Cephalexin
"I am very sensitive to antibiotics. Bactrim makes me nauseous, gives me a rapid heart beat, and makes me feel like I have a fever. Cephalexin on the other hand, doesn't make me feel sick at all. The only thing it really does it make me EXHAUSTED for the first 1-3 hours after taking the dose, and makes me feel high during that time. Not sure if that is a good or bad thing. However, if I stand up during this 1-3  hour time frame, I do get a little dizzy and slightly nauseous, but it's nothing. Overall, good medicine."