bladder infection
"I have been on macrobid twice for bladder infections.  It cleared them up, but the side effects knocked me off my feet for days.  Fever of 101 - 102 and flu-like achiness and wicked headaches or the entire time I was on the medication.  The first time I took it the doctor said I must have had the flu too.  The second time I called him after three days and had him switch me to another antibiotic."