
Use in HORSES: No
Use in
DOGS and CATS: Yes, very scarce

Main delivery forms

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


  • In livestock: Yes, as for all organophosphates: very frequent worldwide in such species as cattle ticks (Boophilus spp), horn flies (Haematobia irritans), sheep lice (Damalinia ovis), poultry mites (Dermanyssus gallinae), houseflies (Musca domestica), mosquitoes
  • In pets: Yes, 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 ethion.


Ethion is a classical, veteran parasiticide belonging to the organophosphates. It has been used moderately on livestock, and very scarcely on pets.

On livestock it is still used in some countries in cattle, sheep and pig in concentrates for dipping and spraying, in ready-to-use pour-ons and dressings and in insecticide-impregnated ear-tags.

There are also numerous mixtures, mainly with synthetic pyrethroids (e.g. cypermethrin, permethrin).

Nevertheless, there is a clear trend to replace all organophosphates, including ethion, with less toxic compounds.

Efficacy of ethion

As most organophosphates ethion is a broad-spectrum insecticide, acaricide and larvicide. Ethion is a "generalist" pesticide, with good average efficacy against most external parasites, but not outstanding against a particular one.

Howeverresistance of important veterinary parasites to all organophosphates, including chlorpyrifos is widespread, especially in cattle ticks (Boophilus spp), horn flies (Haematobia irritans), sheep lice (Damalinia ovis), poultry mites (Dermanyssus gallinae), mosquitoes, dog and cat fleas (Ctenocephalides spp) and houseflies (Musca domestica). As a consequence, products with this active ingredient may not achieve the expected efficacy in many places. The same applies to all other organophosphates. This is also a reason for their progressive replacement with newer active active ingredients with a different mode of action.

Pharmacokinetics of ethion

Percutaneous absorption (i.e. through the skin) of topically administered ethion depends on the animal species, the administered dose, and the extension of the treated body surface. Animals treated topically can ingest ethion through licking and grooming.

Orally administered to goats, ethion was slowly absorbed into blood (half-life of 10 hours). About 65% of the administered dose was excreted in urine, 15% in feces and 1.7% in milk, mostly in the form of various metabolites. Topically administered ethion was absorbed slower to blood (half-time of aprox. 85 hours), with only about 0.05% excreted unchanged in the milk.

Mechanism of action of ethion

As all organophosphates insecticides ethion acts on the nervous system of the parasites (but also of mammals, birds, fish and many organisms!) as inhibitor of acetylcholinesterase (also known as AchE), an enzyme that hydrolyzes acetylcholine (Ach). Ach is a molecule involved in the transmission of nervous signals from nerves to muscles (so-called neuromuscular junctions) and between neurons in the brain (so-called cholinergic brain synapses).

AchE's role is to terminate the transmission of nervous signals where Ach is the neurotransmitter (there are several other neurotrasmitters). By inhibiting the activity of AchE, carbamates prevent the termination of those nervous signals, i.e. the neurons remain in constant activity and excitation, massively disturbing the normal movements of the parasites. The bottom line for the parasites is that they are paralyzed and die more or less quickly. Organophosphates bind irreversibly to AchE, in contrast with carbamates, another chemical class of parasiticides, which bind reversibly to AchE.

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