Metronidazole
"I absolutely HATE this medication. Being a vegetarian, I typically eat a lot of probiotics, so thankfully I didn't have the diarrhea side effect, but oh my goodness the nausea was incredibly awful. This is the third time I've had to take this, and without fail this always happens. Thankfully I've never actually thrown up, but I'd be lying if I said I haven't been keeled over the toilet crying, with my boyfriend holding frozen Brussel sprouts to my neck. Delightful."