Nitrofurantoin
"After reading all of the horrible reviews on this site I was terrified to take Macrobid. I waited two days hoping that the symptoms would clear and I wouldn't have to take this "awful poison." Everything I read talked about flu'like symptoms and high fevers..Scary stuff.  I finally gave in and took my first dose around 9:00am. By around 1:00pm I had a bit of a headache which was mostly controlled with Advil. Same side effect with the second and third dose. By day three I was side effect free and nearly symptom free too. I would take this again in heartbeat. Don't let the reviews scare you. Everyone reacts differently and you can't base what your experience will be off of the bad experience others had."