Eli5- similar to pet flea treatments, why can’t they invent a monthly drop for the back of human necks to combat lice?

Question

Eli5- similar to pet flea treatments, why can’t they invent a monthly drop for the back of human necks to combat lice?

In: 3

Answer 1

Those sort of topical treatments generally have cumulative neurological effects. In smaller animals with shorter life expectancies, the dosages do not have enough time to accumulate to the point of causing measurable neurological damage. In humans, however, this would not be the case.