Is Permethrin Safe for Humans?

Yes, permethrin is considered safe for topical use in humans.

As a medication, permethrin is used to treat lice and scabies either as a cream or lotion. Just like any other medicine, it has certain side effects like irritation or rash on the area applied. It is approved for use by anyone above the age of 2 months.

It is one of the World Health Organization’s essential medicines. Adults and children are advised to apply the cream to their entire body and wash it off after 8 to 14 hours. When treating head lice, rub it on the neck and scalp and shampoo it after 10 minutes. Ensure the permethrin does not get in contact with the eyes.

Side effects
Excessive permethrin can cause headache, muscle weakness, nausea, shortness of breath, excessive salivation, and seizures. Permethrin has been tested on pregnant animals and has not shown any negative effects on fertility. It however has not been tested on humans either during pregnancy or lactation. Mothers are advised to temporarily stop breastfeeding during treatment.
In case of an overdose, traces of permethrin can be found in the urinary metabolites, blood plasma, or serum.

Absorption
Permethrin is minimally absorbed in the first 48 hours, after which the absorption rates see an uptick.

Metabolism
It occurs majorly in the liver; the molecule goes through oxidation and hydrolysis into metabolites and finally gets eliminated via urinary excretion.