Yes, I honestly thought she was going to drop down dead from it, she became very ataxic, was tremoring and unaware of what was around her
luckily it stopped pretty quickly once I rinsed her off. I only used it perhaps 4 times per year, always drew up the neat stuff with a syringe and put into premeasured out water so I knew it was diluted correctly, sponged it on so we weren't breathing it in etc.
I just spoke with the vet again and we agree it is worth doing some patch testing with her to see if she could possibly tolerate just having her legs deosected (or treated with another version of permethrin) as that is the most effective against stable flies, if only to get her over the hump and let everything calm down.