I've been on doxy, 100 mg once a day, for almost a year and I'm pretty much clear right now. I'm also on benzaclin, which I use at night. I've had no problem with the doxy. I have noticed that when I take it on an empty stomach, it almost makes my stomach turn. I usually take it with a swig of milk and I'm fine after that! Other than the stomach aches on an empty stomach, I've had nothing but success with it!