Levofloxacin
"I was prescribed 500mg for 10 days for acute bronchitis, sinus infection as well as a very painful ear infection.  After the first dose, I did feel a bit better.  The second dose marked a big difference in how I was feeling overall.  I was also prescribed a very expensive inhaler of Albuterol.  (Rarely use)
The third day was when I noticed that the side effects were now more of a problem than my illness. Metallic taste in my mouth, severe dry mouth, leg cramps, NO sleep, rise in BP and HR. dizziness, and ringing in my ears, agitation.  I am on day 5 and do not want to finish the prescription but was warned, "take it completely..even after you begin to feel better."
The only positive off chart effect is my skin is glowing!"