Ciprofloxacin
"I was prescribed Cipro for five days (2 a day).  I took one the first day. That night I had terrible scary hallucinations.  I couldn't sleep (obviously when you see faces in your window, black hooded creature in your mirror, etc.). The next day I took one pill in the morning and one at night.  I was very shaky that day and pretty much out of it.  I had a hard time focusing.  That night I had more hallucinations than the night before. Scared me a lot!  Third day I only took1/2 a pill. Still had hallucinations and music playing only in my ears, no one else could hear it. It was the worst experience of my life.  I called the doctor, explained my situation, and he prescribed something else and it worked. Slept like a baby."