I was left with small fiber neuropathy (nerve damage) in my arms and legs, and with CFS (Chronic Fatigue Syndrome) too. This means I'm in constant, unending pain (which takes a huge mental toll), that I'm tired all the time, and if I do any more than the gentlest of exercise, I fall asleep and am more tired and in even more pain for days or even weeks afterwards. It's fucking horrible.
This was about 6 years ago, and I'm pretty sure it's permanent. I haven't quite given up hope though - I have several Google Scholar alerts setup, and read several papers every week, in the hope of finding something that might reverse things even a bit.
It is actually an antibiotic (I'd somehow forgotten that - edited my original comment now!), but once that acts as a immunosuppressant, and it's less-common name is diaminodiphenyl sulfone.
After the very first pill I was feeling pins and needles in my extremities later that day. I stuck with it for a few more days, each pill feeling even more pins and needles, more intensely and in more places on my body. Once I started feeling it in my face, I called the doctor and they got me on a different antibiotic.
Then I started reading horror stories about the drug and it made sense. I also didn't exercise for a year afterwards out of fear that my achilles tendon would snap, one of the biggest warnings that was on the box and one of the things many of the online horror stories said happened to them.
The neuropathy (pins and needles) lasted for six months before it started going away, and it comes and goes periodically, years later (it's mostly gone now, thankfully). I've had other health issues since that are known possible health issues from Cipro (it's so invasive and effects so many systems of your body). One of the more annoying ones lately is the onset of Tinnitus, which Cipro is known to cause. Maybe it's just a coincidence, but I'll never know for sure since most doctors still don't treat Cipro toxicity seriously or know how to test for it.
I don't think it caused brain fog, but who's to say? I don't feel as mentally acute since then, but I'm also older.
Not really looking forward to any future health problems it may lead to, and I only ever took like 5 pills of the damn thing (it was over 7 years ago now).
I'm so pissed off I wasn't even warned about this, and that it was so casually prescribed without warning. I've taken other antibiotics before and only had to worry about my gut biome getting screwed up, so I wasn't expecting to have such a terrible reaction to the meds.