This goes back into the Hartz recalls a few years back.

Permetherins are dangerous I don't care how 'natural' they like to advertise them. Maybe 20 years ago when it was about all there was for fleas/ticks it was better than nothing. With today's safer alternatives people really shouldn't be using the Permethrin/Pyretherin products anymore, the money you think you're saving may result in at best no dent in the flea population, at worst the life of your pet. It's just not worth it.