Doxycycline
"My acne cleared up over a couple months, but after I finished the course, my digestive system was destroyed. For four years I struggled to figure out what was wrong with me, I was plagued by brain fog, poor memory, and low energy levels after eating certain foods. Turns out, the doxycycline decreased my gut motility, killed off a large percentage of my good bacteria, and ultimately I developed something called SIBO (small intestine bacterial overgrowth). I'm currently being treated for SIBO, but I will likely never be able to properly digest gluten or dairy again and I'm only 20 years old. Trust me when I say that taking this for acne is not worth it under any circumstance. Diet is a much better option."