Metronidazole
"The taste was bad, but not awful. I had the dosage of a one time four 500mg tablets. The side effects were as bad as everyone says. I hadn't read anything about the drug before taking it. I took it with a meal and still felt nauseous all night. My side effects were vomiting, chills, major headache, dizziness, tingling in hands and feet, dryness of mouth, fatigue, and trouble sleeping. I wish I would have known about the side effects before taking the medicine, because I was afraid to be home alone.  They only lasted the night, after that I was back to normal."