Metronidazole
"I took Flagyl for bacterial vaginitis and thought I was dying.  The nausea and headaches are unbearable but because I know it works I had to keep taking it. On the fourth day I started taking it with orange juice and eating after, and WALAH! It was so much better.  No more headaches or nausea. Not sure if it was because I was halfway done with the med, or if my orange juice really worked. Hope this helps someone."