[17] For treatment of scabies: Adults and children older than 2 months are instructed to apply the cream to the entire body from head to the soles of the feet.

Its use is controversial because, as a broad-spectrum chemical, it kills indiscriminately; as well as the intended pests, it can harm beneficial insects, including honey bees, as well as cats and aquatic life.

A method of reducing deer tick populations by treating rodent vectors involves stuffing biodegradable cardboard tubes with permethrin-treated cotton.

[citation needed] Permethrin is used in tropical areas to prevent mosquito-borne disease such as dengue fever and malaria.

[citation needed] Permethrin is the most commonly used insecticide worldwide for the protection of wool from keratinophagous insects such as Tineola bisselliella.

[26] To better protect soldiers from the risk and annoyance of biting insects, the British[27] and US armies are treating all new uniforms with permethrin.

This differs to the most common mechanism of insecticide resistance evolution which is selection for preexisting, low-frequency alleles.

[31] Permethrin is moderately toxic if ingested, causing abdominal pain, sore throat, nausea and vomiting.

If inhaled, permethrin may cause headache, respiratory irritation, difficulty breathing, dizziness, nausea and vomiting.

[32] Permethrin has little systemic absorption, and is considered safe for topical use in adults and children over the age of two months.

[34] Permethrin does not present any notable genotoxicity or immunotoxicity in humans and farm animals, but is classified by the EPA as a likely human carcinogen when ingested, based on reproducible studies in which mice fed permethrin developed liver and lung tumors.

[37] Distribution of permethrin has been studied in rat models, with highest amounts accumulating in fat and the brain.

[citation needed] Metabolism of permethrin occurs mainly in the liver, where the molecule undergoes oxidation by the cytochrome P450 system, as well as hydrolysis, into non-toxic metabolites.

[41] In the early 1970s, it was identified that in many pyrethroids, including all natural pyrethrins and some synthetic analogs developed by that time (such as resmethrin), the furan ring, being a probable site for photo-sensitized attack by oxygen, was responsible for their instability in air and light.

Hence, a group of agricultural chemists at the Rothamsted Experimental Station led by Michael Elliott tried to substitute the 5-benzyl-3-furylmethyl alcohol with quite a few structurally similar ones.

Discovering that an ester of 3-phenoxybenzyl alcohol with a slightly modified (chlorine-substituted) analog of the chrysanthemic acid they also found earlier was both photo-stable and very toxic for insects, they filed their patent applications in 1972 and published their results in Nature in 1973.

[44] In general, the final step in the total synthesis of any of the synthetic pyrethroids is a coupling of a DV-acid ester and an alcohol.

[44] In Nordic countries and North America, a permethrin formulation for lice treatment is marketed under trade name Nix, available over the counter.

[52] Toxic exposure of permethrin can cause several symptoms, including convulsion, hyperaesthesia, hyperthermia, hypersalivation, and loss of balance and coordination.