Amoxicillin / clavulanate
"This is by far the worst antibiotic I've ever taken. Hours after my first dose I had severe stomach pain and was up all night running back and forth to the bathroom. My fitbit has also been telling me that my heart beat is faster than normal, I've been in fat burn mode while laying in bed.. I've definitely noticed insomnia as I've been up until 3-4am all week. I'm always tired as well. I'm only halfway through the pills, and there is no way I'll ever take them again as today I woke up with more severe stomach pain. My sinuses do feel better though."