I've read a few articles about how some antibiotics can cause a worsening of neurological symptoms in people who are neurologically compromised. I found out about it when I read the info packet that came with some antibiotics I was taking once.

Quinilones (Cipro) and Nitrofurantoin (Macrobid) are two that I've read about that have a side effect of worsening nerve damage.

I still will take those antibiotics because hopefully it'll kill whatever nastiness that's latched onto me when I'm sick. I dont know if the side effects are permanent or not tho.