Permethrin

Permethrin
	Two-dimensional chemical structure of permethrin
	Three-dimensional chemical structure of permethrin
Clinical data
Trade names	Nix, Rid, Elimite, others
AHFS/Drugs.com	Monograph
MedlinePlus	a698037
License data	US DailyMed: Permethrin;
Routes of; administration	Topical
ATC code	P03AC04 (WHO) QP53AC04 (WHO);
Legal status
Legal status	CA: OTC; UK: OTC (1%), Rx (5%); US: OTC (1% pediculicide), Rx (5% scabicide);
Pharmacokinetic data
Metabolism	Liver
Identifiers
	IUPAC name (±)-3-Phenoxybenzyl 3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropanecarboxylate;
CAS Number	52645-53-1 ;
PubChem CID	40326;
DrugBank	DB04930;
ChemSpider	36845;
UNII	509F88P9SZ;
KEGG	C14388;
ChEBI	CHEBI:34911;
ChEMBL	ChEMBL1525;
CompTox Dashboard (EPA)	DTXSID8022292 ;
ECHA InfoCard	100.052.771
Chemical and physical data
Formula	C21H20Cl2O3
Molar mass	391.29 g·mol−1
3D model (JSmol)	Interactive image;
Density	1.19 g/cm3, solid g/cm3
Melting point	34 °C (93 °F)
Boiling point	200 °C (392 °F)
Solubility in water	5.5 × 10−3 ppm, 0.2 mg/mL (25°C)
	SMILES Cl/C(Cl)=C/C3C(C(=O)OCc2cccc(Oc1ccccc1)c2)C3(C)C;
	InChI InChI=1S/C21H20Cl2O3/c1-21(2)17(12-18(22)23)19(21)20(24)25-13-14-7-6-10-16(11-14)26-15-8-4-3-5-9-15/h3-12,17,19H,13H2,1-2H3; Key:RLLPVAHGXHCWKJ-UHFFFAOYSA-N;

Permethrin is a medication and an insecticide. As a medication, it is used to treat scabies and lice. It is applied to the skin as a cream or lotion. As an insecticide, it can be sprayed onto outer clothing or mosquito nets to kill the insects that touch them.

Side effects include rash and irritation where it is applied. Use during pregnancy appears to be safe, and it is approved for use on and around people over the age of two months in the United States. Permethrin is in the pyrethroid family of medications. It works by disrupting the function of the neurons of arthropods such as lice, mites, insects, and shrimp, making it highly toxic to these animals. It is also highly toxic to fish. It is of low toxicity to birds and mammals. However, cats are more sensitive to it than other mammals due to much slower metabolism.

Permethrin was discovered in 1972. It is on the World Health Organization's List of Essential Medicines. In 2022, it was the 351st most commonly prescribed medication in the United States, with more than 40,000 prescriptions.