Background: Pyrethroid-induced paresthesia is frequently seen after dermal
exposure to pyrethroids. Affected individuals experience a sensation of bur
ning, tingling, itching, or numbness, most commonly in the face. This occur
s 1-2 hours after the beginning of exposure and resolves spontaneously. Mec
hanisms: Paresthesia occurs as a result of a direct effect on intracutaneou
s nerve endings at very low pyrethroid doses. It is related to potency of t
he pyrethroid with pyrethroids without an a-cyano group generally showing t
he weakest effect. Conclusion: Doses sufficient to cause paresthesia are fa
r lower than those causing central or systemic toxicity, Paresthesia is the
refore considered to be a localized nuisance effect. The best advice to aff
ected individuals is to prevent paresthesia from occurring through appropri
ate hygiene measures and personal protection.