Permethrin is a common synthetic chemical, widely used as an insecticide and acaricide and as an insect repellent. It belongs to the family of synthetic chemicals called pyrethroids and functions as a neurotoxin, affecting neuron membranes by prolonging sodium channel activation. It is not known to harm most mammals or birds. It generally has a low mammalian toxicity and is poorly absorbed by skin.
In agriculture, permethrin is mainly used on cotton, wheat, maize,
and alfalfa crops, and is also used to kill parasites on chickens
and other poultry. It is also extensively used in Europe as a timber
treatment against wood boring beetle (woodworm). Its use is controversial
since, as a broad-spectrum chemical, it kills indiscriminately;
as well as the intended pests, it can harm beneficial insects including
honey bees, aquatic life, and small mammals such as mice. Permethrin
is toxic to cats and many cats die each year after being given flea
treatments intended for dogs, or by contact with dogs who have recently
been treated with permethrin. However, permethrin can be used in
a targeted manner as well. This is the basis for a method of reducing
populations of the deer tick Ixodes scapularis (I. dammini). Biodegradable
cardboard tubes stuffed with permethrin-treated cotton, are sold
under the brand name Damminix, Mice collect the cotton for lining
their nests, and the pesticide on the cotton kills any immature
ticks that are feeding on the mice. Permethrin is also used in healthcare,
to eradicate parasites such as head lice and mites responsible for
scabies, and in industrial and domestic settings to control pests
such as ants and termites. Permethrin kills ticks on contact with
treated clothing. According to the Connecticut Department of Public
Health, it "has low mammalian toxicity, is poorly absorbed through
the skin and is rapidly inactivated by the body. Skin reactions
have been uncommon."Permethrin is used in tropical areas to prevent
mosquito-borne disease such as dengue fever and malaria. Mosquito
nets used to cover beds may be treated with a solution of permethrin.
This increases the effectiveness of the bed net by killing parasitic
insects before they are able to find gaps or holes in the net. Malaria
kills 1-3 million people per year, and permethrin is believed to
have very low if any toxicity in humans. Military personnel training
in malaria-endemic areas may be instructed to treat their uniforms
with permethrin as well. An application should last several washes.Adults
and children: Thoroughly massage ELIMITE® into the skin from the
head to the soles of the feet. Scabies rarely infests the scalp
of adults, although the hairline, neck, temple, and forehead may
be infested in infants and geriatric patients. Usually 30 grams
is sufficient for an average adult. The cream should be removed
by washing (shower or bath) after 8 to 14 hours.
In clinical trials, generally mild and transient burning and stinging followed application with ELIMITE® in 10% of patients and was associated with the severity of infestation. Pruritus was reported in 7% of patients at various times post-application. Erythema, numbness, tingling, and rash were reported in 1 to 2% or less of patients