Metronidazole
"Like everyone else,  I have headaches that come and go, cramping, bloating, night sweats, disoriented and I feel a slight case of heartburn when I first swallow. The worst part, so far, is the dry mouth. The sides of my mouth feel like cardboard and all that I want to do is drink water but it’s making me urinate a lot more. 
There is one side effect that I’ve had that I haven’t seen anyone else mention yet.  I have been on my period since I’ve started the pills, and this has been the strangest period that I’ve ever had. This period is heavier and is a brighter red than normal. Two hours after my initial first pill, I started gushing blood. I can’t wait until I’m done with this."