Cephalexin
"I was prescribed 500mg 4 times a day for 10 days to treat my folliculitis after shaving with a bad razor. The first day I felt okay, but I'm on day 4 and I already feel like crap. I feel dizzy, extremely fatigued to the point where I feel like a lifeless potato, nausea, lightheadedness, and some mild abdominal pain here and there. I pretty much don't feel like doing anything. The folliculitis seems to be slowly improving, though it flares up again when I wake up so I'm not entirely sure if this antibiotic is working. Might discontinue it if side effects get worse and try to get a different antibiotic"