acne
"I started taking doxycycline last year around May, because the acne on my back was getting worse and worse. 
These pills are really hard for me to take, because they make me so nauseous. It took a month or two but completely cleared up my back, and the skin on my face was flawless. 

Being dumb, I completely stopped taking them, because my skin was so clear and I was sick of the nausea so they didn't seem worth it. (My doctor recommended that I slowly phase them out, should have listened.)

Around Christmas time, my face started breaking out worse then it ever has. (Although my back was still super clear) 
I think it was stress that caused the acne, but either way it was really bad and only getting worse. So I've started taking them again."