Gabapentin
"I was prescribed Gabapentin for nerve entrapment related pain.  I'm 31, slightly overweight, but otherwise healthy according to my last round of physicals.  I also am not diabetic.  

My doctor recommended 300 mg, three times per day.  Gabapentin made me tired, forgetful, imbalanced, temperamental, emotional, dizzy, decreased my short term memory and ultimately made me sluggish in thought.  The only thing Gabapentin did not do was relieve pain.  I gave it 30 days before discontinuing.  It took two months before my thoughts and memory were no longer sluggish.  (I literally had delayed speech, slurred speech and developed a stutter.)"